Electrical Stimulation of PC 6 to Control Chemotherapy-Induced Nausea and Vomiting in Patients with Cancer: A Systematic Review and Meta-Analysis

Abstract

Objective: A complementary treatment for managing chemotherapy-induced nausea and vomiting (CINV) with promising results is electrostimulation of Pericardium 6 (PC 6; Neiguan). This review was conducted to evaluate the effects of electrostimulation therapy at PC 6 to control CINV in patients with cancer. The review was registered on PROSPERO (CRD42018087753).

Methods: This systematic review and meta-analysis of clinical trials was accomplished according to the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Studies written in English, Portuguese, or Spanish that met the eligibility criteria organized according to the PICO [Patient, Problem or Population; Intervention; Comparison, Control, or comparator; Outcome(s)] anagram were included. Descriptors used to search the databases were identified and selected according to the Medical Subject Headings of the National Library of Medicine. The primary outcomes evaluated were the frequency and severity of nausea, vomiting, and general emesis after the experimental protocol. The secondary outcomes evaluated were the numbers of antiemetic pills taken and the patients' quality of life.

Results: Fourteen articles were included. There was a reduction in the mean number of episodes of acute nausea (mean difference [MD] = −2.08; 95% confidence interval [95%CI] = −2.76, −1.39) and acute vomiting (MD = −0.91; 95% CI = −1.39, −0.42) or delayed (MD = −0.85; 95%CI = −1.47, −0.23) in patients given the treatment. The other analyses of nausea, vomiting and emesis showed no differences.

Conclusions: Electrostimulation at PC6 has an effect on controlling general emesis, and acute nausea and vomiting in different phases of recovery from chemotherapy in patients with cancer.

Introduction

Chemotherapy-induced nausea and vomiting (CINV) are adverse effects of this type of treatment in patients with cancer.¹ Quality of life (QoL) can be greatly impaired in patients with CINV, because uncontrolled emesis can cause severe complications such as malnutrition, anorexia, and dehydration. In addition, CINV can lead to poor adherence to, or discontinuation of, chemotherapy.^1–3

For management of CINV, the “gold standard” treatment is antiemetic drugs, such as type-3 serotonin (5-HT3) receptor antagonists, corticosteroids, neurokinin 1 (NK1) receptor antagonists, and metoclopramide.^4,5 However, these drugs do not benefit all patients and can lead to side-effects such as headaches and constipation. Controlling CINV is less effective in late emesis (after 24 hours of chemotherapy), a stage at which few antiemetic drugs have effects.^5,6 Thus, nonpharmacologic therapies are necessary for controlling CINV.⁷

A complementary treatment for managing CINV with promising results is electrical stimulation in the distal left forearm, which promotes the stimulation of the Pericardium 6 (P 6 or PC 6) acupoint.^8–10 The PC 6 acupoint, also called the Neiguan, is located at the median nerve between the tendons of the long palmar flexor and carpal radial flexor muscles, ∼2–3 cm from the wrist.¹¹ This point is used to prevent and reduce nausea, vomiting, insomnia, chest pain, tenosynovitis, and neuroses, among other symptoms.¹²

Electrostimulation at this acupoint has been performed using transcutaneous electrical nerve stimulation (TENS), transcutaneous electrical acupoint stimulation (TEAS), electroacupuncture (EA), Reliefband,^® and Sea-Band.^® Many studies have focused on their use to stimulate the PC 6 acupoint to control CINV,^8,10,11 especially because these are commonly used and low-cost techniques used in clinical practice. However, studies have reported conflicting results regarding the applicability of these approaches. Therefore, this review was conducted assess the effects of electrostimulation therapy at the PC 6 acupoint in controlling CINV in patients with cancer.

Methods

Type of Review

This was a systematic review and meta-analysis of clinical trials performed according to the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement.¹³

Study Registration

This study was registered at the International Prospective Register of Systematic Reviews on July 30, 2018 (registration number: CRD42018087753).

Eligibility Criteria

Studies published in international journals and written in the English, Portuguese, or Spanish languages that met the eligibility criteria organized according to the PICOS [Population, Intervention, Comparison, Outcome, and Type of Study] anagram were included in this review.¹⁴

Population in the Studies

Studies of patients with cancer and presenting with CINV were included in this review and meta-analysis.

Intervention

We analyzed studies using electrostimulation of the PC 6 acupoint as a contributor to reducing or controlling emesis. Electrostimulations of the following types were considered: TENS, a Reliefband electrostimulation device or miniaturized TENS bracelet, TEAS, and EA.

Comparison

The selected clinical trials were required to have an experimental group that followed the cited recommendations. This experimental group had to be compared with a control group (standard treatment or placebo). Studies that met these criteria were included in this review.

Primary Outcomes

The primary outcomes evaluated were the frequency and severity of nausea, vomiting, and general emesis after the experimental protocol. Acute episodes (occurring within 24 hours of chemotherapy or the first day) and delayed episodes (occurring ≅ to 5 days after chemotherapy) of vomiting were considered.

Secondary Outcomes

The secondary outcomes evaluated were the numbers of antiemetic pills taken and the patients' QoL.

Research Strategy

Initially, the descriptors used for searching the databases were identified and selected according to the Medical Subject Headings of the National Library of Medicine. Moreover, three descriptors not found in the database were added in the analysis (Fig. 1). The search strategies used in the selected databases are described in Appendix A1. Two independent investigators conducted a systematic review of the published peer-reviewed research articles by searching the following databases: PubMed, BIREME, Scielo, Embase, Web of Science, Scopus and the Cochrane Library and PEDro. The search was performed to identify studies published up and including to June 2020. One article that were not found in this search was added later.

FIG. 1.

Descriptors used for search strategy for the databases.

Selection of Studies

The investigators selected the articles on the basis of their titles and abstracts, excluding studies that were not related to the theme of this research (off-topic records) and that did not meet the inclusion criteria. Thereafter, the selected articles were read in full for final evaluation. During the selection, disagreements among the researchers were resolved through discussion of the points until consensus was reached. This meta-analysis included studies that adhered to the PICOS criteria. The selection of studies is presented in Figure 2.

FIG. 2.

Flow chart showing selection of studies for the meta-analysis. N = number of articles included in the systematic review.

Study Quality Assessment

The quality of the methodology used in the selected articles was analyzed using the PEDro scale.^* The PEDro scale was adopted owing to its indication in physical therapy trials.¹⁵ The scores of the studies that had previous evaluations in the database were maintained. The other studies were evaluated by 2 independent reviewers.

Selected Information

For analyzing the selected studies, the following information was extracted: population, intervention group, comparison group, outcome, type of study, and antiemetic medication.

Statistical Analysis

Descriptive results were presented regarding each study population, diagnosis, and main treatments. The size of the intervention effect was calculated for each study included in this review by using the mean difference (MD) or standardized MD, or the odds ratio (OR) with a 95% confidence interval (95% CI). When there was insufficient information to perform effect-size calculations, this information was requested from the original study authors via e-mail. In studies that had more than 1 experimental group besides the electrostimulation group, effect-size calculation was performed for all the groups combined or for each group separately, such as the control or placebo group. The results obtained in the experimental groups that did not use electrostimulation, or from those with limited data, were retained in the systematic review, but not included in the meta-analysis. When there was low heterogeneity in the data, a meta-analysis of fixed effects was performed to estimate the effect of the treatment on the patients. If there was high heterogeneity, a model for random effects was used. The absence of publication bias was analyzed using a funnel plot. The probability of a Type I error for the statistical tests was evaluated for P < 0.05. All data analyses were conducted using Review Manager (version 5.3; The Cochrane Collaboration, London, United Kingdom).

Results

Study Selection

The search using the keywords in the databases yielded 715 articles. After reading the titles and abstracts, 695 articles were excluded. Subsequently, the remaining 20 articles were read in full and 6 additional articles were excluded (Fig. 2). Finally, 13 articles were included in this meta-analysis, as shown in Table 1.

Table 1.

Characteristics of the Included Studies

1st author, year & reference	Population	Intervention group	Comparison group	Outcome	Type of study	Antiemetics used	Score on the PEDro scale
Dundee, 1987a	N = 10 Testis cancer	EA applied at PC6 + antiemetic drugs	EA applied at a false point near the right elbow + antiemetic drugs	Significant difference observed in the application of EA at PC 6 (P < 0.001), compared to the application at the false point; no side-effects	Randomized study	Metoclopramide	3
Dundee, 1989b	N = 130 Undefined cancer distributed in the groups: Pilot study: n = 15 Crossover study: n = 10) Main study: n = 105	Pilot & main studies: EA at PC 6 applied in ambulatory patients (frequency: 10 Hz) Crossover study: EA at PC 6 applied to inpatients	Pilot & main studies: EA at PC 6 applied to inpatients (frequency: 10 Hz) Crossover study: EA applied at a false point	∼ 97% of patients had considerable reduction of CINV episodes without side-effects; crossover study showed beneficial effects limited to PC 6.	Multifaceted study	Metoclopramide & prednisolone	4
Dundee, 1991c	N > 100 Undefined cancer	First study: TCES at PC 6 applied to patients hospitalized on cisplatin treatment Second study: IG1–TCES at PC 6 applied with small electrodes; IG2–TCES at PC 6 applied with large electrodes Third study: TCES at PC 6 + acupressure Fourth study: TCES at P C6 Fifth study: TCES at PC6 applied with large electrodes Sixth study: TCES at PC 6 using small electrodes applied in outpatients & hospitalized patients	First study: No CG Second study: Invasive acupuncture at PC6 Third study: Invasive acupuncture at PC6 + acupressure at PC 6 Fourth study: Acupressure at PC 6 Fifth study: CG1, invasive acupuncture at PC 6; CG2, acupressure at PC6 Sixth study: Invasive acupuncture in outpatients & hospitalized patients	Benefits were observed in 77% of patients receiving TCES, although invasive acupuncture produced better results; ∼ 88% of patients benefited from TCES; invasive acupuncture was beneficial in 96% of patients	Multifaceted study	Metoclopramide, thiethylperazine, prochlorperazine & cyclizine	3
McMillan, 1991d	N = 16 Undefined cancer Hospitalized patients	Antiemetic drugs + TENS at PC 6 (frequency: 10–15 Hz)	Antiemetic drugs (8 mg, 3 × /day during 5 days)	Combination therapy indicated better effects; 4 patients had no improvement in CINV.	Randomized crossover study	Ondansetron	3
Shen, 2000e	N = 104 Breast cancer	37 patients received EA at PC 6 and ST 36 (frequency: 2–10 Hz; pulse width: 0.5–0.7 ms, with continuous current during 20 min) + antiemetic drugs	CG1: 33 patients received false acupuncture (needles inserted superficially without manipulation) at LU 7 and GB 34 (without electric current) + antiemetic drugs CG2: 34 patients received antiemetic drugs	IG had a lower number of CINV episodes than the 2 CGs did, but without significant differences between the groups.	3-armed, parallel-group, RCT	Prochlorperazine, lorazepam & diphenhydramine hydrochloride	8
Tan, 200118	N = 25 Cancers: Testis: n = 14 Bladder: n = 11	TENS applied at PC 6 + antiemetic drugs	CG1: TENS (Reliefband®) applied at PC 6 CG2: Antiemetic drugs	Combination therapy produced better effects	Blinded, randomized prospective study	Ondansetron	6
Roscoe, 200221	N = 27 Females = 25; Males = 2 Cancers: Breast: 81% Colon or rectal: 11% Ovarian:4% Lung: 4%	TENS (Reliefband) applied at PC 6 (parameters adjusted by patients) + antiemetic drugs	CG1: TENS (Reliefband) applied at a false point CG2: Antiemetic drugs	No significant differences were observed between the groups.	Randomized clinical trial	Doxorubicin (81%); carboplatin (4%); cisplatin (4%); fluorouracil with leucovorin (11%); 5-HT3 receptor antagonists (96%)	2
Roscoe, 200322	N = 739 Cancers: Breast (95%); Hematologic neoplasms: 10% Others: 5%	IG1: TENS (Reliefband) applied at PC 6 (intensity adjusted by patients between 10 mA and 35 mA) + antiemetic drugs IG2: Sea-Band® applied during 5 continuous days (intensity adjusted by patients) + antiemetic drugs	Antiemetic drugs only	No significant differences were observed between the groups	Randomized clinical trial	All patients received standard clinical antiemetic prophylaxis, which included a 5-HT3 receptor antagonist antiemetic on the day of treatment; dexamethasone or another corticosteroid was allowed	3
Treish, 2003f	N = 44 Cancers: Breast: (n = 4) Head & neck: n = 7 Leukemia: n = 8 Lung: n = 3 Non-Hodgkin's lymphoma: n = 10 Sarcoma: n = 4 Other: n = 8	TENS (Reliefband) applied at PC 6 continuous with chemotherapy + antiemetic drugs	TENS (Reliefband) applied at a false point + antiemetic drugs	CINV episodes after treatment were reduced by 50% in the IG	Randomized, prospective, double-blinded, placebo-controlled trial	Ondansetron & dexamethasone (for acute CINV); dexamethasone + prochlorperazine or ondansetron (for delayed CINV)	7
Roscoe, 2005g	N = 96 Breast cancer	TENS (Reliefband) applied at PC 6 with intensity adjusted by patients between 10 mA & 30 mA + antiemetic drugs	CG1: TENS (Reliefband) applied at a false point + antiemetic drugs CG2: Antiemetic drugs	No significant differences were noted between the groups	RCT	All patients received standard clinical antiemetic prophylaxis, which included a 5-HT3 receptor antagonist antiemetic on the day of treatment; dexamethasone or another corticosteroid was allowed.	6
Rivaz, 2007h	N = 32 Outpatients with cancer	PC 6 was stimulated by TENS (10–15 HZ for 10 min) when the antiemetic agent was administered & continued during awakening every 2 hours for 72 hours after chemotherapy	Placebo group was treated similarly but with an off-mode stimulator	No statistically significant difference in severity of nausea was observed between the 2 groups in the first 24 hours of chemotherapy but the intensity of nausea in the TENS group was significantly lower than patients in the placebo group during 48 and 72 hours of chemotherapy; mean frequency of vomiting during the first, second, and third 24 hrs was significantly lower in the control group	Single blinded clinical trial	Granistron & dexamethasone	10
Beith, 2012i	N = 32 Breast cancer	EA applied at PC 6, LI 4, and ST 36, 2 hours before chemotherapy + antiemetic drugs	EA applied at a false point + antiemetic drugs	No significant differences observed between the groups	Randomized controlled pilot trial	Tropisetron, aprepitant & dexamethasone	7
Xiao, 201417	N = 120 Undefined cancer	60 patients received antiemetic drugs + EANI at PC 6.	60 patients received antiemetic drugs only	No statistically significant difference observed in rate of complete control of nausea & vomiting; however, there was a statistically significant difference in the response rate of nausea & vomiting	Randomized clinical trial	Palonosetron hydrochloride	6
Xie, 201716	N = 142 Primary or metastatic liver cancer	72 patients received antiemetic drugs + TEAS applied at PC 6, ST 36, & LI 4 (frequency: 4 Hz, with intensity adjusted every 10 min for 30 min ranging from 7 to 15 mA), twice daily for 6 consecutive days.	70 patients received antiemetic drugs + TEAS applied at PC 6, ST 36, and LI 4 (frequency: 4 Hz; intensity: 0 mA, during 30 min), 2 × /day for 6 consecutive days	No significant differences noted between the groups	Single-blinded, randomized, controlled clinical trial	Palonosetron hydrochloride	7

^aDundee JW, Ghaly RG, Fitzpatrick KT, Lynch GA, Abram WP. Acupuncture to prevent cisplatin-associated vomiting. Lancet. 1987;1(8541):1083.

^bDundee JW, Ghaly RG, Fitzpatrick KT, Abram WP, Lynche GA. Acupuncture prophylaxis of cancer chemotherapy-induced sickness. J R Soc Med. 1989;82:268–271.

^cDundee JW, Yang J, McMillan C. Non-invasive stimulation of the P6 (Neiguan) antiemetic acupuncture point in cancer chemotherapy. J R Soc Med. 1991;84(4):210–212.

^dMcMillan C, Dundee JW, Abram WP. Enhancement of the antiemetic action of ondansetron by transcutaneous electrical stimulation of the P6 antiemetic point, in patients having highly emetic cytotoxic drugs. Br J Cancer. 1991;64:971–972.

^eShen J, Wenger N, Glaspy J, et al. Electroacupuncture for control of myeloablative chemotherapy-induced emesis: A randomized controlled trial. JAMA. 2000;284(21):2755–2761.

^fTreish I, Shord S, Valgus J, et al. Randomized double-blind study of the Reliefband as an adjunct to standard antiemetics in patients receiving moderately-high to highly emetogenic chemotherapy. Support Care Cancer. 2003;11(8):516–521.

^gRoscoe JA, Matteson SE, Morrow GR, et al. Acustimulation wrist bands are not effective for the control of chemotherapy-induced nausea in women with breast cancer. J Pain Symptom Manage. 2005;29(4):376–384.

^hRivaz M, Asadizaker M, Elahi N, Ramzi M. The efficacy of transcutaneous electrical nerve stimulation in control of nausea and vomiting in patients undergoing chemotherapy. Iran Red Crescent Med J. 2007;9(4):182–184.

ⁱBeith J, Oh B, Chatfield MD, Davis EL, Venkateswaran R. Electroacupuncture for nausea, vomiting, and myelosuppression in women receiving adjuvant chemotherapy for early breast cancer: A randomized controlled pilot trial. Med Acupunct. 2012;24(4):241–248.

EA, electroacupuncture; CINV, chemotherapy-induced nausea and vomiting; TCES, transcutaneous cranial electrical stimulation; IG, intervention group; CG, comparison group; TENS, transcutaneous electrical nerve stimulation; ms, millisecond(s); min, minute(s); RCT, randomized controlled trial; 5-HT3, 5-hydroxytrypamine-3; hr(s), hours; EANI, electronic antinausea instrument; TEAS, transcutaneous electrical acupoint stimulation.

Study Characteristics

The methodological quality of the studies evaluated using the PEDro scale showed an average score of 5.07 ± 1.97. The main antiemetic drugs used in the studies were metoclopramide, ondansetron, and dexamethasone (Table 1).

Primary Outcomes

Nausea

The analysis of the therapeutic effect of electrostimulation on nausea is presented in Figure 3, including the number of patients who had acute and delayed nausea, mean episodes of acute nausea, and mean severity of acute and delayed nausea (intolerable, intermediate, and without nausea). The results showed the mean number of episodes (MD = 2.08; 95% CI = −2.76, −1.39; I² = 0%) of acute nausea in patients who underwent the experimental protocol.

FIG. 3.

Forest and funnel plots of the analysis of data on nausea.

Vomiting

The analysis of the effects of electrostimulation on vomiting is presented in Figure 4, including the number of patients who had acute and delayed vomiting, mean episodes of acute and delayed vomiting, and severity of acute and delayed vomiting (intolerable, intermediate, and without vomiting). The analysis showed that mean episodes of acute and delayed vomiting were reduced in the electrostimulation group.

FIG. 4.

Forest and funnel plots of the analysis of data on vomiting.

Emesis

Figure 5 shows the analysis of the number of patients who had general emesis and the severity of acute emesis (intolerable, intermediate, and without emesis). Electrostimulation had a protective effect on the number of patients who had emesis (OR = 0.11; 95% CI = 0.03, 0.44; I² = 41%) and on the types of severity of acute emesis: intolerable (OR = 0.09; 95% CI = 0.02, 0.39; I² = 0%) and without emesis (OR = 3.59; 95% CI = 1.00, 12.93; I² = 0%).

FIG. 5.

Forest and funnel plots of the analysis of data on emesis.

Secondary outcomes

The mean numbers of ingested antiemetic pills taken and QoL did not show statistical differences (Fig. 6).

FIG. 6.

Forest and funnel plots of the analysis of data on antiemetic pills taken and quality of life.

Discussion

Nausea and vomiting are common and limiting adverse effects during chemotherapy; they both impair treatment adherence. Electrostimulation is a noninvasive technique that is considered to be safe and effective,¹⁶ especially when applied for neuromodulation. This meta-analysis analyzed if electrostimulation at the PC 6 acupoint contributes to reducing or controlling emesis in patients with cancer. Thirteen studies were included in this systematic review. The analyses showed that electrostimulation was effective for controlling general emesis, especially acute episodes.

CINV can be classified as acute or delayed on the basis of the time of onset. Acute emesis occurs within 24 hours of chemotherapy administration. Delayed emesis occurs after the first day of chemotherapy and can persist ∼5–7 days.¹⁷

Emesis can be induced by chemotherapeutic agents, which cause cellular damage by releasing 5-hydroxytrypamine-3 (5-HT3) into the intestinal mucosa, activating the visceral afferents of the vagus nerve and sympathetic nerves. The sequence includes transmission of the afferent stimulus through the vagus nerve to the brainstem. These fibers communicate with the chemoreceptor trigger zone located in the area postrema and nucleus of the solitary tract, stimulating the vomiting center in the medulla oblongata and generating the vomiting reflex¹⁸ or nausea when less sensitized. The efferent stimulus follows 3 pathways: (1) the dorsal nucleus of the vagus (opening of the gastric cardia); (2) the nucleus of the hypoglossal nerve (tongue protrusion); and (3) the reticulospinal tracts. The reticulospinal tracts can respond via the sympathetic fibers (T-5–T-12) through the celiac plexus, resulting in pylorus closure; via the phrenic nerve (C–3–C–5), which stimulates diaphragmatic contraction; and via the thoracoabdominal nerves, resulting in increased intra-abdominal pressure.^19,20

For relieving emesis, Traditional Chinese Medicine proposes the beneficial effects of stimulating the PC 6 acupoint.²¹ However, the underlying mechanism remains unclear.^11,21,22 Studies have proposed that a low-frequency electrical pulse ascends to the nervous system through the median nerve to the cerebral cortex, controlling CINV.¹⁷ However, other hypotheses can also be considered. Given that the electrical impulse initially stimulates the skin in the region of the PC 6 acupoint, other nerves. such as the medial (C-8–T-1) and lateral antebrachial cutaneous nerves (C-5–C-6), could also be stimulated directly. Considering these spinal levels,²⁰ Electrostimulation of the lateral antebrachial cutaneous nerve could result in neuromodulation, via the corresponding afferent stimulus in the medullary level of C-5 that corresponds to the action of the phrenic nerve (C-3–C-5), which contributes to reducing emesis.

In addition, given that this type of stimulus (conscious proprioception and vibration) ascends and sensitizes the second neuron in the gracile and cuneate nuclei of the bulb,²³ the current authors hypothesized that this pathway might contribute to neuromodulation of the vagus nerve. The physiologic mechanism proposed by Xiao et al. was also considered.¹⁷ The electrical pulse can adjust the transfer signals between the stomach and the vagus nerve, preventing the transmission of signals that induce vomiting, reducing the release of 5-HT3, and resulting in the downregulation of 5-HT3 receptors and inhibition of CINV.¹⁷

In this meta-analysis, a beneficial effect was found when general emesis was analyzed. However, the specific analysis identified that the applied experimental protocols induced effects only in the mean episodes of acute nausea and delayed or acute vomiting. Therefore, the current authors have some proposals that justify these results. Initially, the effects of electrostimulation might decline over time because of habituation was considered, thereby necessitating constant changes in stimuli, which was a factor not reported in all experimental protocols. Another fact considered was the nonexistence of effects with other variables was the possible effect of short-term neuromodulation. When electrostimulation was applied to analyze possible reduction of pain, a neuraxial analgesic effect was found for ∼7 hours after the end of the intervention.²⁴ Therefore, the current authors suggest that future research should use intensity oscillation during electrostimulation application to avoid habituation, and perform electrostimulation at a delayed period after chemotherapy.

This is substantiated because there was a reduction in the mean number of episodes of acute nausea and delayed or acute vomiting, but not in the number of individuals who experienced these episodes. Nevertheless, the severity of nausea and vomiting did not have a protective effect. The current authors hypothesize that this was due to the absence of neuromodulation mechanisms applied to the thoracoabdominal nerves, resulting in the maintenance of an intense increase in intra-abdominal pressure when the 5-HT3 receptors were stimulated.¹⁹

However, the current review was limited by its small sample size, as well as large temporal lapses, varied methodologies, and varied quality among the included studies. Another factor to consider is the lack of studies on this topic, despite the frequent application of electrostimulation in clinical practice. Moreover, additional information sought from the authors of these studies proved insufficient to resolve the doubts that emerged during the construction of the meta-analysis.

Conclusion

This meta-analysis showed that the adopted protocols for electrostimulation of the PC 6 acupoint help control general emesis and are influenced directly by the effects on nausea in the acute period and vomiting in the different phases. However, the applied protocols need modifications. On the basis of this meta-analysis, the current authors provided certain recommendations to modify these protocols, thereby contributing directly to more-targeted future studies. Finally, the knowledge gained from this review will be useful to health professionals in providing evidence-based clinical management of patients receiving treatment for emesis induced by chemotherapy.

Appendix A1: Search Strategies for Literature Review

PubMed Search Strategy

• 1.((Transcutaneous electric nerve stimulation[MeSH Terms]) AND (Neoplasms[MeSH Terms])) AND (Antiemetics[MeSH Terms])
• 2.((Transcutaneous electric nerve stimulation[MeSH Terms]) AND (Neoplasms[MeSH Terms])) AND (Nausea[MeSH Terms])
• 3.((Transcutaneous electric nerve stimulation[MeSH Terms]) AND (Neoplasms[MeSH Terms])) AND (Vomiting[MeSH Terms])
• 4.((Transcutaneous electric nerve stimulation[MeSH Terms]) AND (Cancer)) AND (Antiemetics[MeSH Terms])
• 5.((Transcutaneous electric nerve stimulation[MeSH Terms]) AND (Cancer)) AND (Nausea[MeSH Terms])
• 6.((Transcutaneous electric nerve stimulation[MeSH Terms]) AND (Cancer)) AND (Vomiting[MeSH Terms])
• 7.((Electric stimulation therapy[MeSH Terms]) AND (Neoplasms[MeSH Terms])) AND (Antiemetics[MeSH Terms])
• 8.((Electric stimulation therapy[MeSH Terms]) AND (Neoplasms[MeSH Terms])) AND (Nausea[MeSH Terms])
• 9.((Electric stimulation therapy[MeSH Terms]) AND (Neoplasms[MeSH Terms])) AND (Vomiting[MeSH Terms])
• 10.((Electric stimulation therapy[MeSH Terms]) AND (Cancer)) AND (Antiemetics[MeSH Terms])
• 11.((Electric stimulation therapy[MeSH Terms]) AND (Cancer)) AND (Nausea[MeSH Terms])
• 12.((Electric stimulation therapy[MeSH Terms]) AND (Cancer)) AND (Vomiting[MeSH Terms])
• 13.((Electroacupuncture[MeSH Terms]) AND (Neoplasms[MeSH Terms])) AND (Antiemetics[MeSH Terms])
• 14.((Electroacupuncture[MeSH Terms]) AND (Neoplasms[MeSH Terms])) AND (Nausea[MeSH Terms])
• 15.((Electroacupuncture[MeSH Terms]) AND (Neoplasms[MeSH Terms])) AND (Vomiting[MeSH Terms])
• 16.((Electroacupuncture[MeSH Terms]) AND (Cancer)) AND (Antiemetics[MeSH Terms])
• 17.((Electroacupuncture[MeSH Terms]) AND (Cancer)) AND (Nausea[MeSH Terms])
• 18.((Electroacupuncture[MeSH Terms]) AND (Cancer)) AND (Vomiting[MeSH Terms])
• 19.((Transcutaneous acupoint electrical stimulation) AND (Neoplasms[MeSH Terms])) AND (Antiemetics[MeSH Terms])
• 20.((Transcutaneous acupoint electrical stimulation) AND (Neoplasms[MeSH Terms])) AND (Nausea[MeSH Terms])
• 21.((Transcutaneous acupoint electrical stimulation) AND (Neoplasms[MeSH Terms])) AND (Vomiting[MeSH Terms])
• 22.((Transcutaneous acupoint electrical stimulation) AND (Cancer)) AND (Antiemetics[MeSH Terms])
• 23.((Transcutaneous acupoint electrical stimulation) AND (Cancer)) AND (Nausea[MeSH Terms])
• 24.((Transcutaneous acupoint electrical stimulation) AND (Cancer)) AND (Vomiting[MeSH Terms])
• 25.((Relief band) AND (Neoplasms[MeSH Terms])) AND (Antiemetics[MeSH Terms])
• 26.((Relief band) AND (Neoplasms[MeSH Terms])) AND (Nausea[MeSH Terms])
• 27.((Relief band) AND (Neoplasms[MeSH Terms])) AND (Vomiting[MeSH Terms])
• 28.((Relief band) AND (Cancer)) AND (Antiemetics[MeSH Terms])
• 29.((Relief band) AND (Cancer)) AND (Nausea[MeSH Terms])
• 30.((Relief band) AND (Cancer)) AND (Vomiting[MeSH Terms])

BIREME (Lilacs e Medline^®) Search Strategy

• 1.(mh:(Transcutaneous electric nerve stimulation)) AND (mh:(Neoplasms)) AND (mh:(Antiemetics))
• 2.(mh:(Transcutaneous electric nerve stimulation)) AND (mh:(Neoplasms)) AND (mh:(Nausea))
• 3.(mh:(Transcutaneous electric nerve stimulation)) AND (mh:(Neoplasms)) AND (mh:(Vomiting))
• 4.(mh:(Transcutaneous electric nerve stimulation)) AND (mh:(Cancer)) AND (mh:(Antiemetics))
• 5.(mh:(Transcutaneous electric nerve stimulation)) AND (mh:(Cancer)) AND (mh:(Nausea))
• 6.(mh:(Transcutaneous electric nerve stimulation)) AND (mh:(Cancer)) AND (mh:(Vomiting))
• 7.(mh:(Electric stimulation therapy)) AND (mh:(Neoplasms)) AND (mh:(Antiemetics))
• 8.(mh:(Electric stimulation therapy)) AND (mh:(Neoplasms)) AND (mh:(Nausea))
• 9.(mh:(Electric stimulation therapy)) AND (mh:(Neoplasms)) AND (mh:(Vomiting))
• 10.(mh:(Electric stimulation therapy)) AND (mh:(Cancer)) AND (mh:(Antiemetics))
• 11.(mh:(Electric stimulation therapy)) AND (mh:(Cancer)) AND (mh:(Nausea))
• 12.(mh:(Electric stimulation therapy)) AND (mh:(Cancer)) AND (mh:(Vomiting))
• 13.(mh:(Electroacupuncture)) AND (mh:(Neoplasms)) AND (mh:(Antiemetics))
• 14.(mh:(Electroacupuncture)) AND (mh:(Neoplasms)) AND (mh:(Nausea))
• 15.(mh:(Electroacupuncture)) AND (mh:(Neoplasms)) AND (mh:(Vomiting))
• 16.(mh:(Electroacupuncture)) AND (mh:(Cancer)) AND (mh:(Antiemetics))
• 17.(mh:(Electroacupuncture)) AND (mh:(Cancer)) AND (mh:(Nausea))
• 18.(mh:(Electroacupuncture)) AND (mh:(Cancer)) AND (mh:(Vomiting))
• 19.(mh:(Transcutaneous acupoint electrical stimulation)) AND (mh:(Neoplasms)) AND (mh:(Antiemetics))
• 20.(mh:(Transcutaneous acupoint electrical stimulation)) AND (mh:(Neoplasms)) AND (mh:(Nausea))
• 21.(mh:(Transcutaneous acupoint electrical stimulation)) AND (mh:(Neoplasms)) AND (mh:(Vomiting))
• 22.(mh:(Transcutaneous acupoint electrical stimulation)) AND (mh:(Cancer)) AND (mh:(Antiemetics))
• 23.(mh:(Transcutaneous acupoint electrical stimulation)) AND (mh:(Cancer)) AND (mh:(Nausea))
• 24.(mh:(Transcutaneous acupoint electrical stimulation)) AND (mh:(Cancer)) AND (mh:(Vomiting))
• 25.(mh:(Relief band)) AND (mh:(Neoplasms)) AND (mh:(Antiemetics))
• 26.(mh:(Relief band)) AND (mh:(Neoplasms)) AND (mh:(Nausea))
• 27.(mh:(Relief band)) AND (mh:(Neoplasms)) AND (mh:(Vomiting))
• 28.(mh:(Relief band)) AND (mh:(Cancer)) AND (mh:(Antiemetics))
• 29.(mh:(Relief band)) AND (mh:(Cancer)) AND (mh:(Nausea))
• 30.(mh:(Relief band)) AND (mh:(Cancer)) AND (mh:(Vomiting))

Scielo Search Strategy

• 1.(ab:(*Transcutaneous electric nerve stimulation)) AND (ab:(Neoplasms)) AND (ab:(Antiemetics))
• 2.(ab:(*Transcutaneous electric nerve stimulation)) AND (ab:(Neoplasms)) AND (ab:(Nausea))
• 3.(ab:(*Transcutaneous electric nerve stimulation)) AND (ab:(Neoplasms)) AND (ab:(Vomiting))
• 4.(ab:(Transcutaneous electric nerve stimulation)) AND (ab:(Cancer)) AND (ab:(Antiemetics))
• 5.(ab:(Transcutaneous electric nerve stimulation )) AND (ab:(Cancer)) AND (ab:(Nausea))
• 6.(ab:(Transcutaneous electric nerve stimulation )) AND (ab:(Cancer)) AND (ab:(Vomiting))
• 7.(ab:(Electric stimulation therapy)) AND (ab:(Neoplasms)) AND (ab:(Antiemetics))
• 8.(ab:(Electric stimulation therapy)) AND (ab:(Neoplasms)) AND (ab:(Nausea))
• 9.(ab:(Electric stimulation therapy)) AND (ab:(Neoplasms)) AND (ab:(Vomiting))
• 10.(ab:(Electric stimulation therapy)) AND (ab:(Cancer)) AND (ab:(Antiemetics))
• 11.(ab:(Electric stimulation therapy)) AND (ab:(Cancer)) AND (ab:(Nausea))
• 12.(ab:(Electric stimulation therapy )) AND (ab:(Cancer)) AND (ab:(Vomiting))
• 13.(ab:(Electroacupuncture)) AND (ab:(Neoplasms)) AND (ab:(Antiemetics))
• 14.(ab:(Electroacupuncture)) AND (ab:(Neoplasms)) AND (ab:(Nausea))
• 15.(ab:(Electroacupuncture)) AND (ab:(Neoplasms)) AND (ab:(Vomiting))
• 16.(ab:(Electroacupuncture)) AND (ab:(Cancer)) AND (ab:(Antiemetics))
• 17.(ab:(Electroacupuncture)) AND (ab:(Cancer)) AND (ab:(Nausea))
• 18.(ab:(Electroacupuncture)) AND (ab:(Cancer)) AND (ab:(Vomiting))
• 19.(ab:(Transcutaneous acupoint electrical stimulation)) AND (ab:(Neoplasms)) AND (ab:(Antiemetics))
• 20.(ab:(Transcutaneous acupoint electrical stimulation)) AND (ab:(Neoplasms)) AND (ab:(Nausea))
• 21.(ab:(Transcutaneous acupoint electrical stimulation)) AND (ab:(Neoplasms)) AND (ab:(Vomiting))
• 22.(ab:(Transcutaneous acupoint electrical stimulation)) AND (ab:(Cancer)) AND (ab:(Antiemetics))
• 23.(ab:(Transcutaneous acupoint electrical stimulation)) AND (ab:(Cancer)) AND (ab:(Nausea))
• 24.(ab:(Transcutaneous acupoint electrical stimulation)) AND (ab:(Cancer)) AND (ab:(Vomiting))
• 25.(ab:(Relief band)) AND (ab:(Neoplasms)) AND (ab:(Antiemetics))
• 26.(ab:(Relief band)) AND (ab:(Neoplasms)) AND (ab:(Nausea))
• 27.(ab:(Relief band)) AND (ab:(Neoplasms)) AND (ab:(Vomiting))
• 28.(ab:(Relief band)) AND (ab:(Cancer)) AND (ab:(Antiemetics))
• 29.(ab:(Relief band)) AND (ab:(Cancer)) AND (ab:(Nausea))
• 30.(ab:(Relief band)) AND (ab:(Cancer)) AND (ab:(Vomiting))

Cochrane Library Search Strategy

• 1.(Transcutaneous electric nerve stimulation):kw AND (Neoplasms):kw AND (Antiemetics):kw
• 2.(Transcutaneous electric nerve stimulation):kw AND (Neoplasms):kw AND (“nausea”):kw
• 3.(Transcutaneous electric nerve stimulation):kw AND (Neoplasms):kw AND (“vomiting”):kw
• 4.(Transcutaneous electric nerve stimulation):kw AND (Cancer):kw AND (Antiemetics):kw
• 5.(Transcutaneous electric nerve stimulation):kw AND (Cancer):kw AND (“nausea”):kw
• 6.(Transcutaneous electric nerve stimulation):kw AND (Cancer):kw AND (“vomiting”):kw
• 7.(Electric stimulation therapy):kw AND (Neoplasms):kw AND (Antiemetics):kw
• 8.(Electric stimulation therapy):kw AND (Neoplasms):kw AND (“nausea”):kw
• 9.(Electric stimulation therapy):kw AND (Neoplasms):kw AND (“vomiting”):kw
• 10.(Electric stimulation therapy):kw AND (Cancer):kw AND (Antiemetics):kw
• 11.(Electric stimulation therapy):kw AND (Cancer):kw AND (“nausea”):kw
• 12.(Electric stimulation therapy):kw AND (Cancer):kw AND (“vomiting”):kw
• 13.(Electroacupuncture):kw AND (Neoplasms):kw AND (Antiemetics):kw
• 14.(Electroacupuncture):kw AND (Neoplasms):kw AND (“nausea”):kw
• 15.(Electroacupuncture):kw AND (Neoplasms):kw AND (“vomiting”):kw
• 16.(Electroacupuncture):kw AND (Cancer):kw AND (Antiemetics):kw
• 17.(Electroacupuncture):kw AND (Cancer):kw AND (“nausea”):kw
• 18.(Electroacupuncture):kw AND (Cancer):kw AND (“vomiting”):kw
• 19.(Transcutaneous acupoint electrical stimulation):kw AND (Neoplasms):kw AND (Antiemetics):kw
• 20.(Transcutaneous acupoint electrical stimulation):kw AND (Neoplasms):kw AND (“nausea”):kw
• 21.(Transcutaneous acupoint electrical stimulation):kw AND (Neoplasms):kw AND (“vomiting”):kw
• 22.(Transcutaneous acupoint electrical stimulation):kw AND (Cancer):kw AND (Antiemetics):kw
• 23.(Transcutaneous acupoint electrical stimulation):kw AND (Cancer):kw AND (“nausea”):kw
• 24.(Transcutaneous acupoint electrical stimulation):kw AND (Cancer):kw AND (“vomiting”):kw
• 25.(Relief band):kw AND (Neoplasms):kw AND (Antiemetics):kw
• 26.(Relief band):kw AND (Neoplasms):kw AND (nausea):kw
• 27.(Relief band):kw AND (Neoplasms):kw AND (“vomiting”):kw
• 28.(Relief band):kw AND (Cancer):kw AND (Antiemetics):kw
• 29.(Relief band):kw AND (Cancer):kw AND (nausea):kw
• 30.(Relief band):kw AND (Cancer):kw AND (“vomiting”):kw

EMBASE Search Strategy

• 1.'transcutaneous electric nerve stimulation':ab,ti AND neoplasms:ab,ti AND antiemetics:ab,ti
• 2.'transcutaneous electric nerve stimulation':ab,ti AND neoplasms:ab,ti AND nausea:ab,ti
• 3.'transcutaneous electric nerve stimulation':ab,ti AND neoplasms:ab,ti AND vomiting:ab,ti
• 4.'transcutaneous electric nerve stimulation':ab,ti AND cancer:ab,ti AND antiemetics:ab,ti
• 5.'transcutaneous electric nerve stimulation':ab,ti AND cancer:ab,ti AND nausea:ab,ti
• 6.'transcutaneous electric nerve stimulation':ab,ti AND cancer:ab,ti AND vomiting:ab,ti
• 7.'Electric stimulation therapy':ab,ti AND neoplasms:ab,ti AND antiemetics:ab,ti
• 8.'Electric stimulation therapy':ab,ti AND neoplasms:ab,ti AND nausea:ab,ti
• 9.'Electric stimulation therapy':ab,ti AND neoplasms:ab,ti AND vomiting:ab,ti
• 10.'Electric stimulation therapy':ab,ti AND cancer:ab,ti AND antiemetics:ab,ti
• 11.'Electric stimulation therapy':ab,ti AND cancer:ab,ti AND nausea:ab,ti
• 12.'Electric stimulation therapy':ab,ti AND cancer:ab,ti AND vomiting:ab,ti
• 13.electroacupuncture:ab,ti AND neoplasms:ab,ti AND antiemetics:ab,ti
• 14.electroacupuncture:ab,ti AND neoplasms:ab,ti AND nausea:ab,ti
• 15.electroacupuncture:ab,ti AND neoplasms:ab,ti AND vomiting:ab,ti
• 16.electroacupuncture:ab,ti AND cancer:ab,ti AND antiemetics:ab,ti
• 17.electroacupuncture:ab,ti AND cancer:ab,ti AND nausea:ab,ti
• 18.electroacupuncture:ab,ti AND cancer:ab,ti AND vomiting:ab,ti
• 19.'transcutaneous acupoint electrical stimulation':ab,ti AND neoplasms:ab,ti AND antiemetics:ab,ti
• 20.'transcutaneous acupoint electrical stimulation':ab,ti AND neoplasms:ab,ti AND nausea:ab,ti
• 21.'transcutaneous acupoint electrical stimulation':ab,ti AND neoplasms:ab,ti AND vomiting:ab,ti
• 22.'transcutaneous acupoint electrical stimulation':ab,ti AND cancer:ab,ti AND antiemetics:ab,ti
• 23.'transcutaneous acupoint electrical stimulation':ab,ti AND cancer:ab,ti AND nausea:ab,ti
• 24.'transcutaneous acupoint electrical stimulation':ab,ti AND cancer:ab,ti AND vomiting:ab,ti
• 25.'relief band':ab,ti AND neoplasms:ab,ti AND antiemetics:ab,ti
• 26.'relief band':ab,ti AND neoplasms:ab,ti AND nausea:ab,ti
• 27.'relief band':ab,ti AND neoplasms:ab,ti AND vomiting:ab,ti
• 28.'relief band':ab,ti AND cancer:ab,ti AND antiemetics:ab,ti
• 29.'relief band':ab,ti AND cancer:ab,ti AND nausea:ab,ti
• 30.'relief band':ab,ti AND cancer:ab,ti AND vomiting:ab,ti

Web of Science Search Strategy

• 1.(Transcutaneous electric nerve stimulation) AND TÓPICO: (Neoplasms) AND TÓPICO: (Antiemetics)
• 2.(Transcutaneous electric nerve stimulation) AND TÓPICO: (Neoplasms) AND TÓPICO: (Nausea)
• 3.(Transcutaneous electric nerve stimulation) AND TÓPICO: (Neoplasms) AND TÓPICO: (Vomiting)
• 4.(Transcutaneous electric nerve stimulation) AND TÓPICO: (Cancer) AND TÓPICO: (Antiemetics)
• 5.(Transcutaneous electric nerve stimulation) AND TÓPICO: (Cancer) AND TÓPICO: (Nausea)
• 6.(Transcutaneous electric nerve stimulation) AND TÓPICO: (Cancer) AND TÓPICO: (Vomiting)
• 7.(Electric stimulation therapy) AND TÓPICO: (Neoplasms) AND TÓPICO: (Antiemetics)
• 8.(Electric stimulation therapy) AND TÓPICO: (Neoplasms) AND TÓPICO: (Nausea)
• 9.(Electric stimulation therapy) AND TÓPICO: (Neoplasms) AND TÓPICO: (Vomiting)
• 10.(Electric stimulation therapy) AND TÓPICO: (Cancer) AND TÓPICO: (Antiemetics)
• 11.Electric stimulation therapy) AND TÓPICO: (Cancer) AND TÓPICO: (Nausea)
• 12.(Electric stimulation therapy) AND TÓPICO: (Cancer) AND TÓPICO: (Vomiting)
• 13.(Electroacupuncture) AND TÓPICO: (Neoplasms) AND TÓPICO: (Antiemetics)
• 14.(Electroacupuncture) AND TÓPICO: (Neoplasms) AND TÓPICO: (Nausea)
• 15.(Electroacupuncture) AND TÓPICO: (Neoplasms) AND TÓPICO: (Vomiting)
• 16.(Electroacupuncture) AND TÓPICO: (Cancer) AND TÓPICO: (Antiemetics)
• 17.(Electroacupuncture) AND TÓPICO: (Cancer) AND TÓPICO: (Nausea)
• 18.(Electroacupuncture) AND TÓPICO: (Cancer) AND TÓPICO: (Vomiting)
• 19.(Transcutaneous acupoint electrical stimulation) AND TÓPICO: (Neoplasms) AND TÓPICO: (Antiemetics)
• 20.(Transcutaneous acupoint electrical stimulation) AND TÓPICO: (Neoplasms) AND TÓPICO: (Nausea)
• 21.(Transcutaneous acupoint electrical stimulation) AND TÓPICO: (Neoplasms) AND TÓPICO: (Vomiting)
• 22.(Transcutaneous acupoint electrical stimulation) AND TÓPICO: (Cancer) AND TÓPICO: (Antiemetics)
• 23.(Transcutaneous acupoint electrical stimulation) AND TÓPICO: (Cancer) AND TÓPICO: (Nausea)
• 24.(Transcutaneous acupoint electrical stimulation) AND TÓPICO: (Cancer) AND TÓPICO: (Vomiting)
• 25.(Relief band) AND TÓPICO: (Neoplasms) AND TÓPICO: (Antiemetics)
• 26.(Relief band) AND TÓPICO: (Neoplasms) AND TÓPICO: (Nausea)
• 27.(Relief band) AND TÓPICO: (Neoplasms) AND TÓPICO: (Vomiting)
• 28.(Relief band) AND TÓPICO: (Cancer) AND TÓPICO: (Antiemetics)
• 29.(Relief band) AND TÓPICO: (Cancer) AND TÓPICO: (Nausea)
• 30.(Relief band) AND TÓPICO: (Cancer) AND TÓPICO: (Vomiting)

Scopus Search Strategy

• 1.( KEY (“transcutaneous electric nerve stimulation“) AND KEY ( neoplasms ) AND KEY ( antiemetics ) )
• 2.( KEY (“transcutaneous electric nerve stimulation“) AND KEY ( neoplasms ) AND KEY ( nausea ) )
• 3.( KEY (“transcutaneous electric nerve stimulation“) AND KEY ( neoplasms ) AND KEY ( vomiting ) )
• 4.( KEY (“transcutaneous electric nerve stimulation“) AND KEY ( cancer ) AND KEY ( antiemetics ) )
• 5.( KEY (“transcutaneous electric nerve stimulation“) AND KEY ( cancer ) AND KEY ( nausea ) )
• 6.( KEY (“transcutaneous electric nerve stimulation“) AND KEY ( cancer ) AND KEY ( vomiting ) )
• 7.( KEY ( “Electric stimulation therapy “ ) AND KEY ( neoplasms ) AND KEY ( antiemetics ) )
• 8.( KEY ( “Electric stimulation therapy “ ) AND KEY ( neoplasms ) AND KEY ( nausea ) )
• 9.( KEY ( “Electric stimulation therapy “ ) AND KEY ( neoplasms ) AND KEY ( vomiting ) )
• 10.( KEY ( “Electric stimulation therapy “ ) AND KEY ( cancer ) AND KEY ( antiemetics ) )
• 11.( KEY ( “Electric stimulation therapy “ ) AND KEY ( cancer ) AND KEY ( nausea ) )
• 12.( KEY ( “Electric stimulation therapy “ ) AND KEY ( cancer ) AND KEY ( vomiting ) )
• 13.( KEY (Electroacupuncture) AND KEY ( neoplasms ) AND KEY ( antiemetics ) )
• 14.( KEY (Electroacupuncture) AND KEY ( neoplasms ) AND KEY ( nausea ) )
• 15.( KEY (Electroacupuncture) AND KEY ( neoplasms ) AND KEY ( vomiting ) )
• 16.( KEY (Electroacupuncture) AND KEY ( cancer ) AND KEY ( antiemetics ) )
• 17.( KEY (Electroacupuncture) AND KEY ( cancer ) AND KEY ( nausea ) )
• 18.( KEY ( Electroacupuncture ) AND KEY ( cancer ) AND KEY ( vomiting ) )
• 19.( KEY (“Transcutaneous acupoint electrical stimulation”) AND KEY ( neoplasms ) AND KEY ( antiemetics ) )
• 20.( KEY (“Transcutaneous acupoint electrical stimulation”) AND KEY ( neoplasms ) AND KEY ( nausea ) )
• 21.( KEY (“Transcutaneous acupoint electrical stimulation”) AND KEY ( neoplasms ) AND KEY ( vomiting ) )
• 22.( KEY (“Transcutaneous acupoint electrical stimulation”) AND KEY ( cancer ) AND KEY ( antiemetics ) )
• 23.( KEY (“Transcutaneous acupoint electrical stimulation”) AND KEY ( cancer ) AND KEY ( nausea ) )
• 24.( KEY (“Transcutaneous acupoint electrical stimulation”) AND KEY ( cancer ) AND KEY ( vomiting ) )
• 25.( KEY (“Relief band”) AND KEY ( neoplasms ) AND KEY ( antiemetics ) )
• 26.( KEY (“Relief band”) AND KEY ( neoplasms ) AND KEY ( nausea ) )
• 27.( KEY (“Relief band”) AND KEY ( neoplasms ) AND KEY ( vomiting ) )
• 28.( KEY (“Relief band”) AND KEY ( cancer ) AND KEY ( antiemetics ) )
• 29.( KEY (“Relief band”) AND KEY ( cancer ) AND KEY ( nausea ) )
• 30.( KEY ( “Relief band”) AND KEY ( cancer ) AND KEY ( vomiting ) )

PEDro Search Strategy

• 1.Abstract & Title: antiemetic. Therapy: electrotherapies, heat, cold. Subdiscipline: oncology. Method: clinical trial.
• 2.Abstract & Title: nausea. Therapy: electrotherapies, heat, cold. Subdiscipline: oncology. Method: clinical trial.
• 3.Abstract & Title: vomiting. Therapy: electrotherapies, heat, cold. Subdiscipline: oncology. Method: clinical trial.
• 4.Abstract & Title: emesis. Therapy: electrotherapies, heat, cold. Subdiscipline: oncology. Method: clinical trial.

Author Disclosure Statement

No financial conflicts of interest exist.

Funding Information

No financial support was received for the research, authorship, and/or publication of this article.