Complementary and alternative medicine use by glioma patients in Switzerland

Abstract

Background

During the course of disease, most glioma patients learn that there is no cure for their tumor. It is therefore not uncommon for patients or caregivers to seek complementary and alternative medicine (CAM) treatments. Patterns of CAM use vary across the globe, but little is known about the type of, and motivation for, CAM use in most countries.

Methods

Here we conducted a cross-sectional survey of CAM use in patients harboring gliomas of World Health Organization (WHO) grades II to IV at 3 specialized neuro-oncology centers in Switzerland.

Results

Of 208 patients who returned the survey, approximately half reported having used or using CAM. CAM use was associated with younger age. Patients suffering from WHO grade II gliomas were less likely to indicate CAM use. The leading motivation for CAM use was to contribute actively to the treatment of the disease. CAM use was commonly not counseled or supervised by a health care professional. Cost and issues of reimbursement were not an important factor in the decision against or for CAM use.

Conclusions

Physicians caring for glioma patients should be aware of and explore CAM use to better understand patients’ attitudes toward their disease, to provide counseling, and to identify potential interactions of CAM with standard treatments for gliomas.

The use of complementary and alternative medicine (CAM) is common in cancer patients. In a large meta-analysis covering studies from 18 countries, on average 40% of cancer patients reported current or previous use of CAM.¹ Common reasons for CAM use are a sense of control, management of symptoms, improvement of quality of life, or boosting the immune system.² Usually, CAM comprise therapies and products that are not considered to be part of conventional medicine. The definition of CAM for the Cochrane collaboration consists of a list of therapies or products within 5 categories suggested by the National Center for Complementary and Alternative Medicine: a) alternative medical systems, b) natural product-based therapies, c) energy therapy, d) manipulative and body-based methods, and e) mind-body interventions.³ An internationally harmonized definition of CAM is lacking, however, which makes comparisons of different studies on CAM difficult.⁴

Gliomas are the most common malignant primary brain tumors. According to the World Health Organization (WHO) classification of brain tumors, gliomas are categorized from grade I to grade IV to inform about the biological behavior of an individual tumor and thus patient prognosis.⁵ While gliomas of WHO grade I are potentially curable by complete resection, gliomas of WHO grades II to IV typically cannot be cured. Prognosis is determined by age, performance status, molecular markers, and therapeutic interventions. Yet, in glioblastoma, the most aggressive primary brain tumor in adults, the median survival is still in the range of 1 year on a population level.⁶ Given the dismal prognosis, impairment by neurological deficits and possible side effects from conventional therapies, many glioma patients seek alternative treatments. Only a few studies have addressed the use of CAM in brain tumor patients. According to these surveys, 24% to 77% of patients with different types of primary brain tumors including gliomas reported the use of CAM.^7–11 In clinical practice CAM use may not always be reported by patients or systemically asked about by health care professionals (HCPs).¹² In a cross-sectional questionnaire-based survey published by the German Glioma Network in 2010, 40% of glioma patients indicated the use of CAM.⁹ CAM was applied to support rather than to replace conventional therapies and because patients wanted to actively contribute to the treatment themselves. CAM use is likely to vary by region and country, as does its reimbursement by types of health insurance.¹ For Switzerland, such investigations of glioma patients do not exist. Accordingly, here we describe the extent of, and motivation for, CAM use in a cohort of 208 glioma patients from Switzerland.

Patients and Methods

This study was a prospective, cross-sectional, descriptive survey on the use of CAM. Between October 2012 and October 2015, a questionnaire was distributed to patients suffering from gliomas treated at the brain tumor centers at the University Hospitals Zurich and Basel and at the Cantonal Hospital in Aarau in Switzerland. The questionnaires were handed out at patient appointments and 208 patients across the 3 centers participated. The participants were asked to fill out the questionnaire by themselves and by far most patients did so at the same appointment. The return rates were 93% (63/68) for Aarau, 86% (126/146) for Zurich, and not available for Basel. Eligibility criteria included the diagnosis of a glioma of WHO grade II to IV and age ≥ 18 years at inclusion. Patients were not approached for participation if severe neuropsychological deficits were clinically apparent. A similar questionnaire as used here has previously been used in a cohort of glioma patients from the German Glioma Network.⁹ The questionnaire comprised multiple-choice as well as categorical response questions and open-response options. The topics included sources of information on tumor treatment in general and especially on CAM; types of CAM used; reasons for use of CAM; benefits, adverse effects, and satisfaction perceived from CAM use; lead of the CAM treatment and communication with HCPs; costs of CAM and reimbursement; education; employment; and marital status. In this manuscript, HCP refers to all kind of medical professionals involved in conventional treatment, like oncologists, radiation oncologists as well as general practitioners. The questionnaire is provided as online resource 1.

The study adhered to the ethical requirements of the Declaration of Helsinki and was approved by the local ethics committees of the 3 participating centers with the Cantonal Ethics committee of Zurich as the leading ethics committee (KEK-ZH 2012-0070). The participants received oral and written information prior to giving informed consent.

Statistical analysis of demographic data and of the differences between patients using CAM or not was performed with SPSS software version 25 for Mac (IBM, Armonk, NY, USA) using the chi-squared² and the Mann-Whitney U test. Analysis was conducted using a significance level of 5%.

Results

Characteristics of Study Participants

A total of 208 glioma patients participated: 130 men (62%) and 78 women (38%). Median age was 53 years (range, 21-80 years). The patients suffered from a glioma of WHO grade II (n = 64, 31%; median age 49), grade III (n = 61, 29%; median age 45), or grade IV (n = 83, 40%; median age 60). At the time of the survey, 86 patients (41%) had experienced recurrence of disease at least once. Most patients reported an educational level higher than sole job formation (n = 115; 55%), being married or living in a partnership (n = 157; 75%), and having children (n = 143; 69%) (Table 1). Overall, the patients participated in the survey at a median of 31 months following glioma diagnosis (range, 1.7-329 months). Patients suffering from glioma of WHO grade II had the largest interval from diagnosis to participation in this survey (median 88.3 months) compared to WHO grade III (median 32.6 months) and WHO grade IV tumors (median 15 months).

Table 1.

Patient Characteristics

Patients	208
Patient characteristics	Patient number	%
Age, years
Median	53
Range	21-80
Sex
Male	130	62.5
Female	78	37.5
Glioma (WHO grade)
II	64	30.8
III	61	29.3
IV	83	39.9
Education Level
Primary school	7	3.3
Job formation degree	80	38.3
Higher education	68	32.5
University degree	47	22.5
Other	6	2.9
Marital status
Single	33	15.9
Married/Partnership	157	75.5
Divorced	14	6.7
Widowed	2	1.0
No answer	2	1.0
Children
Yes	143	68.8
No	63	30.3
No answer	2	1.0
CAM use
Yes	101	48.6
No	107	51.4

Abbreviations: CAM, complementary and alternative medicine; WHO, World Health Organization.

Alternative Therapy Use

A total of 101 patients (49%) reported the use of CAM for glioma treatment in the past, and 67 of these patients (66%) had used CAM within the last 12 months. Among the CAM users 41 were female and 60 were male, corresponding to 53% of all women and 46% of all men participating in the study (P > .05). Younger patients were more likely to report the use of CAM (P = .004): Median age of CAM users was 49 compared to 56 years for nonusers. In the age group < 50 years, 52 of 88 patients (59%) were CAM users, while in the age group ≥ 50 years this was the case for only 49 out of 120 patients (41%) (P = .009) (Figure 1A). CAM use was not associated with WHO grade when calculated across all grades (P = .054). However, patients suffering from WHO grade II glioma were less likely to indicate the use of CAM compared to WHO grades III and IV (P = .033). Within the group of WHO grade III gliomas, 36 of 61 (59%) patients reported the use of CAM, while CAM users (n = 41) and nonusers (n = 42) were evenly distributed among WHO grade IV glioma patients (Figure 1B). No statistically significant difference was detected between CAM users and nonusers regarding educational level, status of recurrent disease, or time from diagnosis in our patient cohort.

Fig. 1.

Age and World Health Organization (WHO) Grade Dependence of Complementary and Alternative Medicine (CAM) Use. A, Distribution of patients grouped by age: < or ≥ 50 years of age. B, CAM use by WHO grade (A, B: CAM use, black bars; CAM nonuse, gray bars).

Pathways to Complementary and Alternative Medicine Use

Patients using CAM most often received suggestions about CAM from friends (n = 52; 27%) and family members (n = 48; 25%, multiple answers possible); 25 patients (13%) also indicated that a physician suggested CAM use. While the internet (n = 18; 9%) and other media were regularly mentioned, self-help groups (n = 2; 1%) played only a marginal role for inspiration on CAM use (Table 2). In contrast, 35% (n = 39) of respondents to this question indicated not having received counseling on CAM. If counseling took place, CAM practitioners and family doctors were most often mentioned (n = 19; 17% each) (Table 3). In line with counseling on CAM use by HCPs, only to a limited extent, about 29% (n = 41) of the respondents reported they carried out the CAM therapy by themselves (Supplementary Table 1).

Table 2.

Sources of Inspiration for Complementary and Alternative Medicine (CAM) Use

Inspiration for CAM use by	Responses
	Absolute number	%
Friends	52	27.2
Family members	48	25.1
Physicians	25	13.1
Press and books	19	9.9
Internet	18	9.4
CAM practitioners	14	7.3
Other patients	5	2.6
Nurses	3	1.6
Television	3	1.6
Self-help groups	2	1.0
Radio	1	0.5
Other	1	0.5

In total 192 responses were received; more than 1 response was possible.

Table 3.

Counseling on Complementary and Alternative Medicine (CAM)

Counseling on CAM by	Responses
	Absolute number	%
None	39	34.8
Family doctor	19	17.0
CAM practitioner	19	17.0
Oncologist	9	8.0
Neurologist	8	7.1
Neurosurgeon	7	6.3
Other	5	4.5
Psychotherapist	3	2.7
Radiation-Oncologist	3	2.7

In total 112 responses were received; more than 1 response was possible.

Types of Complementary and Alternative Medicine Used

The participants in this survey were asked to choose types of CAM they were using for the treatment of glioma from a predefined list. Additionally, the patients were invited to indicate types of CAM that were not listed. Most commonly reported CAM were psychological methods (n = 41; 12%), followed by homeopathy (n = 33; 10%) and vitamins (n = 31; 9%). Table 4 gives an overview on the different types of CAM used by the study participants.

Table 4.

Types of Complementary and Alternative Medicine (CAM) Used by Glioma Patients

Type of CAM	Responses
	Absolute number	%
Psychological methods	41	12.2
Psychotherapy	18	5.4
Relaxation methods	10	3.0
Imagination	6	1.8
Hypnosis	5	1.5
Other	2	0.6
Homeopathy	33	9.8
Vitamins	31	9.2
Multivitamins	14	4.2
Vitamin C	8	2.4
Vitamin A	4	1.2
Vitamin E	4	1.2
Beta-carotene	1	0.3
Boswellia acids	30	8.9
Mistletoe	26	7.7
Phytotherapy	25	7.4
Acupuncture	20	6.0
Anthroposophic medicine	18	5.5
Traditional Chinese medicine	16	4.8
Minerals	13	3.9
Detoxification	13	3.9
Magic healing	10	3.0
Bach flower remedies	9	2.7
Bioresonance	7	2.1
Bowel remedial action	6	1.8
Shielding (earth radiation/water veins)	4	1.2
Neural therapy	3	0.9
Hyperthermia	3	0.9
Ozone therapy	3	0.9
Blood retransfusion	2	0.6
Oxygen multistep therapy	2	0.6
Live cell therapy	2	0.6
Peptides	1	0.3
Enzymes	1	0.3
Thymus extracts	1	0.3
Othera	16	4.8

In total 338 responses; more than 1 response was possible.

^aIn addition to the items above that could be chosen on the questionnaire, the following items were indicated by the responding patients: ketogenic diet, vegetables, orthomolecular nutrition, tyramine restricted diet, green tea, colostrum, vitamin D, Ayurveda, osteopathy, neurofeedback, prayer (n = 2), shiatsu, massage, yoga, or energy healing.

Reasons for Use of Complementary and Alternative Medicine

Among the patients indicating CAM use, the motivational items the respondents most frequently agreed with were to support conventional therapy (n = 85), to actively contribute to the treatment (n = 80), to harness the body’s defenses (n = 81), and to have tried everything possible (n = 77; multiple answers possible). Regarding the motivational item to use CAM “because I am highly convinced,” only 63 respondents agreed, while 22 were not sure about and 8 even disagreed with this item. The motivational items mostly disagreed with were “because doctors don’t have enough time for me” (n = 85) and “because conventional methods are frightening” (n = 68) (Supplementary Figure 1).

Patients not using CAM were invited to write in their reasons. The answers indicated a lack of information on CAM in general and on efficacy and risks of CAM. Moreover, 12 patients expressed a high trust in conventional medicine and no need to use CAM.

Perceived Effects of Complementary and Alternative Medicine

A majority of CAM users attributed beneficial effects of CAM on their emotional (n = 67; 70%) or physical (n = 69; 71%) condition (Supplementary Table 2). Asked about side effects of CAM use, a majority of the respondents indicated no side effects (n = 91; 92%). Reports on mild (n = 7; 7%) to moderate (n = 1; 1%) side effects comprised tiredness, loss of appetite, malaise, hair loss, stomach trouble, and muscle soreness. Overall, CAM users reported a high rate of satisfaction with the success of the CAM they were applying. Twenty-three respondents (24%) indicated they were “completely,” 30 (31%) were “very,” and 35 (36%) were “satisfied.” Six respondents (6%) were “less satisfied” and only 3 (3%) reported being “unsatisfied.”

Economic Aspects of Complementary and Alternative Medicine Use

A majority of CAM users (n = 95; 94%) responded to the question about the average cost of CAM per month. Of these, 19 (20%) indicated spending less than 50 Swiss Francs (CHF), 31 (32%) between 50 and 100 CHF, 33 (34%) between 100 and 500 CHF, 2 (2%) between 500 and 1000 CHF, and 2 (2%) more than 1000 CHF per month. Furthermore, 94% (n = 95) of the CAM users gave information on reimbursement. Within the Swiss health care system, basic health insurance is obligatory for all residents living in Switzerland. In addition to the basic insurance, residents are free to choose and pay for additional private health insurance products, usually covering a wider range of health care products and services. Thirty-six respondents (38%) indicated not having received any reimbursement of the costs for CAM by their health insurance. One of these patients indicated no reimbursement for a boswellia acid product but for psychotherapy by his basic insurance. For 10 (11%) respondents at least a part of the costs was covered by basic, for 42 respondents (42%) by private, and for 7 (7%) by basic and private insurance. Only 56 CAM users (55%) estimated the proportion of reimbursement of CAM costs by health insurance. Thirteen respondents (23%) indicated a full reimbursement of CAM costs, 33 (59%) indicated reimbursement for more than 50%, and 9 (16%) for less than 50% of CAM costs. One respondent using different types of CAM indicated full for 1 and more than 50% reimbursement for another CAM. All patients, CAM users and nonusers, were asked the importance of reimbursement for their decision to use CAM or not in general and regarding a special type of CAM. Only a minority of responding CAM users (n = 29; 30%) as well as nonusers (n = 65; 37%) indicated the importance of getting CAM costs reimbursed for their decision to use or not to use CAM, respectively.

Discussion

This is the first survey on the use of CAM in glioma patients in Switzerland and 1 of few studies examining this issue in brain tumor patients in general. Forty-nine percent of the 208 participating patients suffering from gliomas of WHO grades II to IV reported the use of CAM.

In 4 studies from the United States and Canada, rates of CAM users among patients with primary brain tumors varied between 24% and 74% of participants.^7–11 These studies were not restricted to glioma patients and several types of primary brain tumors or only glioblastoma were included, which limits comparability. However, the rate of CAM use of 49% in this survey was somewhat higher than the 40% reported in Germany in a sample published in 2010⁹ using a very similar questionnaire. Considerable differences among studies in the rates of CAM use can be found in the literature on cancer patients in general. In a large meta-analysis, approximately 40% of cancer patients reported current or previous use of CAM therapies with a range of 9% to 88% in different studies.¹ Factors possibly influencing this high variability include inconsistent definitions of CAM, selection bias in specialized cancer centers, recall bias in retrospective analyses, and a lack of standardized tools to assess CAM use in the cancer population. Moreover, cross-sectional data might not entirely reflect the use of CAM in highly dynamic diseases like cancer. A larger prospective, longitudinal evaluation of CAM use in glioma patients might help to clarify the trajectories of CAM use throughout the course of the disease. Table 5 gives a comparative overview on the relevant studies published on CAM use in brain tumor patients.

Table 5.

Comparison of Surveys on the Use of Complementary and Alternative Medicine (CAM) in Brain Tumor Patients

	Verhoef et al 11	Fox et al 8	Armstrong et al 7	Heese et al 9	Mulpur et al 10	Present Survey
Year of Publication	1999	2006	2006	2010	2015	2018
Participants	167	186	101	622	470	209
Region	Alberta, Canada	USA (29 states) and Canada	Houston, TX, USA	Germany	USA	Switzerland
Tumor Types	LGG (28%), MG (26%), meningioma (16%), glioblastoma (14%), MB (3%), other (12%)	Gliomas of WHO grade III and IV	Glioblastoma (39), AG (31), LGG (19), PCNSL (3), MB (2), other (7)	Gliomas of WHO grades I to IV	Glioblastoma	Gliomas of WHO grades II to IV
Assessment	Prospective, questionnaire- based	Secondary analysis of Glioma Outcomes Project	Prospective, questionnaire- based	Questionnaire mailed to patients from German Glioma Network	Structured interview on nutritional or herbal supplements	Prospective, questionnaire- based
CAM Use	24%	32%	54%	40%	77%	49%
CAM Use Associated With	Younger age, higher income, no association with QoL, KPS or type of tumor	Younger age, female, college education	Higher KPS, no association with QoL or WHO grade	Younger age, female, university degree, no association with WHO grade	Younger age, female, lower KPS less likely, no association with education	Younger age, less likely glioma of WHO grade II, no association with gender or education
Top 3 CAM Used	Herbs, mind-body therapies, animal-/ vegetable-derived products	Meditation, vitamins, herbs	Prayer, vitamins, herbs	Homeopathy, vitamins, psychological methods	Vitamin C, vitamin E, zinc	Psychological methods, homeopathy, vitamins
Main Sources of Inspiration for CAM Use	Family and friends	NR	NR	Friends, physicians, family	NR	Friends, family, physicians
Main Motivations to Use CAM	Wish for patient- focused treatment, take charge of their care	NR	Being proactive in fighting the disease, improving QoL, minimizing side effects	To do something for the treatment by myself, to build up body resistance, to support conventional therapy, to have tried everything possible	NR	To support conventional therapy, to do something for the treatment by myself, to build up body resistance, to have tried everything possible
Perceived Effects of CAM	73% positive effects	NR	88% expressed satisfaction	60% attributed improvment of general condition to CAM	NR	69% attributed improvment of emotional, 70% of physical condition to CAM
Side Effects of CAM	10%, most commonly bad breath	NR		4.9% minor side effects	NR	9% mild to moderate side effects
Doctor’s Awareness of CAM Use	23% not aware, 33% not sure	NR	74% not aware	NR	NR	NR
CAM Use and Survival	NR	NR	NR	NR	Vitamin D, herbal supplementsa	NR

Abbreviations: AG, anaplastic glioma; LGG, low-grade glioma; MB, medulloblastoma; MG, malignant glioma; NR, not reported; PCNSL, primary central nervous sytem lymphoma; QoL, quality of life: USA, United States of America; WHO, World Health Organization.

^aIn this study, a possible association of intake of vitamin D or herbal supplements with increased survival is described, a finding that needs to be confirmed in further studies.

In the present study, CAM use was associated with younger age, consistent with previous studies.^8,9,11 In contrast to the results from the German Glioma Network⁹ revealing no association between CAM use and WHO grade, patients suffering from WHO grade II glioma were less likely to indicate CAM use in the present study. Interestingly, the patients within the group of WHO grade III glioma displayed the highest proportion of CAM use in our cohort. In a recent survey restricted to patients diagnosed with glioblastoma, the participants reported CAM use in 74% of cases,¹⁰ which exceeds the rates reported in all other aforementioned studies in brain tumors. The result from this survey suggests a higher rate of CAM use in glioblastoma patients with particularly poor prognoses, which could indicate increased pressure on this group of patients to seek alternatives to conventional treatment. Nevertheless, increasing CAM use with increasing grade of malignancy is not supported by the other studies in glioma patients, including the present survey (Table 5).^7–11 The cross-sectional nature of these surveys, however, prohibits drawing definite conclusions.

In contrast to the results from the German Glioma Network,⁹ female gender and higher education were not correlated with CAM use in Swiss glioma patients, although the educational level of the patients in our cohort was comparable. This might indicate local differences in the use of CAM even in countries in close geographical and cultural proximity. Moreover, a higher educational level might just reflect a higher economic status permitting CAM use, which could be less important in Switzerland. In the present survey, only a minority of participants indicated the importance of getting CAM costs reimbursed for their decision to use or not to use CAM. However, the above-average household income in Switzerland compared to other Organisation for Economic Co-operation and Development countries limits generalization of this finding. According to the Swiss Federal Office for Statisics, the pretax median income in 2016 in Switzerland in the private sector was 6230 CHF/month (https://www.bfs.admin.ch/bfs/de/home/statistiken/arbeit-erwerb/loehne-erwerbseinkommen-arbeitskosten/lohnniveau-schweiz.html). Regarding reimbursement, 19% of respondents to these questions got reimbursed at least in part by obligatory basic health insurance, while 38% did not get reimbursed at all. Most reimbursements were performed on the basis of private insurance products (49% of respondents, 7% overlap with basic insurance). The situation in Switzerland is of particular interest. From 2012 on, basic health insurance plans are obliged to cover the costs of defined complementary therapies: homeopathy, anthroposophic medicine, phytotherapy, and traditional Chinese medicine. In the present survey, we did not note an unusual preponderance of these CAM modalities compared to the study from Germany,⁹ and these modalities are per se already popular. However, a future shift of CAM use toward these therapies being reimbursed by basic insurance cannot be excluded. Overall, across the studies on CAM use in primary brain tumors including glioma, younger age seems to be the most consistent factor predicting CAM use (Table 5).

The patient population studied here using CAM most commonly indicated doing so to support conventional therapy, to actively contribute to treatment, to harness the body’s defenses, and to have tried everything possible. These motivational items are similar to those found in other reports on this topic in brain tumors^7,9,11 or in cancer in general,^2,13,14 revealing a more holistic patient view on cancer. It is worthwhile to consider unmet needs behind these motivations to use CAM. In the general population, many citizens confer positive attitudes toward CAM, and there is a wish for reliable and trustworthy information by HCPs to support informed decision making.¹⁵ In our survey as in others,^9,11 however, family and friends were the main sources of inspiration and information on CAM. As 1 consequence, a considerable proportion of CAM users in this survey were in charge of CAM use on their own (29%), without proper counseling by HCPs (35%). There is an obvious lack of communication between HCPs and brain tumor patients,^7,11 harboring risks for the patients and lost opportunities. In the general cancer population, up to 77% do not disclose CAM use to their HCPs.¹² This lack of communication can stress the therapeutic relationship.¹⁶ Biological compounds might confer side effects and interact with conventional treatments, which should be discussed with patients.^17–19 Moreover, certain CAM products do not undergo regulated quality control and might contain toxic byproducts like high concentrations of heavy metals.²⁰ In contrast, patient-centered communication including discussion on CAM might enhance patient satisfaction with care, reduce distress, and could even improve adherence to conventional treatment.^2,14,16,21 Reasons for patients to be reluctant to discuss CAM with their HCPs include fear of negative response or anticipation of differing views about CAM between patients and HCPs.^22–24 Interestingly, in a survey of HCPs in the cancer field, a majority of HCPs reported little knowledge about CAM and felt unprepared to address CAM in the clinical context by themselves.¹⁴ Nonetheless, 90% of HCPs in the latter study expressed interest in receiving further CAM education. To facilitate access to information on CAM, cancer centers have started to develop integrative oncology programs to bring together and discuss concepts of conventional medicine and CAM. While this necessitates potentially controversial discussions in the presence of patients and caregivers, this type of integrative oncology also offers the chance to perform rigorous research on CAM and to potentially introduce scientifically supportable elements of CAM into clinical practice or to reveal potential harm of CAM.²⁵ Nowadays, CAM is a term that “lumps together the highly implausible with the plausible”²⁵ and patients are to a considerable extent left alone with their needs. The negligible role of self-help groups in our survey reflects the virtual absence of such organizations in Switzerland and the very limited impact of foreign organizations on Swiss glioma patients.

One limitation of this study is that all patients were recruited in brain tumor centers affiliated with hospitals, and all of these patients underwent conventional treatment for their tumors and some patients participated in clinical trials, including 12 patients in our cohort indicating CAM use. Thus, patients used CAM in addition to conventional treatment, and a selection bias cannot be excluded.

Overall, a considerable number of patients suffering from glioma use CAM, and this was true for the glioma patients in the present study as well. HCPs should be aware of potential CAM use and should actively discuss this issue with their patients.

Funding

This work was supported by a grant from the Swiss Brain Tumor Foundation.

Conflict of interest statement. None declared.