Association of sleep quality and urinary melatonin levels with endometrial cancer: A case control pilot study

Abstract

Endometrial cancer is the most common gynecologic malignancy globally. Recent studies suggest that alterations in circadian rhythm might be associated with an increased risk of endometrial carcinoma. To evaluate the association between sleep quality, urinary melatonin levels, and prevalence of endometrial cancer. A case control study was conducted among perimenopausal women with recently diagnosed endometrial cancer. Women with no history of cancer were recruited as controls. Sleep evaluation was done using the Pittsburgh Sleep Quality Index (PSQI). Urinary melatonin levels were measured using liquid chromatography tandem mass spectrometry methods. The sociodemographic variables (age, education, occupation, and diet) as well as the variables of PSQI scores and melatonin levels were compared between cases and healthy controls. The mean ± SD age of cases was 50.7 ± 11.2 (n = 18), and it does not differ significantly from the controls, 48.2 ± 2.6 (n = 18). The PSQI global scores mean (SD) among cases, 8.77 ± 3.76, was significantly higher as compared to controls, 6.27 ± 2.71 (P = 0.03). The sleep onset latency was significantly higher among patients (P = 0.002), and sleep duration scores are significantly different between cases and controls (P = 0.006). The melatonin level mean ± SD among cases, 6.72 ± 2.71 ng/mL, was significantly low as compared to controls, 12.38 ± 6.64 ng/mL (P = 0.006). Low melatonin levels along with sleep quality in endometrial carcinoma patients indicate that the malignancy might be associated with disturbances in the circadian rhythm.

Endometrial cancer is the most common gynecologic malignancy in high-income countries and the second most common in low- and middle-income countries. It was the second most common and the third leading cause of death due to gynecological cancer among women worldwide in 2022.[1] Several lifestyle risk factors are linked to development of endometrial cancer including working in night shift. Such alterations in circadian rhythm may be associated with an increased risk of endometrial carcinoma.[2]

Disruptions in circadian rhythm could lead to changes in the level of hormones such as melatonin, which is known to have cancer-protective properties such as apoptosis, antiangiogenic, antiproliferative, and metastasis-inhibitory mechanisms.[3] Melatonin secreted by the pineal gland has various physiological activities including sleep induction. Night shift work decreases serum melatonin levels promoting tumor development, as consistently suggested by animal and in vitro studies.[4,5] Previous studies establish the role of lower melatonin levels in women with endometrial cancer.[3,6] Modifiable factors such as working on rotating night shifts are associated with increased endometrial cancer risk among women.[2,7] Despite some literature quoting relation of sleep deprivation with endometrial cancer, there is no definite correlation established. Melatonin levels, if associated with causation of endometrial carcinoma, may play a significant role in prevention and therapy. The role of melatonin therapy in prevention and treatment of this disease might be explored. This study aimed to evaluate the effects of circadian rhythm and urinary melatonin levels as risk factors of endometrial carcinoma among Indian women. This is the first study reported from South Asian population.

MATERIAL AND METHODS

Study participants

Data collection for the case control study was carried out during January and February 2024. Subjects were recruited by convenience sampling from the department of obstetrics and gynecology of a tertiary care hospital in Delhi. Recruitment was based on the inclusion criteria: (i) women aged 40–60 years and (ii) newly diagnosed, untreated cases of endometrial carcinoma. Patients with other coexisting cancers or psychiatric conditions or on sleep medications based on medical history were excluded from the study. Age-matched healthy controls were recruited from the hospital staff who were not on sleep medication.

Data collection

After taking a written informed consent, complete information including sociodemographic and clinical history was recorded. Sleep evaluation was done using the Pittsburgh Sleep Quality Index (PSQI),[8] with the Hindi version of the PSQI, that is, the PSQI-H.[9] The PQSI is a self-administered tool that quantifies sleep disturbances and quality over a 1-month period. The Cronbach’s alpha for the PSQI is measured at 0.85, which indicates good internal consistency.

Urinary melatonin levels

First morning voided urine sample (30–50 mL) was collected in a sterile tube. The samples were stored at −20°C till analysis. Solid-phase extraction was used for extraction of urine samples. Measurement of melatonin was done using a liquid chromatography AB SCIEX Triple TOF 5600+ System, 4404854, Analyst TurboF2 1.7.1, Multiquant 3.0.3. The internal standards of 6-hydroxy Melatonin were used. The precursor and product ion were detected by high-resolution mass spectrometry in positive electrospray ionization (ESI) mode. All the data were acquired and processed using the AB Sciex Analyst TurboFlow 1.7.1 software.

Statistical analysis

The sociodemographic and PSQI variables were compared between cases and controls using nonparametric tests. Mann–Whitney U test was used to compare the sociodemographic features, sleep-related parameters, and urinary melatonin levels between cases and controls. Results with P < 0.05 were considered as statistically significant.

RESULTS

A total of 18 cases and controls each were recruited. The mean ± SD age of the cases, 50.7 ± 11.2 years, does not differ significantly from the controls, 48.2 ± 2.6 years. Other socioeconomics variables such as education level, occupation status, and dietary patterns were also comparable in both the groups. Among the cases, 77.8% (14) were of stage I, 11.1% (2) were stage III, and 11.1% (2) were stage IV.

The quality of sleep was measured using the PSQI. Figure 1 illustrates the variation in PSQI values of both groups. The cases had a significantly higher PSQI global scores as compared to controls (P = 0.03), indicating poorer sleep quality. As the graph demonstrates, a smaller number of cases has good sleep quality (indicated by a cutoff PSQI value of 5) as compared to controls. Further, the sleep onset latency was significantly higher among patients (P = 0.002) and sleep duration scores were significantly different between cases and controls (P = 0.006) [Table 1]. As per the PSQI scoring, the patients were categorized as good and poor sleepers. Among the cases, 12 (66%) were poor sleepers, while among controls, 9 (50%) were found to be poor sleepers.

Figure 1.

A graphical representation of the comparison of Global PSQI scores between endometrial carcinoma cases and healthy controls (n = 18)

Table 1.

Pittsburgh Sleep Quality Index (PSQI) scores and melatonin levels among endometrial carcinoma cases and healthy controls

Variables Mean (SD)	Cases (n=18)	Controls (n=18)	P*	t	95 % Confidence Interval	Effect Size (Cohen’s d)
Global PSQI score	8.77 (3.76)	6.27 (2.71)	0.03	2.24	0.21 to 4.79	0.01
Sleep duration score	1.94 (1.16)	1.5 (1.09)	0.006	1.14	−0.35 to 1.23	0.39
Habitual sleep efficiency score	0.5 (0.78)	0.11 (0.32)	0.06	1.91	−0.03 to 0.81	1.67
Sleep latency score	2.44 (1.08)	1.27 (1.07)	0.002	3.17	0.42 to 1.92	1.09
Sleep disturbance score	1.44 (0.51)	1.33 (0.48)	0.50	0.65	−0.24 to 0.46	0.22
Subjective sleep quality score	1.33 (0.59)	1.05 (0.53)	0.15	1.46	−0.11 to 0.67	0.49
Daytime dysfunction score	1.11 (0.96)	1.27 (0.95)	0.60	0.49	−0.83 to 0.51	0.17
Urinary melatonin levels (ng/mL)	6.72 (2.71)	12.38 (6.64)	0.006	3.25	−9.20 to−2.12	1.12

Urinary melatonin was detected by mass spectrometry using high-resolution multiple reaction monitoring (HRMRM) in positive electrospray ionization (ESI) mode. The retention time for 6 hydroxy melatonin and melatonin was obtained at 6.53 and 7.25 minutes, respectively. The melatonin level mean (SD) among cases, 6.72 ± 2.71 ng/mL, was found to be significantly low as compared to the controls, 12.38 ± 6.64 ng/mL (P = 0.006). In an earlier study in healthy volunteers, the 12-hour melatonin levels have been recorded as 29 ± 21 ng/12 hours.[10]

DISCUSSION

This study has compared the sleep quality and melatonin levels between patients with endometrial carcinoma and healthy controls. The main finding of the study is that those with endometrial carcinoma have a significantly higher PSQI global scores as compared to controls. Further, the sleep onset latency is significantly higher among patients and sleep duration scores are significantly different between cases and controls.

The retention time (RT) is a measure of the time taken for a solute to pass through a chromatography column till detection is reported at 6.53 and 7.25 minutes for 6 hydroxy melatonin and melatonin, respectively. This time varies for instruments and conditions.[10] The melatonin levels among cases are significantly lower as compared to the controls. An earlier study among breast cancer patients also found significantly lower levels among the patients.[11]

Limitations

These findings are limited by the small sample size and limited heterogeneity of the sample as cases were recruited from treatment-seeking population. However, the findings form a basis for further evaluation for factors linked to poor sleep quality, and lower melatonin levels among those with endometrial carcinoma. These findings are relevant in the context of knowledge that sleep quality has a strong impact on the quality of life of cancer patients and that female cancer patients usually more affected by such deficiencies.[12]

CONCLUSION

This study concludes that among endometrial carcinoma patients, the melatonin levels are significantly lower, and the sleep quality is significantly poorer. This indicates that the malignancy and associated bio-psycho-social mechanisms might be linked to disturbances in the circadian rhythm. Further research needs to be carried out on a large sample size using longitudinal observations and in a more diverse study population to bring out causal and mediatory factors.

Authors’ contributions

Conceived and designed the study: AK, RQ, SS, NS; Data collection: AK, SeS, NS; Data Analysis: AK, RQ, ArK, SeS; Manuscript writing, editing and revising: AK, RQ, SS, NS.

Ethical statement

The study protocol was approved by the institutional ethics committee of All India Institute of Medical Sciences, New Delhi, with Reference No. AIIMSA00046/26.10.2023,RT-07/13.12.2023. Dated 14.12.2023.

Conflicts of interest

There are no conflicts of interest.

Data availability statement

Data will be made available on reasonable request.

Funding Statement

Nil.