Discussion
Several cancers are associated with circadian clock dysfunction, highlighting the connection between circadian rhythm dysregulation and oncogenesis (29). Epidemiological studies have linked cancers to night shift work and light pollution that disrupt chronotype (2, 30). In mice, dysregulated circadian gene expression may cause lymphoma, osteosarcoma, and hepatocellular carcinoma (HCC), according to Kettner et al. (31). Jiang et al. reported that circadian gene disruption is associated with the onset of HCC (11). Methylation of single nucleotide polymorphisms (SNPs) or clock gene promoters is a known molecular mechanism (30). Consideration of this issue could lead to cancer prevention and treatment in the future.
In our study, there was no significant correlation between chronotype and gender (P =0.629), age (P =0.135), marital status (P =0.263), occupation (P =0.931), or education level (P =0.899). Definitive and moderate morning types exhibited higher age means than neither and moderate evening types. This finding is consistent with the findings of Montaruli et al., who observed that older adults are typically morning types, possibly due to age-related sleep shortness, whereas younger adults are commonly evening types (32). Furthermore, there is no correlation between age and gender, and circadian rhythm (32, 33, 34). Some studies suggest that there may be gender differences in circadian types due to housework, grooming, and breakfast preparation. In a cohort study conducted by Ramin et al., the average age and BMI of the participants were 59.2 y and 27.5 kg/m2, respectively, and the most prevalent chronotype was definitely morning type, while neither type was the least prevalent (35).
Neither type increased the risk of breast cancer among participants, but the difference was not statistically significant (35). In our study, breast cancer was the most prevalent type, and neither type comprised the majority, consistent with a previously published study. A dysregulated circadian rhythm in neither species, possibly leading to cancer, may explain this finding. Our study’s mean age and BMI were 49 and 25.09 kg/m2, respectively. All of the participants in the current study were cancer patients; some were in advanced stages and suffered from cachexia, which could explain the differences in BMIs. Bhar et al. found that evening types have a higher BMI, FBS, and HbA1c, resulting in less physical activity, unhealthy eating habits, and sleep disturbances that lead to T2DM (33, 36).
In contrast to our study, the mean BMI is higher for morning types, but no significant difference was observed between circadian types (P =0.317). The participants lacked comorbidities such as diabetes, and we did not evaluate their physical activity and dietary habits; as previously mentioned, some patients were in the cachectic phase. Chronotype was not significantly associated with duration as a cancer patient (P =0.855) or hospital admission (P =0.250). The neither and moderately evening types developed cancer sooner, were hospitalized more frequently, experienced fatigue and weakness, and were in advanced stages; consequently, these groups exhibit a lower BMI. The present study observed normal distribution for chronotype, and the mean MEQ score was 56.6 ± 6.34 (41-74). Neither type was the most chronotype, with the moderately evening type being the least. No evening-only types were detected. In a case-control study conducted by Di Somma et al., the mean MEQ score of craniopharyngioma patients was 47.8 ± 12.6 (34).
Most participants were morning types, and the minority were evening types (34). Definitive and moderate morning types were considered one group, and evening types were considered a second (34). Based on the results, females were predominantly evening and intermediate types, while males were primarily morning types. Different MEQ means and scores may result from the sample size, study design, and various types of cancer. In line with our findings, Kanagarajan et al. demonstrated that the MEQ distribution in bipolar patients aged 25 to 66 was normal, the mean score was 49.2 ± 10.4 (24-74), neither type was the most chronotype, and circadian rhythm was not significantly associated with age and gender (37). The correlation between circadian rhythm and surgery (P =0.933), chemotherapy (P =0.565), and radiotherapy (P =0.326) were not statistically significant.
Most patients who received chemotherapy and radiotherapy were neither morning nor evening types, whereas morning types had more chemotherapy sessions. Multiple studies have suggested that a higher MEQ score for morning types is associated with fewer chemotherapy-related side effects, such as nausea and vomiting (32). Cancer patients were the subject of a case-control study by Sultan et al. (38). The participants’ mean age was 46.67 ± 12.51 y (38). Similar to our research, the majority and minority circadian rhythms were neither morning nor evening. The MEQ score was negatively correlated with chemotherapy-induced nausea, vomiting, and diarrhea (38). Unfortunately, we did not assess the side effects of chemotherapy or radiotherapy. Hematologic and non-hematologic cancers (P =0.999), palliative therapy or treatment (P =0.262), treatment method combinations such as chemotherapy + radiotherapy (P =0.457), chemotherapy + surgery (P =0.794), radiotherapy + surgery (P =0.500), and chemotherapy + radiotherapy + surgery (P =0.738) were not significantly correlated to chronotype. The majority of participants in these groups fell into neither category.
Some research indicates that chronochemotherapy and chronoradiotherapy may improve cancer patients’ survival and response rate (18). Consequently, chronomodulated chemotherapy or radiotherapy sessions compatible with circadian rhythm may be advantageous to the treatment process (18). Although a disorganized circadian rhythm may result in carcinogenesis, cancer treatments may alter the circadian type. Comparing the chronotype of various cancers requires additional research.