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.