Relationship of Sleep Duration and Annual Changes in Sleep Duration with the Incidence of Gastrointestinal Cancers: A Prospective Cohort Study
Introduction Gastrointestinal (GI) cancers, including colorectal, gastric, liver, gallbladder, pancreatic, and esophageal cancers, represent a significant global health burden. In China, the incidence and mortality rates of GI cancers are particularly high, accounting for a substantial proportion of global cases. The epidemiology of GI cancers in China is complex, influenced by factors such as geographic location, sex, age, and cancer type. Identifying modifiable risk factors is crucial for reducing the burden of these cancers. Traditional risk factors include diabetes, tobacco smoking, obesity, and high vitamin D status. Recent studies have also explored the potential role of sleep in cancer development.
Sleep is a fundamental human need, and its relationship with cancer has been a subject of increasing interest. While some studies have suggested associations between sleep duration and cancer risk, the evidence remains inconsistent. Previous research has primarily focused on sleep duration at a single time point, with limited exploration of how changes in sleep duration over time may influence cancer risk. This study aims to examine the association between baseline sleep duration, annual changes in sleep duration, and the incidence of GI cancers in a large population-based cohort.
Methods The study utilized data from the Kailuan cohort, a prospective dynamic cohort study conducted in Tangshan City, Northern China. The cohort included 138,150 participants aged 18 years and older, recruited from 11 affiliated hospitals of the Kailuan Group. Participants underwent standardized questionnaire interviews and physical examinations starting in May 2006. The study excluded individuals with a prior cancer diagnosis and those without baseline sleep duration information, resulting in 123,495 participants for baseline sleep duration analysis. Further exclusions were made for the analysis of annual changes in sleep duration, leaving 83,511 participants.
Sleep duration was assessed through self-reported responses to questions about average nightly sleep duration over the preceding three months. Baseline sleep duration was categorized into four groups: ≤5 hours, 6 hours, 7 hours (reference), and ≥8 hours. Annual changes in sleep duration were calculated as the relative difference between sleep duration at the last survey and baseline, divided by the time interval. Participants were categorized into three groups based on annual changes: decrease (0 minutes/year).
Potential covariates included demographic variables (age, sex), socioeconomic and lifestyle factors (cigarette smoking, alcohol consumption, tea consumption, body mass index (BMI)), and snoring. Follow-up for cancer incidence was conducted through biennial health examinations, linkage with the Tangshan medical insurance system, and review of medical records. Incident GI cancers were classified according to the International Classification of Diseases, 10th revision.
Statistical analyses included descriptive statistics, chi-square tests, and analysis of variance. Cox proportional-hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for GI cancer incidence according to sleep duration and annual changes in sleep duration. Models were adjusted for age, sex, smoking, alcohol consumption, tea consumption, BMI, and snoring. Sensitivity analyses excluded the first two years of follow-up to address potential reverse causality. Linear trends were assessed by modeling numeric values for sleep duration categories.
Results Baseline characteristics of participants showed significant associations between sleep duration and age, sex, smoking, alcohol consumption, tea consumption, snoring, and BMI. Participants with incident GI cancer were older, more likely to be male, and had higher rates of smoking and snoring compared to those without cancer.
In baseline sleep duration analyses, females with short sleep duration (≤5 hours) had a significantly lower risk of GI cancer (HR: 0.31, 95% CI: 0.10–0.90). A linear relationship between baseline sleep duration and GI cancer risk was observed, particularly in males and those aged over 50 years. Short (6 hours) and long (≥8 hours) sleep durations were associated with an increased risk of pancreatic cancer (HR6 vs. 7h: 2.67, 95% CI: 1.08–6.61; HR≥8 vs. 7h: 3.22, 95% CI: 1.14–9.05). A linear relationship was also observed between sleep duration and colorectal cancer risk.
Annual changes in sleep duration analyses revealed that decreased sleep duration (0 minutes/year) was associated with a higher risk of GI cancer in females (HR: 2.89, 95% CI: 1.14–7.30). Decreased sleep duration was also associated with an increased risk of liver cancer (HR: 1.85, 95% CI: 1.20–2.83). Sensitivity analyses confirmed these findings, with increased sleep duration in females associated with a higher risk of GI cancer (HR: 4.20, 95% CI: 1.52–11.64).
Discussion This study is the first to comprehensively examine the association between baseline sleep duration, annual changes in sleep duration, and the incidence of GI cancers in a large population-based cohort. The findings suggest that both sleep duration and changes in sleep duration are associated with GI cancer risk, with variations by sex and age.
The observed association between short sleep duration and reduced GI cancer risk in females contrasts with previous studies that have reported increased risks with short sleep duration. The linear relationship between baseline sleep duration and GI cancer risk in males and older adults suggests that longer sleep duration may be a risk factor in these groups. The U-shaped association between sleep duration and pancreatic cancer risk, with both short and long sleep durations increasing risk, highlights the complexity of sleep’s role in cancer development.
The association between decreased sleep duration and increased GI cancer risk, particularly in older adults, underscores the potential impact of sleep changes on cancer risk. The increased risk associated with increased sleep duration in females may be related to alterations in appetite-regulating hormones, leading to obesity and subsequent cancer risk. Comorbidities and residual confounding may also play a role in this association.
The study’s strengths include its large sample size, prospective design, and comprehensive assessment of sleep duration and changes over time. The inclusion of multiple covariates and sensitivity analyses enhances the robustness of the findings. However, limitations include the reliance on self-reported sleep duration, lack of information on sleep quality and disorders, and the unbalanced sex distribution of participants.
In conclusion, this study provides evidence that both sleep duration and annual changes in sleep duration are associated with the incidence of GI cancers, with variations by sex and age. Further research with larger sample sizes, longer follow-up, and more detailed sleep assessments is needed to confirm these findings and explore the underlying mechanisms.
doi.org/10.1097/CM9.0000000000001770
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