In this nationwide cohort study, we analyzed data from 10,332,397 participants who underwent 2 consecutive biennial health screenings over a 10-year period. Our findings provide evidence that body weight changes are associated with either an increased or decreased risk for colon cancer, with variations depending on sex and age. In particular, body weight gain in young males < 40 years of age was associated with an increased risk for colon cancer, whereas body weight loss in females > 40 years was associated with a decreased risk.
The association between overweight, obesity, and colon cancer risk factors is well-established17. However, the relationship between body weight changes and colon cancer risk remains unclear. A population-based cohort study involving 139,229 subjects that examined BMI values at three different age points found that a weight gain ≥ 15 kg between 20 and 50 years of age, combined with a higher baseline weight, was significantly associated with an elevated risk for developing colon cancer18. Another population-based case-control study involving 11,887 participants demonstrated a significant positive association between a 5-unit increase in BMI and the risk of colon cancer when BMI was measured 8–10 years before diagnosis19. In this study, we collected data from > 10 million individuals and identified significant factors impacting the relationship between body weight changes and colon cancer risk. We found that males with a BMI range of 18–30 kg/m2, who exhibited body weight gain had an increased risk for colon cancer, while those with a BMI < 18.5 kg/m2, who experienced body weight loss, were associated with a higher risk for colon cancer. Conversely, females with a BMI range of 18–30 kg/m2 who underwent a body weight decrease > 20% exhibited a significant reduction in risk for colon cancer. These findings highlight the complex nature of the association between weight change and the risk for colorectal cancer, emphasizing sex-specific variations. In addition, we found that body weight and elevated BP, FBG, and γ-GTP levels were associated with the risk for colon cancer among males. Furthermore, smoking was linked to colon cancer risk in both males and females, but was particularly remarkable in females. Changing lifestyle habits, including avoiding foods that increase BR and blood glucose levels, and especially quitting smoking among females, could be crucial for reducing the risk for colon cancer.
Forty years of age is a critical period for health because individuals may experience hormonal changes, undergo recommended health screenings, face metabolic shifts, and need to prioritize cardiovascular, bone, and mental well-being. Recently, there has been a global increase in the incidence of early onset colon cancer, affecting individuals < 50 years of age, particularly in high-income countries20. Metabolic syndrome and obesity have been associated with an increased risk for early onset colon cancer21,22. According to a systematic review and meta-analysis, obesity is a significant risk factor for early onset colon cancer23. Moreover, a cohort study in the United States reported that overweight and obese females had a higher risk for incident early onset colon cancer24. The increasing prevalence of obesity among younger individuals is considered to be a major contributor to the rising incidence of early onset colon cancer. In this study, we conducted an analysis focusing on individuals 40 years of age and found that among those < 40 years of age, males who exhibited a weight gain > 20% had a higher risk for colon cancer, while females > 40 years who exhibited a weight decrease > 20% had a decreased risk for colon cancer. These findings indicate that preventing substantial weight gain in males < 40 is crucial for reducing the risk for colon cancer. Additionally, females > 40 years of age could potentially benefit from weight loss to lower the risk for colon cancer. Furthermore, the relationship between body weight changes and colon cancer risk appears to be age dependent, underscoring the importance of adopting sex-specific strategies when addressing the risk for colon cancer.
The strength of our study is supported by the inclusion of a large and diverse population of 10,332,397 participants, which enhanced statistical power and the reliability of our findings, making them more representative of a broader population. Additionally, the longitudinal design of the study provided evidence for following participants over time, offering valuable insights into the relationship between weight change and risk for colon cancer. This approach offers a more comprehensive understanding of how weight fluctuation(s) influence cancer risk across different age groups and extended periods.
However, this study had several limitations. First, body weight changes were broadly categorized into groups (i.e., < 5%, 5–20%, and > 20%) and were only assessed at two time points. While this provided an initial understanding, obtaining more detailed information regarding body weight change patterns and the timing of changes could offer deeper insights into these associations. Second, this study was conducted with a specific population during a particular time frame, which may limit its generalizability to other populations or different time periods. Third, the follow-up period of our study after the second health check-up may not have been sufficient to capture the full impact of weight changes on colon cancer risk, given that the development of colon cancer may take several years. Long-term follow-up data may provide a more comprehensive understanding of this relationship. Fourth, the study did not consider detailed dietary information, which could play a significant role in colon cancer risk and provide additional valuable insights. Further well-designed studies are needed to confirm these findings.