Adolescent body mass index and risk of colon and rectal cancer in a cohort of 1.79 million Israeli men and women: A population-based study

BACKGROUND: This study examined the association between the body mass index (BMI) in late adolescence and the risk of colon and rectal cancer. METHODS: This study analyzed a cohort of 1,087,358 Jewish men and 707,212 Jewish women who underwent health examinations at the ages of 16 to 19 years between 1967 and 2002 and were followed by linkage to the national cancer registry up to 2012. Cox regression was used to estimate hazard ratios (HRs) for cancer according to age- and sex-adjusted BMI percentiles from the US Centers for Disease Control and Prevention (overweight, 85th percentile to <95th percentile; obesity, ≥95th percentile). RESULTS: Over a median follow-up of 23 years, 2967 incidence cases of colorectal cancer, including 1977 among men (1403 in the colon and 574 in the rectum) and 990 among women (764 in the colon and 226 in the rectum), were identified. Overweight and obesity were associated with the risk for colon cancer among both men (HR for overweight, 1.53; 95% confidence interval [CI], 1.28-1.84; HR for obesity, 1.54; 95% CI, 1.15-2.06; statistically significant from a BMI of 23.4 kg/m² [spline analysis]) and women (HR for overweight, 1.54; 95% CI, 1.22-1.93; HR for obesity, 1.51; 95% CI, 0.89-2.57; significant from a BMI of 23.6 kg/m²). Obesity, but not overweight, was associated with a risk for rectal cancer among men (HR, 1.71; 95% CI, 1.11-2.65; significant from a BMI of 29.6 kg/m²) and women (HR, 2.03; 95% CI, 0.90-4.58; significant from a BMI of 30.6 kg/m²). CONCLUSIONS: Being overweight or obese in adolescence was associated with an increased risk of subsequent colon cancers in men and women, whereas obesity was associated with rectal cancer. Cancer 2017;123:4022-30.