Adolescent obesity linked to colorectal cancer risk in later life

24 Jul 2017 --- Adolescents who are overweight or obese run a higher risk of developing colon cancer and rectal cancer in adulthood than those who have a healthy weight, according to new research published online in CANCER, a peer-reviewed journal of the American Cancer Society. The findings come at a time of growing concern about the impact of adolescent overweight and obesity on chronic disease later in life.

Study results on a potential link between adolescent obesity and the risk of colorectal cancer have so far been conflicting, and many of the studies’ designs have been limited.

Zohar Levi, MD, of the Rabin Medical Center and the Tel Aviv University in Israel, and his colleagues analyzed information on 1,087,358 Jewish males and 707,212 Jewish females who underwent health examinations, including measures of body mass index (BMI), at age 16 to 19 years (predominantly aged 17) between 1967 and 2002. The health status of study participants was tracked until 2012.

Over a median follow-up of 23 years, 2,967 new cases of colorectal cancer were identified, including 1,977 among men (1,403 colon, 574 rectum) and 990 among women (764 colon, 226 rectum).

Overweight and obesity were associated with 53 percent and 54 percent higher risks of colon cancer for men and women respectively. Obesity was associated with a 71 percent increased risk of rectal cancer in men and more than a twofold increased risk in women.

“This is a huge cohort with a minimum follow up of 10 years, and all individuals had measured BMI, not just reported or recalled,” says Professor Levi. “This is the largest study ever, including both men and women, and it had the power to prove the importance of BMI at age 17 on events later in life.”

The main limitation of the study is that the cohort was still young, with the median age at colorectal cancer diagnosis of 49.4 years. The study also lacked data on diet, physical activity and unhealthy habits such as smoking, which might affect risk estimates. Family history of colorectal cancer was also unknown.