Study of 1.7 Million Patients Finds Strong Link Between Teenage Obesity, Colon Cancer Risk

Being overweight or obese as a teenager raises the risk of developing colon cancer later in life, a new study in the journal CANCER has found. Being obese was also linked with higher rates of rectal cancer, the study found, at a time when obesity rates are rising along with concerns about the way early weight gain affects health later in life.

Researchers from Rabin Medical Center and Tel Aviv University in Israel examined rcords from more than 1.087 million Jewish men and 700,000 Jewish women, including body mass index (BMI) at 16 to 19 years, between 1967 and 2002. Study participants were followed an average of 23 years, until 2012.

During that time, 2967 new cases of colorectal cancer were diagnosed, including 1977 among men (1403 colon, 574 rectum) and 990 among women (784 colon, 226 rectum). Being overweight or obese were associated with 53% higher risk of colon cancer for men and 54% for women. Obesity was associated with a 71% higher risk of rectal cancer for men, and a 2-fold increased risk for women.

The study is significant in many ways, said lead author Zohar Levi, MD. It is large, with a long follow-up period, and BMI was measured, not recalled. "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,” he said in a statement.

The main limitation, he said, 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 smoking, which might affect risk estimates. Family history of colorectal cancer was also unknown.

Cancer and obesity have been linked for some time; last summer a study in the New England Journal of Medicine added 8 more cancers to a growing list associated with obesity. At the time, the report mentioned colon and rectal cancer and said that being overweight or obese as a teenager carried similar risks as an adult.

CANCER is the journal of the American Cancer Society.

Reference

Levi Z, Kark JD, Katz LH, et al. 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 [published online July 24, 2017]. CANCER. 2017; DOI: 10.1002/cncr.30819