Bottom Line: Obesity was associated with an increased risk of early onset colorectal cancer (CRC) among women younger than 50.
Why The Research Is Interesting: New cases of CRC and death are increasing among people younger than 50 and the reasons for this are largely unknown. This study used data from a large group of women in the Nurses' Health Study II to examine the association of obesity with CRC diagnosed before age 50.
Who and When: 85,256 women ages 25 to 42 who were free of cancer and inflammatory bowel disease when they enrolled in the study and followed up from 1989 through 2011.
What (Study Measures and Outcomes): Current body mass index (BMI), BMI at age 18 and weight gain since age 18 (exposures); relative risk, which is a statistical measure of probability, for new early onset CRC (outcome)
Study Design: This was an observational study. Researchers were not intervening for purposes of the study and cannot totally control for all the natural differences that could explain the study results.
Authors: Yin Cao, M.P.H., Sc.D., of the Washington University School of Medicine, St. Louis, Missouri, and coauthors
Results: There were 114 cases of early onset CRC among the 85,256 women studied. Higher current BMI, BMI at age 18 and weight gain since early adulthood were associated with increased risk of early onset CRC. Obesity, which is a BMI of 30 or above, was associated with highest risk.
Limitations: The study included mainly white women so the findings need to be validated among other races/ethnicities and among men.
Study Conclusions: Obesity and weight gain since early adulthood were associated with increased risk of early onset CRC. This study highlights the importance of weight control throughout life and the potential role of body weight in complementing CRC screening for the early detection of early onset CRC.
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To Learn More: The full study is available on the For The Media website.
(doi:10.1001/jamaoncol.2018.4280)
Editor's Note: The article contains conflict of interest and funding/support disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.
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Journal
JAMA Oncology