Cancer survivors in the United States, especially those diagnosed with breast and colorectal cancers, are more likely to be obese than the general population, suggests a new study. Given that obesity increases risk of many cancers, along with other chronic diseases, the findings are important to better understand and help individuals with a history cancer.
The study was published in the Journal of Clinical Oncology.
For the study, researchers examined data from almost 540,000 adults of the annual National Health Interview Survey, a national representative sample of people who provided data on their weight and other health topics every year. Participant data were grouped into 3-year sets ranging from 1997 to 2014. For each set, which included new people, the study determined obesity rates and separated out those diagnosed and not diagnosed with cancer.
From 1997 to 2014, obesity increased among both those diagnosed and not diagnosed with cancer: it moved up from 22 to 32 percent among cancer survivors and 21 to 30 percent among those not diagnosed. The authors calculated that every year, obesity increased 2.3 percent among those without a history of cancer and 2.9 percent for those who did once have cancer.
Among the cancer survivors, the most common diagnoses were cancers of the breast followed by prostate, and colorectal cancers. When separating out the most common cancers, higher prevalence of obesity was seen more clearly among breast and colorectal survivors compared to non-cancer survivors. Among breast cancer survivors, the estimated increase in obesity every year was 3.1 percent. Obesity among survivors of colorectal cancer was estimated to increase 3.7 percent.
Populations with the highest rates of increasing obesity were colorectal cancer survivors followed by breast cancer survivors. African-American survivors of all three cancers were particularly affected.
In female colorectal cancer survivors, those who are young and non-Hispanic black and had been diagnosed within several years had the highest increasing rates of obesity. Among breast cancer survivors, those who are young, were diagnosed within the past year, and non-Hispanic white had the highest increasing obesity rate. Among men diagnosed with colorectal cancer, the highest increases in obesity were among older men, non-Hispanic blacks, and those at or greater than 10 years from diagnosis.
In this study, obesity was defined as BMI of 30 for non-Asians and of 27.5 for Asians.
Obesity is a cause of both post-menopausal breast and colorectal cancers. The growing population of survivors among these groups may explain some of the findings, the authors note. Data was also self reported, which may have an affect. The National Health and Nutrition Examination Survey, which has experts take measurements, reported a higher obesity prevalence for adults in 2011 to 2012 than this study found, for example.
Findings from this study, and others, do suggest that cancer survivors should discuss weight management needs and options with their physicians, says lead author Heather Greenlee, ND, PhD, associate professor of Epidemiology at Columbia University’s Mailman School of Public Health.
The study was supported by National Cancer Institute.
Source: H. Greenlee, Z. Shi, C. L. Sardo Molmenti, A. Rundle, W. Y. Tsai. Trends in Obesity Prevalence in Adults With a History of Cancer: Results From the US National Health Interview Survey, 1997 to 2014. Journal of Clinical Oncology, 2016.