Radiographic imaging of adipose tissue pointed to a risk for malignancies not normally associated with obesity, such as prostate cancer (PCa).

Greater body mass index (BMI) has been shown to be associated with an increased risk for many types of cancer, particularly cancers of the breast, endometrium, esophagus, pancreas, colon and rectum, kidney, thyroid, and gallbladder. BMI, however, does not provide information on the distribution of adipose tissue. Knowledge of cancer risk in relation to specific adipose tissue deposits may be of particular importance in old age, when such tissue tends to be redistributed throughout the body, according to a study group led by Rachel A. Murphy, PhD, a researcher at the National Institute on Aging in Bethesda, Md.

Dr. Murphy and her colleagues examined radiographic measures of adiposity and incident cancer (excluding nonmelanoma skin cancer) in a prospective study of older adults, describing their work in Applied Physiology, Nutrition, and Metabolism. The participants were aged 70-79 years at baseline and were followed for incident cancer for 13 years. None had prevalent cancer (a cancer diagnosis within the previous three years) at study enrollment.

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The final analytical sample included 1,902 individuals (mean age 74 years, 47% male, 57% white) without incident cancer, and 617 with incident cancer, including 268 women (19.2/1,000 person-years) and 349 men (33.1/1,000 person-years). The predominant incident cancers to develop were PCa (126 cases), lung cancer (110 cases), colon and rectal cancers (82 cases), and breast cancer (74 cases). Incident cancers most often developed in men, in current or former smokers, and those who smoked for longer durations.

During a mean and median follow-up of 10.3 years and 12.4 years, respectively, obesity-related cancer developed in 142 women (10.0/1,000 person-years) and 82 men (7.03/1,000 person-years). Total adipose tissue as measured by dual-energy x-ray absorptiometry and visceral adipose tissue as measured by computed tomography were positively associated with cancer risk among women, but were not associated with cancer risk in men.

Total adipose tissue was positively associated with obesity-related cancer risk among women, whereas visceral adipose tissue was positively associated with obesity-related cancer risk among men, even after adjustment for BMI.

Dr. Murphy’s group stated that their results suggests adiposity may carry risk for cancers beyond those identified as obesity-related by the National Cancer Institute and further suggest a possible sex differential with respect to adiposity and cancer risk. Incident cancers among men tended to be nonobesity-related cancers, and women tended to develop obesity-related cancers.