Prediagnosis obesity as measured by body mass index was a risk factor for overall and individual secondary primary cancers in a study of male cancer survivors.
Prediagnosis obesity as measured by body mass index (BMI) was a risk factor for overall and individual secondary primary cancers (SPCs) in a study of male cancer survivors.
Researchers led by Eun-Sook Lee, MD, PhD, of the National Research Institute, National Cancer Center, Korea, found a positive linear trend between prediagnosis BMI and risk for SPCs among Korean male cancer survivors.
“These findings suggest that increased risk of cancer among cancer survivors might be partially due to an increased prevalence of obesity or an increased susceptibility to obesity-related carcinogenesis among cancer survivors compared with the general population,” wrote Lee and colleagues, in a study published in the Journal of Clinical Oncology.
The study consisted of 239,615 male survivors between January 2003 and December 2010. The researchers looked at occurrences of SPCs until December 2011. During those 1,614,583 person-years of follow-up, 4,799 patients were diagnosed with an SPC.
Lee and colleagues found that the age-standardized incidence rate of cancer in the cancer survivors was 1.1 times greater than that of the general population (353.8 vs 321.9 occurrences per 100,000 person-years; P < .001).
In an analysis stratified by BMI, the authors found that in men with a BMI of at least 25 kg/m2, the age-standardized cancer incidence rate for SPCs was 23% higher than for the first primary cancer (391.9 vs 318.3 occurrences per 100,000 person-years). And the increased age-standardized incidence rate of obesity-related cancers was more prominent for SPCs than for the first primary cancer (105.1 vs 81.4 occurrences per 100,000 person-years) among the obese population (P < .001).
Positive linear trends were identified between prediagnosis BMI and all-combined cancers (adjusted hazard ratio [aHR], 1.22), as well as colorectal (aHR, 1.35), lymphoma (aHR, 1.89), biliary tract (aHR, 1.58), kidney (aHR, 2.23), and obesity-related (aHR, 1.28) SPCs. Overall, patients with severe obesity, defined as a BMI of 30 or greater, were 42% more likely to develop an SPC for all-combined cancers.
“When we performed a sensitivity analysis after excluding SPCs within 1 to 2 years after diagnosis of the first cancer, the association between SPC risk and prediagnosis BMI was generally similar to that from the primary analysis,” the researchers wrote.