Obesity is associated with development of clear cell and possibly chromophobe renal cell carcinoma (RCC), but not papillary RCC, researchers concluded.
In a nested case-control study within the Kaiser Permanente Northern California (KPNC) health care network, a team led by Mark P. Purdue, PhD, of the National Cancer Institute in Bethesda, Maryland, found that obesity (a body mass index of 30 kg/m2 or higher) was associated with significant 1.5-fold increased odds of clear cell RCC and non-significant 2.5-fold increased odds of chromophobe RCC. In a meta-analysis that included 3 additional previously published studies, Dr Purdue and his colleagues found that obesity was associated with a significant 1.8- and 2.2-fold increased summary relative risk of clear cell and chromophobe RCC, but was not significantly associated with papillary RCC.
“Our results provide support for the hypothesis that histologic subtypes of RCC represent distinct etiologic pathways, and that obesity is more strongly associated with risk of clear cell RCC,” the authors concluded. “Additional research to elucidate the underlying biology of specific subtypes of RCC is warranted. More generally, our findings underscore the importance of accounting for histologic subtype in investigations of RCC etiology.”
The KPNC study included 685 RCC cases and 4266 controls. Of the RCC cases, 421 were clear cell, 65 were papillary, 24 were chromophobe, and 35 were of other histology. The remaining 141 were not otherwise specified.
Callahan CL, Hofmann JN, Corley DA, et al. Obesity and renal cell carcinoma by histologic subtype: A nested case-control study and meta-analysis. Cancer Epidemiol. 2018;56:31-37.