Type 2 Diabetes and the Risk of Renal Cell Cancer in Women

OBJECTIVE-Type 2 diabetes is associated with increased risks of several types of cancer; however, its relationship to renal cell cancer remains unclear. RESEARCH DESIGN AND METHODS-A total of 118,177 women aged 30 to 55 years at baseline (1976) were followed up through 2008 in the Nurses' Health Study. Self-reports of physician-diagnosed diabetes were collected at baseline and updated biennially. Hazard ratios (HRs) were calculated using Cox proportional hazards models with adjustment for age, BMI, hypertension, smoking, and parity. RESULTS-During 32 years of follow-up (3,531,170 person-years), 16,819 cases of type 2 diabetes and 330 cases of pathology-confirmed incident renal cell cancer were documented. After multivariate adjustment, type 2 diabetes was significantly associated with an increased risk of renal cell cancer (HR 1.60 [95% CI 1.19-2.17]). These associations were consistent across different strata of BMI, smoking, and hypertension (P(interaction) >= 0.32). The risk of renal cell cancer increased with an increasing number of comorbidities, including obesity, hypertension, and type 2 diabetes (P(trend) < 0.001). When compared with women without any comorbidity, women who had all three conditions had a HR of 4.13 (2.76-6.18) for renal cell cancer. CONCLUSIONS-Type 2 diabetes is independently associated with an increased risk of renal cell cancer in women. In addition, comorbidity of obesity, hypertension, and type 2 diabetes substantially elevates the risk of renal cell cancer.