Diabetes Y Cancer Renal

Epidemiology/Health Services Research
O R I G I N A L A R T I C L E

Type 2 Diabetes and the Risk of Renal Cell Cancer in Women
HEE-KYUNG JOH, MD, MPH1,2,3 WALTER C. WILLETT, MD, DRPH1,4,5 EUNYOUNG CHO, SCD1,5
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—Atotal 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 (Pinteraction $ 0.32). Therisk of renal cell cancer increased with an increasing number of comorbidities, including obesity, hypertension, and type 2 diabetes (Ptrend , 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. Inaddition, comorbidity of obesity, hypertension, and type 2 diabetes substantially elevates the risk of renal cell cancer. Diabetes Care 34:1552–1556, 2011

most established risk factors for renal cell cancer (4,8,9), and both factors are linked to type 2 diabetes through insulin resistance and metabolic syndrome. Therefore, we hypothesized that type 2 diabetes would be associated with anincreased risk of renal cell cancer and interact synergistically with obesity and/ or hypertension due to the common underlying mechanism of insulin resistance. Defining this association is important given the rising global epidemic of type 2 diabetes and also, to some extent, renal cell cancer, but evidence from previous studies has been unclear. Most investigations were case-control studies (8,10,11)although a few were prospective (9,12,13). In this study, we prospectively evaluated the association between type 2 diabetes and subsequent renal cell cancer risk in the Nurses’ Health Study. RESEARCH DESIGN AND METHODS Study population The Nurses’ Health Study cohort was established in 1976 when 121,700 female registered nurses aged 30 to 55 years returned a mailed questionnaire about medicalhistory and various risk factors for chronic disease. Follow-up questionnaires were sent every 2 years to update information on lifestyle factors and newly diagnosed diseases. Deaths in the cohort were identified by reports from family members in response to the follow-up questionnaires and from the National Death Index. In this study, women who reported renal cell cancer or any other cancer (except fornonmelanoma skin cancer) before baseline were excluded from analyses. The follow-up rate in this study population was 98%. The Nurses’ Health Study was approved by the institutional review board of Brigham and Women’s Hospital (Boston, MA). Assessment of diabetes On the baseline and subsequent biennial questionnaires, we asked the participants if and when they had ever been diagnosed withdiabetes by a physician. All women who reported a diagnosis were mailed a supplementary questionnaire requesting additional information on symptoms,
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he prevalence of type 2 diabetes is increasing worldwide. From 1980 through 2007, the number of Americans with diabetes more than tripled from 5.6 million to 17.4 million (1). Recent epidemiologic evidence suggests that...