Cancer among patients with type 2 diabetes mellitus: A population-based cohort study in northeastern Italy.

Diabetes mellitus (DM) is associated with an elevated risk of cancer. The aim of this study was to assess cancer risk and survival in individuals with type 2 DM (T2DM) in Friuli Venezia Giulia, Italy. A retrospective population-based cohort study of 32,247 T2DM patients aged 40-84 years was conducted through a record linkage of local healthcare databases and cancer registry for the period 2002-2009. Standardized incidence ratios (SIRs) with 95% confidence intervals (95%CIs) and 5-year survival probabilities after T2DM and cancer diagnosis were computed. The SIRs for all cancers (n=2069) was 1.28 (95%CI: 1.23-1.34). The highest SIRs were observed for cancers of the liver, female genital organs, small intestine, and pancreas. After 3 years from T2DM diagnosis, a reduced risk of prostate cancer (SIR=0.73, 95%CI: 0.54-0.96) was found in men aged 65-74 years, and a higher risk for breast cancer (SIR=1.24, 95%CI: 1.00-1.52) was found among T2DM female patients. The overall 5-year survival after T2DM was 88.7%. Furthermore, T2DM appeared to have a negative effect on survival of women with breast cancer. This population-based study confirmed that T2DM patients are at increased risk of several cancers, and of premature death in women with breast cancer.