Aims/hypothesis: Cancer-related death is higher among people with vs without diabetes. However, it is not known if this excess risk has changed over time or what types of cancer may be driving these changes.
Methods: To estimate rates of site-specific cancer mortality in adults with vs without self-reported diagnosed diabetes, we used data from adults aged ≥18 years at the time of the interview who participated in the 1985-2012 National Health Interview Survey. Participants' data were linked to the National Death Index by the National Center for Health Statistics to determine vital status and cause of death through to the end of 2015. Cancer deaths were classified according to underlying cause of death. Death rates for five time periods (1988-1994, 1995-1999, 2000-2004, 2005-2009, 2010-2015) were estimated using discrete Poisson regression models adjusted for age, sex and race/ethnicity with p for linear trend reported (ptrend). Site-specific cancer mortality rates were stratified by diabetes status and period, and total cancer mortality rates were additionally stratified by sex, race/ethnicity, education and BMI status.
Results: Among adults with diabetes, age-adjusted cancer mortality rates (per 10,000 person-years) declined 25.5% from 39.1 (95% CI 30.1, 50.8) in 1988-1994 to 29.7 (26.6, 33.1) in 2010-2015, ptrend < 0.001. Among adults without diabetes, rates declined 25.2% from 30.9 (28.6, 33.4) in 1988-1994 to 23.2 (22.1, 24.2) in 2010-2015, ptrend < 0.01. Adults with diabetes remained approximately 30% more likely to die from cancer than people without diabetes, and this excess risk did not improve over time. In adults with diabetes, cancer mortality rates did not decline in some population subgroups (including black people, people with lower levels of education and obese people), and the excess risk increased for obese adults with vs without diabetes. Declines in total cancer mortality rates in adults with diabetes appear to be driven by large relative declines in cancers of the pancreas (55%) and breast (65%), while for lung cancer, declines are modest (7%).
Conclusions/interpretation: Declines in cancer mortality rates were observed in adults with and without diabetes. However, adults with diabetes continue to be more likely to die from cancer than people without diabetes. This study highlights the continued need for greater cancer risk-factor mitigation, especially in adults with diabetes.
Keywords: Cancer; Diabetes; Epidemiology; Mortality; Trends.