Pre- and Post-diagnosis Diabetes as a Risk Factor for All-Cause and Cancer-Specific Mortality in Breast, Prostate, and Colorectal Cancer Survivors: a Prospective Cohort Study

Abstract

Objective: The relationship between diabetes and all- and cause-specific mortality in individuals with common cancers (breast, colorectal, and prostate) remains both under-researched and poorly understood. Methods: Cancer survivors (N = 37,993) from the National Health Interview Survey with linked data retrieved from the National Death Index served as our study participants. Cox proportional-hazards models were used to assess associations between pre- and post-diabetes and all-cause and cause-specific mortality. Results: Over a median follow-up period of 13 years, 2,350 all-cause, 698 cancer, and 506 CVD deaths occurred. Among all cancer survivors, patients with diabetes had greater risk of: all-cause mortality [hazard ratio (HR) 1.35, 95% CI = 1.27-1.43], cancer-specific mortality (HR: 1.14, 95% CI = 1.03-1.27), CVD mortality (HR: 1.36, 95% CI = 1.18-1.55), diabetes related mortality (HR: 17.18, 95% CI = 11.51-25.64), and kidney disease mortality (HR: 2.51, 95% CI = 1.65-3.82), compared with individuals without diabetes. The risk of all-cause mortality was also higher amongst those with diabetes and specific types of cancer: breast cancer (HR: 1.28, 95% CI = 1.12-1.48), prostate cancer (HR: 1.20, 95% CI = 1.03-1.39), and colorectal cancer (HR: 1.29, 95% CI = 1.10-1.50). Diabetes increased the risk of cancer-specific mortality among colorectal cancer survivors (HR: 1.36, 95% CI = 1.04-1.78) compared to those without diabetes. Diabetes was associated with higher risk of diabetes-related mortality when compared to non-diabetic breast (HR: 9.20, 95% CI = 3.60-23.53), prostate (HR: 18.36, 95% CI = 6.01-56.11), and colorectal cancer survivors (HR: 12.18, 95% CI = 4.17-35.58). Both pre- and post-diagnosis diabetes increased the risk of all-cause mortality among all cancer survivors. Cancer survivors with diabetes had similar risk of all-cause and CVD mortality during the second 5 years of diabetes and above 10 years of diabetes as compared to non-diabetic patients. Conclusions: Diabetes increased the risk of all-cause mortality among breast, prostate, and colorectal cancer survivors, not for pre- or post-diagnosis diabetes. Greater attention on diabetes management is warranted in cancer survivors with diabetes.

Keywords: all-cause; cancer; cardiovascular disease; cohort study; diabetes; mortality.

Figure 1

Analytic sample selection.

Figure 2

Mortality of cancer survivors with diabetes compared to non-diabetic cancer survivors (adjusted for age, sex, race, education level, income level, marital status, body mass index, smoking status, alcohol intake, physical activity, cancer diagnosed age, duration of cancer, history of hypertension, coronary heart disease and stroke, and missing data).