Type 1 diabetes is associated with increased risk for some cancer types including stomach, liver, pancreas, endometrium, ovary, and kidney cancers, but a decreased risk for prostate and breast cancer, according to recent data published in Diabetologia.
Data suggest that patients with diabetes have a 20% to 25% increased risk for cancer incidence compared with those without diabetes, although most of these findings have been based on individuals with type 2 diabetes. In this study, researchers analyzed the association between increased cancer risk and type 1 diabetes.
Researchers identified 9149 cancer cases in patients with type 1 diabetes from 5 nationwide diabetes registers in Australia (2000 to 2008), Denmark (1995 to 2014), Finland (1972 to 2012), Scotland (1995 to 2012), and Sweden (1987 to 2012). They linked the data to national cancer registries to provide numbers of incident cancers in people with type 1 diabetes and in the general population.
“Persons with type 1 diabetes had a higher incidence of cancer of the liver, pancreas, kidney, endometrium, and ovary and a lower incidence of prostate cancer than those in the general population,” the authors noted. “However, similar to the findings for type 2 diabetes, the HRs (hazard ratios) of cancer were highest during the time of diabetes diagnosis and declined over time.”
There was no significant increase for men with type 1 diabetes in overall cancer risk (HR=1.01; 95% CI, 0.98-1.04), although there was a 7% increase for women (HR=1.07; 95% CI, 1.04-1.10).
The results revealed increased risks for cancers in the stomach (23% for men, 78% for women), liver (2-fold for men, 55% for women), pancreas (53% for men, 25% for women), endometrium (42%), and kidney (30% for men, 47% for women). Researchers also observed a 44% reduced incidence of prostate cancer and 10% reduced incidence of breast cancer among patients with type 1 diabetes.
Cancer incidence was highest shortly after a diabetes diagnosis, according to the data. Cancer incidence was increased within the first year after a type 1 diabetes diagnosis (2.3-fold increased risk for both men and women). The incidence rate declined to the level of the general population after approximately 20 years for men and after 5 years for women.
The authors of the study noted that the increased cancer incidence among patients with type 1 diabetes could be due to the detection of pre-existing cancers shortly after the diabetes diagnosis, when patients are receiving increased medical attention, rather than an association with type 1 diabetes. The increased cancer risk among type 1 and type 2 diabetes may also be due to a common mechanism like elevated blood sugar levels occurring among both groups of patients.
“Our findings do not support changing the policy for cancer screening in persons with type 1 diabetes,” the authors concluded. “Similar recommendations for lifestyle approaches to reduce cancer risk such as weight management, increasing physical activity, and avoiding smoking apply to persons with type 1 diabetes as for the general population.”
They also noted that future research should be conducted to ascertain whether the incidence of cancer among individuals with type 1 diabetes leads to an increased risk for cancer mortality.