Type 2 Diabetes Increases Risk of 24 Cancers

The new study, which was conducted by the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) in collaboration with researchers in Sweden and the United States, evaluated data from 125,126 Swedish citizens who had been in the hospital for problems related to Type 2 diabetes. The incidence of cancer among these patients was compared with that of the general population in Sweden. 

The scale of the study also made it possible, for the first time, to quantify correlations between diabetes and less common types of cancer.

Data for the study was gathered from a registry that followed every hospital release in Sweden from 1964 to 2007. These data were combined with the Swedish National Family Cancer Database, which records all cases of cancer in Sweden since 1958. 

The comparison showed that people with Type 2 diabetes have an increased risk of developing 24 different types of cancer among those the epidemiologists explored. The greatest risks were for pancreatic cancer (sixfold increased risk) and liver cell cancer (4.25-fold risk). Cancers that posed more than twice the risk were those that affect the kidneys, thyroid, esophagus, small intestine, and the nervous system.  

A curious finding was that people with Type 2 diabetes have a significantly lower rate of prostate cancer, which was especially obvious in patients who had a family history of the disease. Kari Hemminki of DKFZ commented that "a lower level of male sex hormones in diabetics may be among the factors that are responsible for this."

To rule out the possibility that cancer rates among Type 2 diabetes patients were higher because the cancers were found as a result of hospitalization, the researchers analyzed how many cancers had occurred in the participants after one and five years, respectively, after their hospitalizations. The trend was essentially the same.

The increased risk of cancers among people who have Type 2 diabetes is a significant finding. Given that both Type 2 diabetes and cancer are major health challenges that have a dramatic impact on quality of life and the health care system, this relationship warrants more investigation.

K. Hemminki, X. Li, J. Sundquist, K. Sundquist. Risk of Cancer Following Hospitalization for Type 2 Diabetes. The Oncologist, 2010; DOI: 10.1634/theoncologist.2009-0300