Diabetes affects the risk of developing cancer – increasing it for some forms and reducing it for others, according to the findings of a new European study.
A Danish-led team examined five nationwide diabetes registers in Australia, Denmark, Finland, Scotland, and Sweden to analyse more than 9,000 cancer cases in type 1 diabetes patients.
Although it revealed that across all cancers there was no increased overall cancer risk among men with type 1 diabetes, women had a 7% increased overall cancer risk.
However, the study revealed that women had a 78% increase in stomach cancer, compared to 23% increased risk among men.
There was a two-fold increased risk of stomach cancer among men and a 55% increased risk in women men. For pancreatic cancer, the risk rose by 53% among men and 25% for women), while women had a 47% increased risk of kidney cancer, compared with 30% among men.
Women with type 1 diabetes had 10% reduced risk of having a diagnosis of breast cancer, but the team, led by senior statistician Bendix Carstensen, of the Steno Diabetes Centre, Denmark, Dr Stephanie Read and Professor Sarah Wild, University of Edinburgh, Scotland, say they do not know why this is the case.
There was also a reduced risk of other cancer types, including prostate.
Cancer incidence was highest shortly after diagnosis of diabetes, while it was 2.3 times higher for both men and women during the first year of follow-up compared with longer follow-up.
An increased cancer risk among people with diabetes could be due to a common mechanism such as elevated blood sugar levels, which occur among type 1 and type 2 diabetes patients.
“On average, type 1 diabetes confers an excess incidence of several cancers,” write the authors, whose study is published in Diabetologia.
“In particular, persons with type 1 diabetes had higher incidence of cancer of the liver, pancreas, kidney, endometrium and ovary and a lower incidence of prostate cancer than people in the general population. However, as for type 2 diabetes, increased risk of cancer was highest at the time of diabetes diagnosis and declined over time.”
The authors say they do not recommend changing policy for cancer screening for people with type 1 diabetes.
Carstensen B, Read S et al. Cancer incidence in persons with type 1 diabetes: a five-country study of 9,000 cancers in type 1 diabetic individuals. Diabetologia February 2016. DOI 10.1007/s00125-016-3884-9. [abstract]
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