Type 1 Diabetes and Raised Risk of Certain Cancers
Study suggests, but doesn't prove, that odds increase for some types of tumors, but drop for others
By Steven Reinberg
TUESDAY, March 1, 2016 (HealthDay News) -- Having type 1 diabetes may raise the risk of some cancers, but lower the risk of others, a new study suggests.
A higher risk was seen for cancers of the stomach, liver, pancreas, endometrium, ovary and kidneys. But a reduced risk was seen for prostate and breast cancers, researchers reported.
In type 1 diabetes, the body cannot produce the hormone insulin, which helps regulate blood sugar levels. People with type 1 diabetes must be treated with insulin to survive.
The good news from this study, said researcher Sarah Wild, is that it doesn't seem that insulin treatment is responsible for an increased risk of some cancers, which has been a concern.
"This pattern of cancer risk [seen in the study] is similar to that seen for people with type 2 diabetes and people who are overweight," said Wild, a professor of epidemiology at the University of Edinburgh in the United Kingdom. "This suggests that insulin treatment for type 1 diabetes does not itself increase risk of cancer."
And, Wild pointed out, the new findings only show an association between type 1 diabetes and an increased risk for cancer, not that type 1 diabetes is a direct cause of the increased risk.
Another diabetes expert said it's not clear if there is a cause-and-effect relationship between type 1 diabetes and cancer risk.
"We need to take their [the authors of the new study] findings with caution," said Dr. Joel Zonszein, director of the Clinical Diabetes Center at Montefiore Medical Center in New York City. "Patients with diabetes have enough problems, and they don't need cancer on top of their complications."
He said the lack of a plausible reason why type 1 diabetes might cause an increase in certain cancers makes him suspect that there could be another explanation for the study findings.
It's possible, Zonszein said, that patients in this study were misdiagnosed or misclassified in the national registries used for this study. Some of them may have had type 2 diabetes rather than type 1 diabetes, he suggested. This confusion may have occurred because all the patients the researchers looked at were taking insulin, he said.