Excess risk of stomach, uterine cancer seen in type 1 diabetics

Patients with type 1 diabetes are at higher risk for cancer than the general population, a Swedish study shows. The excess risks are most striking for malignancies of the stomach, cervix and endometrium.

Dr. Weimin Ye, at the Karolinska Institute in Stockholm and colleagues linked data from the Swedish Inpatient Register to the Swedish Cancer Register. They identified records for nearly 30,000 patients presumed to have type 1 diabetes, based on hospitalization for diabetes before age 31. After discounting the first year after hospital discharge, there were 355 incident cases of cancer among the diabetic patients. Relative to the general population, this translated to a standardized incidence ratio (SIR) of 1.2 (i.e., a 20% increased risk), the investigators report in the Journal of the National Cancer Institute for December 3.For stomach cancer, the risk was not elevated until 15 years or more after the index hospitalization, when the SIR jumped to 3.3. Dr. Ye’s group suggests that increased levels of parietal cell antibodies may mediate this vulnerability.The SIR for incident cervical cancer was 1.6, and was similar before and after 15 years’ follow-up. During the first 14 years, diabetics were 4.8 times more likely than the general population to develop endometrial cancer. Thereafter, the risk was still elevated, with an SIR of 2.2. In these women, the threat may be associated with their higher incidence of nulliparity, irregular menstruation and fertility disorders.Risk of cancer of the breast, colon and rectum, pancreas and kidney was unaffected by type 1 diabetes status.Cancer risk is already known to be increased in patients with type 2 diabetes, but risks of specific cancers differ from those associated with type 1 diabetes, the authors point out. For example, pancreatic cancer incidence is higher among type 2 diabetes patients, which supports the theory that hyperinsulinemia is the cause.(Source: J Natl Cancer Inst 2003;95:1797-1800: Reuters Health: December 4, 2003: Oncolink)