Between 1995 and 1998, the researchers followed 689 women enrolled in the HEAL program who were diagnosed with breast cancer, but who did not have type 2 diabetes. They monitored their health at periodic intervals beginning six months after diagnosis until September 2004 or the patients death. From each patient, they collected a fasting blood sample a common technique for measuring a baseline of insulin or C-peptide levels and information on prognostic, demographic, and lifestyle factors, including weight and height.
In order to determine the relationship between C-peptide levels and prognosis, Irwin and her colleagues statistically adjusted the data they collected for confounding variables such as body mass index, age, race, disease stage and therapy used in treatment. They found that, when arranged into three groups based on C-peptide levels, women in the top third of the group (highest levels) had twice the risk of death compared to women in the bottom third. When looking at just women with invasive breast cancer, the risk of death among women with high C-peptide levels was three times higher than among women with low C-peptide levels. Our findings clearly show that C-peptide and most likely insulin, in and of itself, is a marker for breast cancer prognosis, Irwin said.
According to Irwin, the association was also common in women in their 40s with early stage breast cancer, and less pronounced in women in their 50s or 60s. The higher death rate among younger women suggests that these women may have had more aggressive tumors, possibly related to tumor genetics or family history, said Irwin.
Association of C-peptide concentration with prostate cancer incidence in a prospective cohort. Abstract no. B89:
While studies have consistently shown that men with diabetes are at a decreased risk for prostate c
|Contact: Greg Lester|
American Association for Cancer Research