Clinical Features and Molecular Phenotypes of Breast Cancer in Patients with Type-2 Diabetes Mellitus

Objective: To investigate the clinical features, molecular phenotypes and clinical prognosis of breast cancer patients with type-2 diabetes mellitus, thereby providing a basis for individualized therapy of breast cancer.
Methods: 105 breast cancer patients with type-2 diabetes mellitus (DM) presenting from January 2005 to December 2010 were enrolled in this study. 200 breast cancer non-diabetic patients in the same period were randomly selected as the control group. The clinical data of DM group and control group were retrospectively analyzed. The SPSS12.0 software was used for statistics and survival analysis.
Results: The mean age of the patients in DM group were of 57.2±11.8 years, which was older compared with the control group. The percentage of postmenopausal patients was 71.4% and the ratio of grade II+III was 98.8%, which was higher than the control group. The neoadjuvant chemotherapy response rate of DM group was 67.5%, which was lower than control group. The patients in DM group had later clinical stage and more lymph metastasis. The proportion of advanced breast cancer was 68.57% and the ratio of lymph node metastasis was 66.01%. All the difference was significant (P<0.05). But there was no significant difference in tumor size and molecular phenotype between the diabetic group with breast cancer and the control group. Disease-free survival and overall survival rates of DM group were 80.2% and 84.2%, which were worse than those in the control group. All the difference was significant (P<0.05). After excluding the patients with other causes of death, results of overall survival still showed worse in DM group, but the difference was not statistically significant(P>0.05). Serum insulin at fasting and two hours postprandial were higher than normal value in DM group, but serum insulin levels in the control group changed in the normal range.
Conclusion: There were older patients, with a higher proportion of high pathological grade, more lymph node metastasis, later clinical stages in the diabetic group with breast cancer. Breast cancer patients with type-2 diabetes mellitus were at risk of a poor prognosis. Hyperinsulinemia may be the real cause of poor prognosis in breast cancer patients with type-2 diabetes.