Effect Of Metformin On Prognosis Of Breast Cancer Patients Complicated With Type2Diabetes Mellitus

Background Recent studies have concluded that the incidence of malignant neoplasm such as breast, pancreatic and colorectal cancer in type2diabetes mellitus (DM) patients was dramatically higher than the normal cohort. The relationship between type2DM and breast cancer is much intricate and perplexing. A number of clinical findings proposed type2DM as one of the risk factors for developing breast cancer, and consensus has been reached that type2DM might exert an undesirable influence on the prognosis of breast cancer patients. Besides, convincing evidence has indicated the potential anti-breast cancer efficacy of metformin, which is generally applied as the first-line anti-diabetic agent. Emerging epidemiological surveys have provided hints as to its ability to reduce tumor-associated mortality in type2DM patients.Purpose The present study was designed to explore the clinicopathological characteristics and prognostic status of the breast cancer patients complicated with type2DM, and confer further insight into the effect of metformin on prognosis of breast cancer patients complicated with type2DM, which would provide theoretical rationale for clinical application of metformin in antineoplasm therapy.Methods The study enrolled70breast cancer patients complicated with type2DM.120randomly selected breast cancer cases without type2DM constituted the control group. DM group subjects were further divided into metformin and non-metformin groups depending on whether or not they are on a regular long-term intake of metformin. The clinical information was retrospectively collected and comparison was made between different groups as to the disease-free survival (DFS) and overall survival (OS) of the patients. Survival curves were derived using the Kaplan-Meier method and were compared via the log-rank test. P<0.05was considered statistically significant. For DFS and OS analysis, Cox’s univariate and multivariate methods were performed.Results We observed a predominance of old-aged postmenopausal patients with higher histological grade in the DM group while no significant difference was detected concerning tumor size, lymph node status, ER, PR, Her-2/neu, TNM staging and involvement of adjuvant treatment. Compared with the other two groups, unfavorable prognosis was observed in the non-metformin group as demonstrated by notably shorter DFS and OS. The metformin group exhibited a similar state of survival to that of the control group. By multivariate analysis, histological grade, lymph node metastasis, TNM staging and intake of metformin were proved to be independent risk factors for relapse and metastasis of breast cancer, while lymph node metastasis, complication with type2DM and intake of metformin acted as predictive indicators for OS of breast cancer patients.Conclusions Complication with type2DM brought about a negative impact on OS of breast cancer patients. Intake of metformin was an independent prognostic factor for breast cancer patients complicated with type2DM, which would actually improve long-term survival and reduce the risk of relapse and metastasis. Rational management and early intervention were necessary for such patients.