Endocrine Abstracts

Background: Observational studies indicate that breast cancer survivors more often are diagnosed with type 2 diabetes mellitus (T2DM) up to several years after treatment completion. As the population of breast cancer survivors increase due to improved diagnostic and treatment methods the importance of understanding possible long-term side effects of the treatment such as T2DM becomes more central. It is reported that women receiving adjuvant chemotherapy experience weight gain and altered body composition with loss of muscle mass and increasing fat mass. Furthermore, studies have shown elevated fasting insulin levels in breast cancer patients before and after treatment. Obesity can lead to insulin resistance and thereby a risk of developing T2DM. It is relevant to consider if changes in glucose and insulin metabolism are seen in relation to breast cancer treatment to further explore the risk of T2DM.

Aim: to examine if adjuvant chemotherapy negatively affects glucose metabolism, outlined by changes in glucose and HbA1c.

Method: Women with early breast cancer stages I-III eligible for chemotherapy were prospectively recruited by Department of Oncology at Rigshospitalet, Denmark. Exclusion criteria were prior malignancy or endocrine disease. Blood samples were drawn immediately before initiation of chemotherapy and after completed chemotherapy. Furthermore, in a subgroup of women an oral glucose tolerance test (OGTT) was performed after completed chemotherapy. Patients drank a concentrated glucose solution and blood samples were drawn at times 0 min, 30 min, 45 min, 60 min, 90 min, and 120 min.

Results: 103 women with early breast cancer were include in the study. 79 patients completed examinations before and after chemotherapy. All women underwent breast surgery and chemotherapy regimens including at least one of the following drugs docetaxel, paclitaxel, epirubicin, and cyclophosphamide. High-dose prednisolone was given as antiemetics. Statistical analysis showed no significant difference in HbA1c before and after chemotherapy with mean values 37.1 mmol/mol and 36.7 mmol/mol respectively and P=0.28. The OGTT was performed in 11 of the breast cancer patients after completed chemotherapy. Furthermore, 7 healthy controls completed an OGTT. Glucose levels at 120 min did not significantly differ between patients and controls with P=0.44 and mean glucose for patients 6.9 mmol/l and controls 6.2 mmol/l.

Conclusion: HbA1c is not significantly altered by chemotherapy in early breast cancer patients. In addition, we find no significant difference in response to a glucose load between a subgroup of patients and controls.