The influence of BRCA1/BRCA2 mutations on toxicity related to chemotherapy and radiotherapy in early breast cancer patients.

OBJECTIVE: The presence of BRCA gene mutation and low expressions of BRCA proteins are associated with a greater sensitivity of tumor cells to ionizing radiation and to cytostatics damaging the DNA of the cells. The purpose of this study was to estimate the rate of adverse events in BRCA1/2-associated breast cancer patients receiving anthracycline-based chemotherapy compared to patients without mutation. The authors also compared radiotherapy toxicity in these 2 groups.

METHODS: The analysis included 270 early-stage breast cancer patients treated between 2006 and 2012. All patients were examined for the presence of BRCA1/2 mutations.

RESULTS: BRCA mutation was detected in 41 (15%) patients. Toxicity grade 3, especially nausea and vomiting, was observed more often in noncarriers (7 vs. 13%, p = 0.0008). Neutropenia was detected more frequently in patients with BRCA1/2 mutation (32 vs. 10%), but only after 1 cycle of chemotherapy (p = 0.0007). There was increased radiation toxicity in BRCA1/2 patients who underwent mastectomy and neoadjuvant chemotherapy (p = 0.016).

CONCLUSIONS: BRCA1/2 mutation carriers seemed to be more at risk of neutropenia after the first cycle of the treatment. In terms of other side effects, there was a lack of increased toxicity in this group. Mastectomy and neoadjuvant chemotherapy were risk factors for radiation toxicity in mutation carriers.