Assessment of predictive markers of response to neoadjuvant chemotherapy in breast cancer

To identify the predictive markers associated with chemotherapy sensitivity, especially those producing pathological complete response (pCR) following neoadjuvant chemotherapy (NACT) in patients with locally advanced breast cancer.

Core needle biopsy of 50 locally advanced breast cancer patients was analysed for histopathology, grade, oestrogen receptor, progesterone receptor, HER2, Ki-67, p53, Bcl-2, and BAX before starting NACT. This was correlated with response to NACT using Response Evaluation Criteria in Solid Tumours criteria.

The mean tumour reduction rate per chemotherapy cycle was significantly higher in BAX-positive (p = 0.01) and Bcl-2-negative (p = 0.04) tumours. BAX expression significantly (p = 0.043) correlated with a response of an at least 30% reduction in tumour size post-NACT on multivariate analysis. A significant relationship was seen between loss of Bcl-2 expression and pCR on univariate (p = 0.048) analysis. Overall, all of the above 12 parameters had 30.4% and 28.5% success in predicting clinical complete response and pCR, respectively, by the Cox and Snell formula.

Of all parameters examined, only the apoptosis-related genes (Bcl-2 and BAX) seemed to exert some influence on the response to NACT, and neither by itself was sufficient to predict pCR; however, 50 patients is not sufficient to simultaneously analyse several predictive markers.