Estimation of BCL-2 protein in carcinoma of the breast and its clinical correlation in locally advanced breast cancer

The change in expression of apoptotic markers (Bcl-2 and Bax proteins) brought about by various chemotherapeutic regimens is being used for its predictive value for assessing response to neoadjuvant chemotherapy (NACT) in locally advanced breast carcinoma (LABC).
Aims: (1) Estimation of Bcl 2 expression in LABC, (2) Any change in Bcl 2 expression following chemotherapy in LABC, (3) Any relation of Bcl 2 estimation to changes in size of tumor, nodal status, age, and menopausal status.
Settings and Design: This was a prospective study of 120 cases of LABC.
Materials and Methods: All cases were subjected to biopsy and the tissue was evaluated immunohistochemically for apoptotic marker Bcl-2 family protein. Three cycles of NACT were given at three-weekly intervals. Modified radical mastectomy was performed and the specimens were re-evaluated for any change in the Bcl-2 family protein. The clinical response and immunohistochemical response were correlated and compared.
Statistical Analysis: Coefficient of correlation was calculated by Pearson correlation coefficient (P-value).
Results: Clinical response, as measured by reduction in the tumor size, was observed in 81 (67.5%) patients while immunohistochemical response was observed in 67 (55.8%) patients. Correlation between immunohistochemical and clinical response was found to be statistically significant (P = 0.02). Nodal response was seen in 72 (60%) patients. There were no patients in the N_o group; 22 (53.7%) of the N₁ patients were down-staged to N_o , while 19 (46.3%) remained N₁ . In patients with N₂ disease, 11 (13.9%) were down-staged to N_o status, 39 (49.4%) were down-staged to N₁ status, and 29 (36.7%) did not show any response. Immunohistochemical response was observed in 67 (55.8%) patients. Correlation between immunohistochemical and nodal responses was also found to be statistically significant (P = 0.03).
Conclusions: This significant positive correlation between clinical and immunohistochemical responses highlights the importance of apoptotic marker Bcl-2 family protein in predicting the response of LABC to NACT.