"Initial clinical response" to neoadjuvant chemotherapy: an in-vivo chemosensitivity test for efficacy in patients with advanced breast cancer.

Neoadjuvant chemotherapy (NACT) is well established as the standard of care and initial management of choice for patients with advanced breast cancer (ABC). The response is however not uniform. The present study was an endeavor to develop a clinically applicable tool based on the available clinico-pathological data in the routine clinical setting to predict response to chemotherapy in breast cancer in a developing country. From 1st June 2005 to 30th June 2007, 149 patients registered at INMOL hospital with ABC at initial diagnosis having tumor size 5 cm or more and treated with FAC as NACT were prospectively included in the study to analyze association of response after first cycle of chemotherapy (initial clinical response) with that after the third cycle. Tumor measurements were done at base line (before starting chemotherapy), three weeks after the first course of chemotherapy and three weeks after the third course. Percentage change was calculated for the latter two stages. Clinical response was assessed according to WHO/UICC criteria. Pathological complete response (pCR) was based on the histopathology of the operative specimen after NACT. 67.1% patients (cCR 7.4%+cPR 59.7%) responded to chemotherapy while 32.9% (cSD 23.5%+cPD 9.4%) did not. pCR rate was 4%. No patient had initial clinical complete response while 23% had icPR, 74% had icSD and 3% had icPD. All patients with icPR responded to NACT (cCR 29%+cPR 71%) while 60% of icSD responded to chemotherapy (cCR 1%+cPR 59%) and 40% of icSD failed to respond (cSD 31%+cPD 9%). All patients with icPD developed cPD. The high sensitivity of initial clinical response for prediction of cCR and 100% specificity of icPD for prediction of cPD favors its incorporation in clinical practice, as an early predictor of response to NACT in ABC patients.