Evaluation of the pathological response and prognosis following neoadjuvant chemotherapy in molecular subtypes of breast cancer

BACKGROUND The pathological complete response of neoadjuvant chemotherapy for breast cancer correlates with the prognosis for survival. Tumors may have different prognoses according to their molecular subtypes. This study was performed to evaluate the relevance of the pathological response and prognosis following neoadjuvant chemotherapy in the molecular subtypes of breast cancer. METHODS A consecutive series of 88 patients with operable breast cancer treated with neoadjuvant chemotherapy was analyzed. Patients were classified into four molecular subtypes based on the immunohistochemistry profile of the estrogen receptor, progesterone receptor, HER2, and Ki-67. The histological response was assessed according to Miller-Payne grading (MPG) and Residual Disease in Breast and Nodes (RDBN). RESULTS Ten patients (11.4%) achieved a pathological complete response, assessed according to RDBN. The pathological complete response rate was 13.6% according to MPG. Patients with the triple-negative subtype were more likely to achieve a pathological complete response than those with luminal A breast cancer (P=0.03). MPG and RDBN are independent predictors of distant disease-free survival and local recurrence-free survival, but do not predict overall survival. Ki-67, size of invasive carcinoma, lymph nodes, molecular subtypes, MPG, and RDBN are important predictors of distant disease-free survival, local recurrence-free survival, and overall survival. CONCLUSION MPG and RDBN were similarly related to the patient's prognosis. MPG was more suitable for evaluation of distant disease-free survival, and RDBN was more suitable for evaluation of local recurrence-free survival. Survival following neoadjuvant chemotherapy correlated with the pathological reaction rather than the molecular subtype of breast cancer. The molecular subtype of breast cancer was not correlated with pathological response in patients who did not achieve a pathological complete response.