Locally Advanced Breast Cancer: Response Evaluation to Neoadjuvant Chemotherapy by Clinico-Histopathological Parameters and Molecular Imaging

In India, breast cancer (BC) is not only the commonest cancer but also the commonest cause of cancer mortality among females. Advanced BC constitutes >70% of BC cases at initial presentation in India, among which locally advanced breast cancer (LABC) requires a multi-disciplinary approach with a combination of systemic and locoregional therapies. This descriptive hospital-based study was conducted over 1½ years after seeking approval from the institutional ethics committee. Fifty-five patients satisfying all the criteria of the study were enrolled. The data, thus, collected was pooled into Excel spreadsheet and analyzed using appropriate statistical tools. Most of the patients were postmenopausal, multiparous with breast lump being the commonest symptom. Mean baseline characteristics were age - 48 years, SUV max - 9.2, and Ki-67 - 17.8%. cT4 and cN2 were the commonest pre-NACT tumor and lymph node stage. Invasive ductal carcinoma was the commonest tumor type with the most common tumor grade being grade 3. Hormone receptor positivity and HER2 overexpression were seen in 33 and 17 patients respectively. Post-NACT 32 patients underwent breast-conserving surgery. Pathological complete response (pCR), i.e., ypT0N0, was seen in 13 patients (23.6%). There was slight alteration in hormone receptor status, HER2 expression and Ki-67 in the post-NACT resected tumor. pCR, which is a surrogate marker for improved clinical outcome (DFS and OS) in LABC patients, occurred more commonly in patients with pre-NACT grade 3 tumors, high Ki-67, hormone receptor-negative, and HER2 overexpressing BC (overall, in triple negative BC) but was statistically significant only with Ki-67. Post-NACT, SUV max with a cut off ≤1.5, and ΔSUV max of >80% correlated closely with pCR.