Immunohistochemical expression of carcinoembryonic antigen-related cell adhesion molecules 5, CEACAM6, and SLC7A5: Do they aid in predicting the response to neo-adjuvant chemotherapy in locally advanced breast cancer?

Context: Neo-adjuvant chemotherapy (NACT) has become an integral part of multimodality treatment for locally advanced breast cancer (LABC) worldwide. Predictors of therapeutic response to NACT are lacking. Whether carcinoembryonic antigen-related cell adhesion molecules (CEACAMs) like CEACAM5 and CEACAM6 can act as a predictor of response to therapy is unclear. SLC7A5 gene in humans encodes a large neutral amino acid transporter protein, which has an essential role in tumor cell growth and survival. Materials and Methods: Thirty histopathologically proven cases of LABC, being given NACT, were included in the study. Immunohistochemical examination of the tumor sections was performed for CEACAM5, CEACAM6, and SLC7A5. Response to chemotherapy was assessed using "Response Evaluation Criteria in Solid Tumors" (RECIST) 1.1 criteria. A total of three cycles were given at 3 weekly intervals. After 3 weeks of the last cycle of NACT, the patients were taken up for modified radical mastectomy. The specimen was subjected to histopathological examination. The immunohistochemical results were correlated with response to NACT based on RECIST criteria and histopathology. Results: 12/30 (40%) of the patients had objective clinical response of which 4 (13.33%) patients had pathological complete response. The relationship between CEACAM5 and CEACAM6 and response to NACT was found to be statistically significant, P = 0.004 and P = 0.020, respectively. Furthermore, relationship between response to NACT and node-positive tumors with SLC7A5 immunoreactivity was found to be highly significant (P = 0.009). Conclusion: Biomarkers (CEACAM5, CEACAM6, and SLC7A5) showed promise as predictors of poor response to NACT and can help plan an alternative regime in likely nonresponders to prevent the toxicity of chemotherapy and also in tailoring the therapy in a patient with LABC.