Assessment of pathological response to neoadjuvant chemotherapy in locally advanced breast cancer using the Miller-Payne system and TUNEL

Background: Responses to neoadjuvant (before surgery) chemotherapy in locally advanced breast cancer (LABC) consist of clinical and pathological responses. Evaluating chemotherapy response is essential to predict survival rate and guide future chemotherapy. Until now, the evaluation of pathological response mainly involves quantitative assessment and is often inconsistent with clinical response. We explored the evaluation of pathological responses by both quantitative and qualitative methods, i.e. by evaluating the cellularity of tumour cells and the percentage of apoptosis. Materials and method: A cross-sectional analytical retrospective study was conducted on tissue of LABC diagnosed between 2010 and 2014 at the Department of Anatomical Pathology, Faculty of Medicine, Universitas Indonesia Cipto Mangunkusumo Hospital and Division of Surgical Oncology, Cipto Mangunkusumo Hospital. Biopsy and resection specimens were compared to evaluate reduction in cellularity, which were subsequently categorized into stages of Miller-Payne (MP) classification. The resection specimens were stained with TUNEL and the percentage of apoptosis was calculated. Reduction in cellularity between biopsy and mastectomy specimens with TUNEL staining is evaluated as a modification of the MP method. Results: We found no association between clinical responses with percentage of apoptosis, MP pathological responses and modified MP. There was a correlation between the dead cell evaluated by MP and by modified MP (p=0.000). Conclusion: Modified MP increases the degree or grading of pathological responses, but it does not improve the correlation with clinical response.