O24 Predictive and prognostic roles of polymeric immunoglobuilin receptor in breast cancer

Abstract Introduction Neoadjuvant chemotherapy (NAC) is used with increasing frequency as the primary treatment for breast cancer. Pathological complete response (pCR) which contributes to survival benefit is achieved in only 25–30% of patients with little benefit and significant morbidity in the remainder. Therefore, predicting the patients who are likely to achieve a pCR before commencing NAC is desirable. A pilot study using next generation RNA sequencing of 10 large and locally advanced breast cancer biopsy specimens demonstrated that the expression of polymeric immunoglobulin receptor (PIGR) was significantly increased in breast cancers with pCR. The predictive and prognostic roles of PIGR in breast cancer were expanded in the present study. Method PIGR mRNA expression was determined by RNA in situ hybridization assay in formalin-fixed paraffin-embedded (FFPE) specimens of pre-treatment breast cancer core biopsy from 46 women with breast cancer who received NAC. The expression of PIGR and its associations with pCR and overall survival was examined. Results PIGR mRNA expression was lower in breast cancer compared with normal breast tissue (median H score: 0 vs. 120, P < 0.0001). There was no statistically significant difference in the proportion of pCR in PIGR positive compared with PIGR negative tumours (22.2% vs. 32.1%, P = 0.466). Five-year overall survival of the patients with PIGR positive and negative tumours was 88.9% and 78.3%, respectively. However, overall survival was not significantly different (P = 0.406). Conclusions The expression of PIGR did not appear to be associated with pCR after NAC and did not correlate with overall survival in breast cancer patients. Take-home Message The expression of PIGR did not appear to be associated with pCR after NAC and did not correlate with overall survival in breast cancer patients.