Clinical and molecular diagnosis of pathologic complete response in rectal cancer

The current standard approach to locally advanced rectal cancer involves pre-operative chemoradiotherapy followed by total mesorectal excision. This practice is supported by several studies that have demonstrated superior local control with this approach. This strategy, leads to a pathologic complete response (pCR) in a substantial proportion of patients treated with neoadjuvant therapy. Furthermore, pCR has been shown to be a reliable predictor of improved oncologic outcomes. This observation has led to an increased interest in the pursuit of identifying clinical, radiographic, pathologic and biochemical predictors of pCR. This review discusses the promising approaches to and most recent advancements in predicting pCR in rectal cancer.