Predictive factors of complete pathological response in patients with locally advanced rectal cancer.

purposePatients with locally advanced rectal cancer who achieve pathologic complete response (pCR) following neoadjuvant therapy have better long-term outcomes and could be spared from the perioperative and long-term morbidity of rectal resection. The aim of this study was to identify factors that predict the ability to achieve pCR at completion of conventional neoadjuvant therapy, therefore determining their suitability for non-surgical management.

methodsA retrospective analysis was performed on data obtained from a prospectively maintained colorectal neoplasia database. Patients treated for biopsy-proven primary rectal adenocarcinoma between January 1, 2010, and February 28, 2018, who received neoadjuvant radiotherapy or chemoradiotherapy and had undergone surgical resection, were included in this study. Five-year oncologic outcome data was also obtained for 144 patients. Clinicopathological tumour characteristics and treatment regimens were analysed for correlation to clinical outcome.

resultsThree hundred fifty-four patients met inclusion criteria for this study. We identified significant differences between patients achieving a pCR and those that did not for tumour type (adenocarcinoma vs. mucinous/signet ring; p = 0.008), pre-treatment serum CEA level (</≥ 2.5 μg/L; p = 0.003), neoadjuvant therapy type (short-course radiotherapy and long-course chemoradiotherapy; p = 0.008) and preoperative lymph node status (node-negative versus node-positive disease; p = 0.031). Additionally, this is the first report to our knowledge to identify a significant correlation with pCR and the degree of tumour fixity (mobile vs. fixed/tethered; p = 0.038).

conclusionsThis retrospective analysis identified factors that significantly impact a patients' ability to achieve a pCR, which may prove useful for prospectively selecting patients suitable for non-surgical management of disease.