Background: Neoadjuvant chemoradiotherapy (CRT) followed by surgery is the standard of care for locally advanced rectal cancer. Pathological complete response (pCR) has been associated with decreased local recurrence and improved survival. Means of predicting the pathological response remain incompletely defined.
Materials and Methods: A single-institution prospective analysis of 120 patients with LARC treated with standard neoad- juvant CRT followed by total mesorectal excision. Histological examination of the surgical specimen was performed to as- sess the pathological response, which was categorized as pCR, downstaging or non-responders. Variables were analyzed by uni- and multi-variate analyses to identify any factors that could predict tumor pathological response.
Results: Of total 120 studied patients, only 5% achieved pCR and 73.3% of patients had downstaging. In the multivariate analysis, tumor grade (P = 0.024) and the distance from the anal verge (AV) (P = 0.032) were the only independent predic- tors of response to neoadjuvant CRT. Using logistic regression analysis of different combinations of predictive variables revealed that the combination of tumor grade, the distance from AV and negative nodal status is the strongest model that could predict tumor response to neoadjuvant CRT with accuracy of 90.7%.
Conclusion: High-grade distal tumors without lymph node metastasis could obtain a better response to neoadjuvant CRT.
Pathological response predictors, neoadjuvant chemoradiation, locally advanced rectal carcinoma