Evaluation Of Pathological Response And Its Predictors In Carcinoma Rectum Following Neoadjuvant Chemoradiation.

Background: Neoadjuvant chemoradiation followed by surgery is the standard of care in locally advanced rectal tumors. Better pathologic response after chemoradiation is associated with better outcomes. Pathologic response may depend on various, patient and tumor related factors. The aim of our study was to assess the pathological response using a modified Ryan scoring system and to study various factors which influence the response.

Materials and methods: This is a retrospective study carried out at a tertiary cancer centre in India. Patient details and histopathology reports of rectal cancer patients who took neoadjuvant chemoradiation from January 2016 to December 2018 were analyzed. Demographic details, pathological response assessed by modified Ryans tumor regression grade (TRG) score and various factors which influence the pathological response were studied. Those with TRG score 0 (complete response) and1(near complete response) were grouped together as good responders and those with score 3 (partial response) and 4 (poor or no response) as poor responders. Univariate and multivariate analyses were performed using logistic regression to determine factors which influence pathologic response.

Results: There were a total of 83 patients. Males and females were equally distributed. 43.4%(n=36) of patients had lower rectal tumors,32.5%(n=27) had midrectal tumors and 24.1%(n=20) had upper rectal tumors. 46% of patients were good responders which includes complete responders ,17% (n=14) and those with a near complete response,29% (n=24). 54% of patients were poor responders,which includes those with incomplete response,36% (n=34) and with no or poor response,18% (n=15). Among the upper rectal tumors, only 20% had good response and among the mid and lower rectal tumors 54% had good response.(p value 0.02).63% of males were good responders in comparison to 37% among females (p value 0.05).

Discussion: Response to neoadjuvant chemoradiation with capecitabine in locally advanced rectal tumors in our institute is similar to the literature data with a complete response in 16.9%, near complete response in 28.9% partial response in 36.1% and no response in 18.1% of patients, according to modified Ryan score. It was found that upper rectal tumors had a poorer response when compared to mid and lower tumors and females had a poorer response compared to males.

Conclusion: Even though neoadjuvant chemoradiation remains the standard of care in locally advanced rectal carcinomas, its benefit in upper rectal tumors needs to be validated in larger studies.