Title: Complete Response to Neoadjuvant Chemoradiation in Locally Advanced Rectal Cancer: Will DW MRI Hold the Key to Deciding Non Surgical Management?
Authors: Dr Sumod Mathew Koshy MD, FRCR, Dr Anil Prahladan DNB, EDiR, Dr Sonia Abraham MD, Dr Krishnankutty Nair Ramachandran MD
DOI: https://dx.doi.org/10.18535/jmscr/v5i3.28
Abstract
Rectal carcinomas are among the more common malignancies diagnosed worldwide in both genders. Over the last couple of decades, MRI has gradually replaced transrectal ultrasound and CT as the imaging modality of choice in staging of rectal carcinoma. Of late, several studies have been conducted to assess the feasibility of conservative or non surgical management of carcinoma rectum. Patients who show complete pathological response, post chemoradiation may benefit from an organ preserving approach. Multiparametric MR, in addition to its pre eminent role in staging, also plays an important role in the post treatment setting. Our study was designed to assess the ability of DWI in predicting complete pathological response to neoadjuvant chemoradiation in locally advanced carcinoma rectum, to examine the need for MR imaging in the setting of post neoadjuvant chemoradiation and to evaluate the role of DWI in staging of carcinoma rectum. Receiver operating characteristic curves and area under curve (AUC) analysis of multiple variables showed that AUC of ADCmean was higher. Cut off ADC values were also calculated applying Youden’s statistics. Applying the cut off ADCmax of ≤1.53 x 10-3 mm2/s , complete and partial responders were accurately predicted with a sensitivity of 73.33% and specificity of 86.67%. Our study shows that DW imaging if done properly, can predict complete pathological response with reasonably good accuracy thus obviating the need for aPET – CT and also reduce the frequency / or, increase the interval between scopy and biopsy during follow up. Quantitative Diffusion Weighted MR Imaging can potentially provide a single non invasive test to determine complete pathological response and thus decide treatment strategy.
