# Findings in magnetic resonance imaging for restaging locally advanced rectal cancer

## TL;DR

This study shows that MRI restaging after treatment for rectal cancer helps predict outcomes, and short-course radiotherapy with delayed surgery is as effective as long-course therapy.

## Contribution

The study compares two treatment approaches for rectal cancer and highlights the prognostic value of MRI restaging.

## Key findings

- LC-CRT showed better overall survival than SCRT-delay at 5 years.
- MRI response (mrTRG) was a significant predictor of survival outcomes.
- SCRT-delay had similar cancer-specific survival to LC-CRT.

## Abstract

We aimed to assess the prognostic value of restaging magnetic resonance imaging (MRI) in rectal cancer after neoadjuvant therapy and compare long-course chemoradiotherapy (LC-CRT) to short-course radiotherapy with delayed surgery (SCRT-delay).

This retrospective study included 267 patients with locally advanced rectal cancer (LARC) operated on between January 2016 and April 2019, all of whom received either LC-CRT or SCRT-delay in the neoadjuvant setting. The primary outcomes were overall survival (OS) and cancer-specific survival (CSS) based on radiological response assessed using the magnetic resonance tumor regression grade (mrTRG).

In the LC-CRT group, cumulative 1-, 3-, and 5-year OS rates were 94.8%, 86.4%, and 79.0%, while in the SCRT-delay group, they were 83.3%, 68.9%, and 68.9% (P = 0.017). For CSS in the LC-CRT group, cumulative rates were 96.9%, 90.3%, and 85.0%, and in the SCRT-delay group, they were 88.6%, 81.4%, and 81.4% (P = 0.222). There were no significant differences in total histological response rates or local recurrence rates between the treatment groups. The good and moderate response group (mrTRG 1–3) had significantly better cumulative 1-, 3-, and 5-year OS and CSS compared to the poorer response group (mrTRG 4–5) (P = 0.023 for OS and P = 0.048 for CSS).

Unfavorable MRI response is a sign of poor prognosis in LARC. SCRT-delay is comparable to LC-CRT concerning the oncological outcome.