What is your approach following R1 resection in a patient who has received total neoadjuvant therapy for rectal cancer?

This is a challenging scenario and there is not a one-size fits all solution. My decision making would involve thorough assessment of the patient's performance status, co-morbidities, pre-treatment extent of disease, tolerance of therapy, and review of what TNT regimen was employed: number of chemo cycles, long vs short course RT, and surgical pathology/surgeon thoughts regarding localizing the site of recurrence.

Unfortunately, conventional dosing of RT is not particularly effective at controlling rectal cancer post R1 resection. In the Dutch Trial, the patients in the observation arm who underwent R1 resection were recommended post-op CRT to 50.4 Gy, although just under half did. The local recurrence rates were 17% with post-op CRT vs. 16%...