The impact of intensity-modulated radiotherapy in conjunction with chemotherapy on proximal pT3N0 rectal cancer patients after total mesorectum excision.

Background: This study aimed to ascertain if the incorporation of intensity-modulated radiotherapy (IMRT) with chemotherapy (CTx) offered any advantages for patients diagnosed with stage pT3N0 rectal cancer located in the proximal (upper) region following a complete total mesorectum excision (TME).

Methods: We retrospectively examined medical records of stage II/III rectal cancer patients who had undergone CTx or concurrent chemoradiation (CCRT) with IMRT after a successful TME. We juxtaposed a variety of survival outcomes across two patient cohorts. Each outcome was further classified according to Gunderson's risk stratification between proximal and distal (middle and low) rectal cancer patients, and we evaluated the factors associated with each outcome.

Results: The median follow-up duration was 4.9 years. Our research comprised 236 rectal adenocarcinoma patients treated at our institution between 2007 and 2019. They received either the CTx (n = 135) or the CCRT (n = 101) with 10-year locoregional recurrence-free survival (LRRFS) of 90.1% and 96.1%, respectively (p = 0.163). However, after performing multivariate adjustments, a pattern emerged hinting at a better LRRFS for the CCRT group (p = 0.052). Perforation had a strong correlation with locoregional recurrence. No significant differences were observed in other survival between the two treatment arms and their respective subgroups. The CCRT group witnessed significantly higher immediate and chronic complications with p = 0.007 and 0.009, respectively. The CCRT group had two secondary cancer-related fatalities (2%, one attributed to IMRT), and another reported by the CTx group (1%). The sole classified locoregional recurrence within the cohort of 37 individuals treated with CTx for proximal pT3N0 rectal cancer was, in fact, the development of sigmoid colon cancer.

Conclusion: The results suggest that for patients with proximal pT3N0 rectal cancer post-TME, IMRT is better when not combined with CTx, except in highly perilous scenarios or those involving perforation.