Optimal Choice of Radiotherapy in Locally Advanced, Low Rectal Cancer: A Propensity Matched Analysis Comparing...

Area of Science:

• Colorectal surgery
• Radiation oncology
• Oncology

Background:

• Low rectal cancer treatment involves neoadjuvant radiation followed by surgery.
• Short-course radiation therapy (SCRT) and long-course chemoradiation (LCRT) are established treatment modalities.
• Total mesorectal excision (TME) is a key surgical technique, with extended resections employed when necessary.

Purpose of the Study:

• To compare oncological outcomes of SCRT versus LCRT in low rectal cancer patients.
• To evaluate treatment efficacy in a high-volume center with expertise in extended TME.
• To identify potential differences in survival, recurrence, and response rates between SCRT and LCRT.

Main Methods:

• Retrospective, propensity-matched study of low rectal cancer patients (≤5 cm from anal verge).
• Inclusion of patients who received neoadjuvant SCRT (25 Gy/5 fractions) or LCRT (50-50.4 Gy/25-28 fractions) followed by TME.
• Exclusion of patients with metastatic disease or prior pelvic radiation; propensity score matching performed on key clinical variables.

Main Results:

• After matching, 466 LCRT and 157 SCRT patients were analyzed.
• Three-year disease-free survival (DFS) and overall survival (OS) were similar between SCRT and LCRT groups (64% vs. 62% DFS, p=0.8).
• No significant differences observed in local recurrence-free survival, pathological complete response (18% vs. 20%), or CRM positivity (6.4% vs. 10%). Clinical T4 tumors showed significantly lower 2-year DFS with SCRT (41.2% vs. 58.7%, p=0.03).

Conclusions:

• SCRT demonstrates comparable oncological outcomes to LCRT in appropriately selected low rectal cancer patients.
• LCRT may be a more effective option for patients with clinical T4 low rectal tumors, associated with better DFS.
• The choice between SCRT and LCRT should consider tumor stage and patient selection for optimal outcomes.