Efficacy and toxicity of rectal cancer reirradiation using IMRT for patients who have received prior pelvic radiation therapy

Purpose: Locally recurrent rectal cancer may cause significant morbidity. Prior reports of rectal cancer reirradiation following local recurrence suggest treatment efficacy, with variable rates of late toxicity. Modern techniques including intensity modulated radiation therapy (IMRT) may improve the therapeutic index. We report outcomes for pelvic reirradiation as treatment for rectal cancer using IMRT. Methods and materials: The records of 31 patients undergoing reirradiation for rectal cancer between 2004 and 2013 were reviewed. All patients underwent IMRT using an accelerated hyperfractionation (39 Gy in 1.5-Gy fractions delivered twice daily, n=15) or once-daily fractionation technique (median dose, 30.4 Gy; range, 27-40 Gy in 15-22 fractions; n = 16). The median cumulative dose was 77 Gy (range, 59-113), and the median interval from prior pelvic radiation therapy was 39.8 months (range, 10.1-307.6). Treatment intent was palliative in 20 patients and neoadjuvant or adjuvant in 11 patients. Surgery was generally reserved for patients with an isolated local recurrence. Concurrent chemotherapy was administered for 25/31 patients, most frequently capecitabine (n=11) or continuous infusion 5-fluorouracil (n=10). Results: Median follow-up was 11.3 months. The prescribed treatment was completed in 29/31 patients (93.5%). Among 18 patients with symptoms attributable to recurrent disease, successful palliation was achieved in 10/18 (55.6%). The rate of grade 2 and grade 3 acute toxicities was 32.3% and 3.2%, respectively. Local control rates at 1 and 2 years were 61.3% and 47.3%, respectively. Median overall survival was 21.9 months, and 1-year survival was 66.7% for patients who had surgical resection versus 58.7% for those who did not (P = .0802). Conclusions: Rectal cancer reirradiation using IMRT is well-tolerated in the setting of prior pelvic radiation therapy. Given significant risk of local progression, further dose escalation may be warranted for patients with life expectancy exceeding 1 year.