Results of re-irradiation for pelvic recurrence in anorectal cancer patients

Objective: To evaluate outcomes and toxicity profiles after re-irradiation in patients with pelvic recurrence of anorectal cancer. Methods: 25 anorectal cancer patients who received re-irradiation for pelvic recurrence between 2005 and 2015 were included. For initial treatment, all patients underwent surgical resection and preoperative or postoperative radiotherapy. Results: The median follow-up duration was 21.5 months (range, 2.9-84.4). After a median of 43.3 months (range, 11.7-218.5), patients received re-irradiation with a median dose of 45 Gy (range, 36-60). The equivalent dose in 2 Gy fractions (EQD2) of re-irradiation-calculated using α/β = 10 Gy-ranged from 34.5 to 84.0 Gy (median, 46.4). Surgical resection was performed for 11 patients, and 14 patients received concurrent chemotherapy with re-irradiation. The 3-year local progression-free survival was 29.7%. The 3-year overall survival was 49.7%. Concurrent chemotherapy with re-irradiation and re-irradiation doses >50 Gy EQD2α/β =10 were significant prognostic factors for local progression free survival and overall survival according to multivariate analysis. 90% (9 of 10) of patients with symptoms had improvement after re-irradiation. Among 23 patients available for evaluation of late toxicity, 12 developed late toxicities. There were no Grade 4 late toxicities, and 6 patients had Grade 3 late toxicities (small bowel obstruction, bowel perforation and fistula). Conclusion: Re-irradiation for pelvic recurrence of anorectal cancer improved symptoms of patients but the rate of late toxicity was high. Further investigation for patient selection is required. Advances in knowledge: Re-irradiation could be considered as a possible option for pelvic recurrence of anorectal cancer in selected patients.