Reirradiation for rectal cancer and surgical resection after ultra high doses

Local recurrence of rectal cancer following high-dose pelvic radiation presents a difficult management challenge. Conventional wisdom suggests that reirradiation should be avoided and radical pelvic surgery is hazardous after ultra high-dose radiation.

In a unique Phase I/II pilot study, 32 patients with recurrent rectal cancers following previous pelvic radiation underwent planned reirradiation to the pelvis. Initial radiation doses had ranged from 30-64.87 Gy (median dose 45 Gy). Seventeen patients underwent reirradiation followed by radical resection. Fifteen patients were reirradiated for palliative relief of symptoms. Treatment techniques consisted of two lateral fields (7 x 7 to 12 x 10 cm) encompassing the tumor with 2 cm margins. Reirradiation doses ranged from 19.80-47.66 Gy, (median 34.2 Gy). Patients also received concurrent low-dose continuous infusion chemotherapy, (5-FU 200-300 mg/day). Total cumulative radiation doses ranged from 70.6 to 111.6 Gy.

Treatment was well tolerated. Four patients had radiation interrupted/discontinued for diarrhea or leukopenia. Follow-up ranges from 6 months to 36 months. No late sequelae of radiation have been observed to date. Seventeen patients underwent surgical exploration 6-8 weeks following reirradiation. Two patients had extensive disease and were not resected. Fifteen patients underwent radical resection of residual tumor (4 posterior exenterations, 6 APR, 3 transanal abdominal transanal proctocolectomy with coloanal anastomosis (TAATA), and 2 LAR). No patients died postoperatively. No excessive edema, hemorrhage, or adhesions were observed. Two patients developed pelvic abscess and one developed a coloanal stricture. Eleven of 15 resected patients are alive from 6 to 36 months with a 2-year survival of 66%. Of the patients treated palliatively, symptomatic relief was observed in 13/15 patients. No objective complete response was observed, but 6/15 patients had measurable partial response. Median survival in this group was 14 months.

Based on this experience, we believe that in selected patients radical surgical resection after cumulative ultra high doses (70-90 Gy) of radiation can be performed safely. A viable anastomosis is also possible in spite of these high doses. Planned reirradiation for palliative relief of symptoms can be effective without unusual risks of complication. Long-term effects of such ultra high dose radiation and surgery continue to be monitored.