Incompletely resected rectum, recto-sigmoid, or sigmoid carcinoma: results of postoperative radiotherapy and prognostic factors.

Postoperative radiotherapy was given in 40 patients with gross or microscopic pathologically proven residual disease after surgical resection of rectum, recto-sigmoid, or sigmoid carcinoma. The radiotherapy target volume included the pelvis with (9 patients) or without (31 patients) the perineum. Median total dose of radiation was 50 Gy (range 30-60). One patient received 30 Gy, 10 received greater than 30 to 40 Gy, 13 received greater than 40 to 50 Gy, and 16 patients received greater than 50 to 60 Gy. The median follow-up in the survivors (16 patients) was 53 months (range: 16-85). Probability of survival with censoring for death due to intercurrent disease was 36% at 5 years. Survival for patients with microscopic residual disease (21 patients) was 40% at 5 years compared to 12% for those with gross residual disease (19 patients) (p = 0.09). Twenty-five patients relapsed. All but one relapse occurred earlier than 50 months after radiotherapy. Approximately half (12/25) of the relapses were observed within 6 months after radiotherapy. Local relapse inside the radiotherapy portals was observed in 9/40 (22%) patients. Therapy-related urogenital complications occurred in no patient and gastro-intestinal complications in three patients (7%). In one patient they were scored WHO grade 4 and in two patients WHO grade 3. Prognostic factors were analyzed using the Cox proportional hazards model. For survival differentiation, grade (p less than 0.001), stage (p = 0.04), and perineal irradiation (p = 0.03) were independent prognostic factors. With relapse-free survival as the endpoint, only stage (p = 0.003) was a statistically significant prognostic factor. There was a trend toward a better relapse-free survival when the perineum was included in the radiation portals (p = 0.09).