Re-irradiation of the pelvis for a genitourinary second malignant neoplasm or a local recurrence after full-dose pelvic radiotherapy for a pelvic cancer: Experience in a high-volume cancer center.

Abstract

494 Background: Re-irradiation (re-RT) with external beam RT following prior pelvic RT has not been reported, given both an absence of guidelines and concerns for toxicity. We sought to characterize bladder and bowel toxicities among patients treated with high-dose palliative re-RT for genitourinary secondary malignant neoplasms (SMN) or local recurrence (LR) following prior RT for pelvic cancer and to assess the response to re-RT with regard to palliation of symptoms. Methods: With IRB approval, the records of 28 consecutive patients with advanced pelvic malignancies given palliative re-RT between 2008-2014 were retrospectively analyzed. Descriptive analyses focused on toxicities and symptom control; responses were evaluated by two independent observers. Results: The cohort contained 27 males and 1 female. Initial cancers included 19 prostate, 4 ureteral, 2 bladder, 2 rectal and 1 penile carcinoma and 1 large cell lymphoma. Median initial RT dose was 63.5 Gy (range, 30-75.6 Gy; 8 unknown). The median time between initial RT and re-RT was 9.5 years (range, 0.2-32 years). At re-RT, there were 16 LRs and 12 SMNs including 14 bladder, 11 prostate, 3 ureteral and 1 penile cancers. Indications for re-RT were most commonly pain and bleeding. Given the severity of symptoms and bulk of disease at the time of re-RT, hypofractionated higher-dose RT was given. Median re-RT dose was 50 Gy (range, 27.5-66 Gy). For patients who received < 60 Gy, the median daily re-RT dose was 250 cGy. Re-RT was well-tolerated; there were no grade 2-4 toxicities. After treatment, 24 patients (92%) had complete resolution of their symptoms. Relief was durable in 67% of patients. Median overall survival was 5.8 months (range, 0.3-38.9 months) and 89% of patients were followed until death. Median follow-up was 5.2 months (range, 0.23-30.2 months). Conclusions: This institutional series suggests that moderate- to high-dose re-RT with median cumulative doses ≥ 100 Gy may achieve successful palliation of pelvic symptoms without undue toxicity in patients previously treated with high-dose RT. These results require validation in a larger prospective cohort.