A prospective study of proton reirradiation for recurrent and secondary soft tissue sarcoma.

BACKGROUND AND PURPOSE: Proton reirradiation for sarcoma has not been previously described. We hypothesized that this strategy would provide favorable toxicity and survival outcomes.

MATERIAL AND

METHODS

Patients with soft tissue sarcoma in a previously-irradiated field were enrolled on a prospective trial of proton reirradiation. The primary endpoint was provider-reported acute toxicity. Secondary endpoints included late toxicities, local control, and overall survival.

RESULTS

23 patients underwent proton reirradiation. Median time between radiation courses was 40.7months (range 10-272). No grade 4-5 toxicities were observed. One patient (4%) experienced acute grade 3 dysphagia. Common grade 2 acute toxicities were fatigue (26%), anorexia (17%), and urinary incontinence (13%). There were two grade 3 late wound infections (10%) and one grade 3 late wound complication (5%). Grade 2 late complications included lymphedema (10%), fracture (5%), and fibrosis (5%). At a median follow-up of 36months, the 3-year cumulative incidence of local failure was 41% (95% CI [20-63%]). Median overall survival and progression-free survival were 44 and 29months, respectively. In extremity patients, amputation was spared in 7/10 (70%).

CONCLUSIONS

Proton reirradiation of recurrent/secondary soft tissue sarcomas is well tolerated. While longer follow-up is needed, early survival outcomes in this high-risk population are encouraging.