Long-Term Outcomes for Patients With Desmoid Fibromatosis Treated With Radiation Therapy: A 10-Year Update and Re-evaluation of the Role of Radiation Therapy for Younger Patients

Abstract

To update our experience with long-term outcomes in patients with desmoid fibromatosis treated with radiation therapy (RT) and to characterize factors associated with increased risk of local recurrence. We reviewed the records of 209 consecutive patients with desmoid fibromatosis treated with RT, either alone or as combined-modality therapy (CMT) with surgery, at our institution from 1965 to2015. Median follow-up time was 98months (range, 1-509months). The 5- and 10-year local control (LC) was 71% and 69%, respectively. Fifty-nine patients (28%) experienced a local recurrence at a median time of 23months (interquartile range, 15-38months). Among all patients, on multivariable analysis, adjusting for anatomic site, size, age, treatment era (>2005 vs≤2005), treatment approach (RT alone vs CMT), and an interaction between age and treatment, we found only age ≤30years (hazard ratio [HR], 2.94; P=.005; 95% confidence interval [CI], 1.38-6.27) and large tumor size >10cm (HR, 2.51; P=.03; 95% CI, 1.09-5.78) to be correlated with poorer LC. Notably, for patients receiving RT alone, the 5-year LC was 43% for patients ≤30years old versus 75% for >30years old (P<.001). On multivariable analyses, for patients receiving RT alone, the only factor associated with inferior LC was age ≤30years (HR, 2.87; P=.001; 95% CI, 1.51-5.47). The same was true for patients treated with CMT; age ≤30years was the only factor associated with inferior LC (HR, 5.36; P=.01; 95% CI, 1.40-20.58). Among all patients with desmoid fibromatosis, RT is an effective local therapy for tumor control. However, young patients ≤ 30years have notably high rates of local recurrence regardless of treatment strategy, which requires further study. Treatment decisions should be risk-adapted by large referral centers with multidisciplinary expertise in desmoid management.