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.

PURPOSE

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.

METHODS AND MATERIALS

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 to 2015.

RESULTS

Median follow-up time was 98 months (range, 1-509 months). 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 23 months (interquartile range, 15-38 months). 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 ≤30 years (hazard ratio [HR], 2.94; P = .005; 95% confidence interval [CI], 1.38-6.27) and large tumor size >10 cm (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 ≤30 years old versus 75% for >30 years old (P < .001). On multivariable analyses, for patients receiving RT alone, the only factor associated with inferior LC was age ≤30 years (HR, 2.87; P = .001; 95% CI, 1.51-5.47). The same was true for patients treated with CMT; age ≤30 years was the only factor associated with inferior LC (HR, 5.36; P = .01; 95% CI, 1.40-20.58).

CONCLUSIONS

Among all patients with desmoid fibromatosis, RT is an effective local therapy for tumor control. However, young patients ≤ 30 years 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.