Long-term outcomes of stereotactic ablative brachytherapy for recurrent aggressive fibromatosis: an eight-year retrospective multicenter study

Background Aggressive fibromatosis (AF) was characterized by a high potential of recurrence even following initial definitive treatment. There were considerable controversies regarding the management of recurrent AF. This study aimed to explore the long-term outcomes of iodine-125 (I-125) seed stereotactic ablative brachytherapy (SABT) for recurrent AF. Methods A multicenter retrospective study reviewed 38 recurrent AF patients receiving I-125 seed SABT from July 2013 to July 2021.The clinical outcomes including overall response rate (ORR), disease control rate (DCR), local control time (LCT), overall survival (OS), adverse events (AEs), and symptom relief rate were statistically assessed. Results The ORR and DCR reached 76.3% and 100.0% respectively. The 3-, 5 and 9-year LCT rates were 81.0%, 68.6% and 62.3% respectively. The 3-, 5 and 9-year OS rates reached 94.5%, 84.8% and 60.4% respectively. Multivariate analyses showed that smaller tumor volume and higher dose were significantly positive prognostic factors of LCT (P = 0.034, P = 0.047). Prognostic factors of OS were not found. 20 (52.6%) patients presented with various symptoms at diagnosis, of which 90% (18 patients) achieved complete or partial relief after SABT. The AEs were generally graded ≤ 1 and well-tolerated. Conclusions SABT was an effective and safe alternative treatment for recurrent AF with high safety.