Purpose: Desmoid fibromatosis (DF) is a locally aggressive tumor with low mortality but significant morbidity. There is a lack of standard of care, and existing therapies are associated with significant barriers including access, cost, and toxicities. This study aimed to explore the efficacy and safety of the metronomic therapy (MT) in DF in a large, homogenous cohort from India.
Patients and methods: This study involved histologically confirmed DF cases treated with MT comprising vinblastine (6 mg) and methotrexate (15 mg) both once a week, and tamoxifen (40 mg/m2) in two divided doses once daily between 2002 and 2018.
Results: There were 315 patients with a median age of 27 years; the commonest site was extremity (142 of 315; 45.0%). There were 159 (50.1%) male patients. Of the 123 (39.0%) prior treated patients, 119 had surgery. Of 315 patients, 263 (83.5%) received treatment at our institute (MT-151, 77-local treatment, 9-tyrosine kinase inhibitor, and 26 were observed). Among the MT cohort (n = 163, 61.2%), at a median follow-up of 36 (0.5-186) months, the 3-year progression-free and overall survival were 81.1% (95% CI, 74.3 to 88.4) and 99.2% (95% CI, 97.6 to 100), respectively. There were 35% partial responses. Ninety-two patients (56.4%) completed 1-year therapy, which was an independent prognosticator (P < .0001; hazard ratio, 0.177 [95% CI, 0.083 to 0.377]). MT was well tolerated. Predominant grade ≥3 toxicities were febrile neutropenia, 12 (7.4%) without any chemotoxicity-related death. The annual cost of MT was $130 US dollars.
Conclusion: The novel, low-cost MT qualifies as one of the effective, less toxic, sustainable, standard-of-care options for the treatment of DF with global reach and merits wide recognition.