Natural history and treatment sensitivity of alveolar soft part sarcoma: A national multicenter analysis from the French sarcoma group

BACKGROUND: Alveolar soft part sarcoma (ASPS) is an ultra-rare sarcoma with limited chemotherapy sensitivity affecting mostly young patients. Tyrosine kinase inhibitors (TKIs) and immunotherapy are therapeutic advances with promising results in this disease. The aim of this study was to describe the characteristics, management and survival of patients with ASPS in France. PATIENTS AND METHODS: The French NETSARC+ database was screened for all adult patients with ASPS managed in French sarcoma centers between 2010 and 2023. RESULTS: Sixty-four patients from 18 centers were analyzed. The 5-year overall survival (OS) of the entire cohort was 87.3 % (95 % CI, 75.0-93.8 %). Fifty-six percent of patients had localized tumors at diagnosis; all were treated surgically, and 47 % received perioperative radiotherapy. With a median follow-up of 91 months, their 5-year OS was 96.3 % (95 % CI, 76.5-99.5 %). Half of the patients experienced metastatic recurrence with a median metastasis-free survival of 87.9 months (95 % CI, 29.6-NE). In patients with metastases, the first-line systemic treatment yielded an overall response rate of 7 %, 26 %, and 40 % for chemotherapy, TKIs, and immunotherapy, respectively. The 5-year OS after metastasis diagnosis was 67.7 % (95 % CI: 50.5-80.0 %). CONCLUSION: Our cohort reinforces existing data on clinical characteristics and demonstrated prolonged survival in both localized and metastatic stages. Among systemic treatments, immunotherapy achieved the highest response rates. We confirmed that ASPS may follow an indolent course in some cases and highlighted recent advances in its management, driven by standardized local treatments in reference centers and innovative systemic therapies.