Clinicopathological Analysis and Treatment of Adult Patients with Inflammatory Myofibroblastic Tumor: A 15-Year Single-Center Study

PURPOSE: Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal malignancy that occurs primarily in children and adolescents. The clinical and pathological features of IMT in adult patients are not well understood. MATERIALS AND METHODS: We retrospectively searched for records of adult patients with IMT at Fudan University Shanghai Cancer Center from 2006 to 2021. Clinicopathological data, treatments, and outcomes were collected and analyzed. RESULTS: Thirty adult patients with IMT, mostly women (60.0%), were included. The median age of the patients was 38 (21–77). The most common primary site was abdominopelvic region (53.3%), followed by lungs (20.0%). Seven patients had an abdominal epithelioid inflammatory myofibroblast sarcoma (EIMS). The positivity rate of anaplastic lymphoma kinase (ALK) was 81.5% (22/27). Sixteen patients with advanced ALK-positive disease received crizotinib, with an objective response rate (ORR) of 81.3% and a disease control rate of 87.5%. The median progression-free survival was 20.8 months. EIMS was associated with more aggressive behavior; however, the prognosis was similar to that of non-EIMS patients after treatment with an ALK inhibitor. At a median follow-up time of 30 months (95% confidence interval [CI], 13.6 to 46.4), the 5-year overall survival was 77% (95% CI, 66 to 88) in all patients. CONCLUSION: Adult IMTs appeared more aggressive, with a higher incidence of recurrence and metastases, and patients with EIMS had more aggressive cases. Treatment with ALK inhibitors resulted in a high ORR and a durable response, which suggested that ALK inhibitors could be used as a first-line treatment option in adult patients with ALK-positive advanced IMT.