Inflammatory myofibroblastic tumor: A demographic, clinical and therapeutic study of 92 cases.

Purpose: Inflammatory myofibroblastic tumors (IMT) was a rare kind of tumor defined by WHO since 2012. Little was known about this disease. There were controversies about IMT's behavior, predilection site, age distribution, and the best treatment methods. Here we provided a systematic overview on tumor demographical, clinical, biological features as well as treatment efficacy based on real cases from Surveillance, Epidemiology, and End Results (SEER) database.

Methods: 92 patients diagnosed with IMT by histopathology were drawn from SEER database between 2002 and 2014. Patient demographics, clinical features and treatment information were analyzed.

Results: The mean age of onset was 47.4 ± 22.4 years (0 to 83y) and the ages prone to this disease are middle-aged (from 41y to 64y), accounting for 1/3 of all patients. Three peak ages of onsets were 0-4y, 36-40y and more than 50y. 42% of the tumors were located in the soft tissues of limbs, hip, shoulder, head, face and neck. The average tumor sizes were 6.5 ± 5.3cm (1cm to 25cm). Survival in the group of tumor size smaller than 6.5cm was better compared to group of tumor size larger than 6.5cm (P < 0.05). Most of the tumors were malignant or malignant potential (89%), though local and distant metastasis rate were low (5%). Surgery was the most common treatment. However, the survival benefit was still uncertain compared to adjuvant chemotherapy or radiotherapy. Multivariate regression analysis demonstrated that young patients had better survival than old ones.

Conclusions: IMT was a malignant tumor with low risk of local and distant metastasis. The peak ages were 0-4y, 36-40y and more than 50y. The prone sites were the soft tissues of the limbs, hip, shoulder, head, face and neck. Tumor sizes and ages were the factors correlated with survival time.