1 Introduction
Desmoid tumor (DT), also known as aggressive fibromatosis, is a rare intermediate fibroblastic neoplasm derived from mesenchymal tissues with an annual incidence of approximately 2 to 4 per million per year, and two peaks of age 6-15 years and age 40 years1. Locally infiltrative growth is the nature of DT, and a threat to the vital structure around the tumor. Especially for cranial nerve s (e.g., the facial nerve), critical vessel (e.g., internal carotid artery and internal jugular vein) and organ (e.g., salivary gland and maxillofacial bone) in the head neck (HN) region, which accounts for 7-15% of all the DT, and higher in the pediatric population (26-33%) than the adult (7-9%)2-4, DT would cause severe morbidity.
Observation was advocated as the first treatment for DT by the guideline of National Comprehensive Cancer Network (NCCN)5 and the Desmoid Tumor Working Group 6 under the consideration of the spontaneous regression. However, interventions are unavoidable for the relatively low spontaneous regression rate7,8and potential risk for further adjacent vital tissue destruction and affecting growth by progression.
Complete resection is often the primary intervention for most DT other than those in HN of pediatric patients for the difficulty to get negative margin, and the demand of aesthetic and function9. Chemotherapy, radiotherapy or medical therapy can be performed as supplementary treatment with positive margin after surgery, or sole therapy, in the HN region6,9,10. Among which, the use of radiotherapy is limited in children due to the long-term complication and toxic effects caused by external beam radiation therapy such as secondary cancers and growth retardation of craniofacial bone9,10.
However, brachytherapy, the minimally invasive radiation method with strength of minimizing the growth retardation or second primary cancer in children11, has the potential to offer selection of either supplementary or definitive method for pediatric DT in HN, while long term follow-up outcome is requested.
Therefore, this study attempted to retrospectively evaluate the long-term effectiveness and safety of 125I seed brachytherapy for pediatric DT in HN.