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.