Application of 125I interstitial brachytherapy in the treatment of local advanced parotid adenoid cystic carcinoma / 中华放射医学与防护杂志

ABSTRACT

Objective:To evaluate the efficacy of 125I interstitial brachytherapy in the treatment of local advanced parotid adenoid cystic carcinoma (ACC), and to analyze prognostic factors affecting treatment outcome, in order to provide references for the treatment of local advanced parotid adenoid cystic carcinoma. Methods:Patients with histology-confirmed ACC of the parotid who received 125I interstitial brachytherapy in Peking University Hospital of Stomatology between Aug 2007 and Jan 2018 were included.Prognostic factors affecting overall survival (OS), progression-free survival (PFS), and local control rate (LCR) were analyzed.Meanwhile, distant metastases as well as acute and long-term radiological toxicities were described. Results:A total of 16 patients (11 females, mean age 55.4 years) of stage cT 4bN 0M 0 who received definitive 125I interstitial brachytherapy were included.The median follow-up period was 41.5 months (8-104 months), and the 1-, 3- and 5-year OS were 86.7%, 72% and 54%, respectively.Five patients suffered from local recurrence, the 1-, 3- and 5-year LCR were 93.7%, 80% and 68.7%, respectively, and the 1-, 3- and 5-year PFS were 74%, 53%, and 18.9%, respectively.Nine cases developed distant metastases.Among them, intracranial and pulmonary metastases took place the most frequently and six patients who had skull base invasion developed multi-organ metastases.An encased carotid artery was an independent prognostic factor for distant metastases (HR=12, P=0.045). Severe radiological toxicities were observed in eight patients (8/16, 50%), including radio-dermatitis, hearing loss, progressive trismus, and eye toxicities. Conclusions:The 5-year LCR in patients treated with definitive 125I interstitial brachytherapy for local advanced ACC of the parotid was 68.7%, and skull base invasion and an encased carotid artery were independent adverse prognostic factors of bad prognosis and multi-organ metastases.