The efficacy of iodine-125 permanent brachytherapy versus intensity-modulated radiation for inoperable salivary gland malignancies: study protocol of a randomised controlled trial

Radiation therapy is the method of choice for subjects with inoperable salivary gland malignancies. I-125 brachytherapy, delivering a high radiation dose to a tumor but sparing surrounding normal tissues, is supposed to be ideal modality for the treatment of salivary gland malignancies. We designed a randomised controlled clinical trial to compare the efficacy of I-125 permanent brachytherapy (PBT) versus intensity-modulated radiation therapy (IMRT) for inoperable salivary gland malignancies.

In this study, inclusion criteria are subjects with inoperable salivary gland malignancies, aged 18–80 years, have provided informed consent, with at least one measurable tumor focus, be able to survive ≥3 months, Karnofsky performance status ≥60, have adequate hematopoietic function of bone marrow, have normal liver and kidney function, and are willing to prevent pregnancy.

Exclusion criteria include a history of radiation or chemotherapy, a history of other malignant tumors in the past 5 years, receiving other effective treatments, participating in other clinical trials, with circulatory metastasis, cognitive impairment, severe cardiovascular and cerebrovascular diseases, acute infection, uncontrolled systemic disease, history of interstitial lungdisease, and being pregnant or breast feeding.

The study will be conducted as a clinical, prospective, randomised controlled trial with balanced randomisation (1:1). The planned sample size is 90 subjects. Subjects with inoperable salivary gland malignancies are randomised to receive either I-125 PBT or IMRT, with stratification by tumor size and neck lymph node metastasis. Participants in both groups will be followed up at 2, 4, 6, 9, 12, 15, 18, 21 and 24 months after randomization. The primary outcome is local control rate of the primary site (based on imaging findings and clinical examination, RECIST criteria) in 1 year. Secondary outcomes are progression-free survival, overall survival, quality of life (QOL) measured with the European Organization for Research and Treatment of Cancer QOL Questionnaire (EORTC QLQ-C30 and QLQ-H&N35) of Chinese version, and safety of treatment. Chi-squared test is used to compare the local control rates in both groups. The survival curves are estimated by the Kaplan-Meier method, and log-rank test is used to test the significant difference.

Only few observational studies have investigated the effect of I-125 PBT on inoperable salivary gland malignancies. To our knowledge, this is the first randomised controlled trial to investigate the efficacy of I-125 PBT for subjects with inoperable salivary gland malignancies, and will add to the knowledge base for the treatment of these subjects.

The study is registered to Clinical Trials.gov (NCT02048254) on Jan 29, 2014.