Study of I-125 Brachytherapy Versus Intensity-modulated Radiation Therapy to Treat Inoperable Salivary Gland Cancer

Inclusion Criteria: * Patients are diagnosed histologically as primary or recurrent salivary gland cancers that may occur in either major salivary glands or minor salivary glands. * The inoperable circumstance include: Primary or recurrent salivary gland cancers that could not be resected completely or could not get negative incision. * T3/T4 tumor patients with severe medical comorbidities could not accept the high risk of perioperative complications. * At least one measurable tumor or focus (according to RESIST 1.1 Standard). * Karnofsky score\> 60. * Survival time predicted ≥ 3months; * HGB≥9 g/dL, WBC≥3.0×10\^9/L, NEUT≥1.5×10\^9/L, platelet count (PLT)≥ 100×10\^9/L; TBIL≤1.5 upper limit of normal, Alanine aminotransferase (ALT)/AST≤3 upper limit of normal; Cera≤1.5 upper limit of normal. * Male or female with fertility in the experiment are willing to take contraceptive measures. Exclusion Criteria: * Radioactive therapy history of head and neck. * Suffering from other malignant tumor in recent five years, except skin basal cell carcinoma or carcinoma in situs of cervix. * Chemotherapy history. * Receiving other effective therapy. * Distant metastases. * Pathologic result as squamous cell carcinoma. * Neurological or mental abnormalities which affect cognitive ability. * Severe cardiovascular and cerebrovascular diseases, such as heart failure (NYHA III-IV class), uncontrolled coronary heart disease, cardiomyopathy, uncontrolled arrhythmias, uncontrolled hypertension, myocardial infarction or cerebral infarction within past six months. * Active serious clinical infections :\> Class 2 NCI-Common Toxicity Criteria for Adverse Effects (CTCAE) Version 4.0 within 14 days before randomization, including active tuberculosis. * HIV infection or active hepatitis B or hepatitis C. * Uncontrolled systemic diseases, such as poorly controlled diabetes mellitus. * Medical history of interstitial lung disease, such as interstitial pneumonia, pulmonary fibrosis, or baseline chest X-ray / CT showed evidence of interstitial lung disease; * Pregnancy (via urine β-human chorionic gonadotropin test to determine) or breastfeeding.