The Relationship Between The Salivary Glands Function And The Dose-volume Effect In Nasopharyngeal Carcinoma Patients With Intensity Modulated Radiation Therapy

Objective: To study the relationship between the salivary glands function and the dose-volume effect on nasopharyngeal carcinoma(NPC)patients with Intensity Modulated Radiation Therapy(IMRT).Method: Between October 2012 and June 2015,24 patients aged 46-68 with nasopharyngeal carcinoma treated with IMRT at our hospital were included in the research.There are 3 patients in stage Ⅰ,7 patients in stage Ⅱ,8 patients in stage Ⅲ,6 in stage Ⅳ_A based-on Fuzhou 1992 Staging System.Patients in stageⅠ and ⅡA were treated with radiotherapy,while stage Ⅱ_B,Ⅲand Ⅳ_A were treated with radiotherapy and chemotherapy.The functional assessment of the salivary glands in 24 NPC patients was examined by MRI diffusion weighted imaging(MRI-DWI)at 1 week before radiotherapy,the 3 months,6 months,9 months after radiotherapy.Results:1 18 of 24 patients’ symptom of dry mouth at the 9 months after radiotherapy were better than that at the end of radiotherapy.2 of 18 patients encountered grade1-0;5 of 18 patients experienced grade2-1;0 of 18 patients had grade2-0;6 of 18 patients experienced grade3-1;5 of 18 patients had grade3-2.6 of 24 patients’ symptom of dry mouth has no difference compared at the 9 months after radiotherapy to at the end of radiotherapy.2 Compare the apparent diffusion coefficient(ADC)(×10-3mm2/s)of salivary glands measured in all 24 patients at the 9 months after radiotherapy :0-1grade symptom of dry mouth were totle 13 patients,these were measured the ADC(1.14±0.21);≥2 symptom of dry mouth were totle 11 patients,these were measured the ADC(1.37±0.19).The result of two groups showed significant difference in anaesthesia.(P=0.014<0.05).3 Analyzed the factors about the symptom of dry mouth,we found that the primary factors were mean dose and V40.The independent hazards were mean dose and V40.We suggested that the dose≤30Gy and volume V40≤30% is for the preservation of salivary glands function.Conclusions:1 It was the 9 months after radiotherapy that can improve the symptom of dry mouth.2 We suggested that the dose≤30Gy and volume V40≤30% is for the preservation of salivary glands function.3 The symptom of dry mouth could be evaluated by MRI-DWI.The salivary ADC evaluates the function of salivary glands and agrees with condition of the symptom of dry mouth.