Clinical Efficacy And Prognostic Analysis Of Postoperative Radiotherapy For Adenoid Cystic Carcinoma Of The Head And Neck Region

objective: The aim of this study was to retrospectively evaluate the results of postoperative radiation therapy(PORT)and to identify prognostic factors predictive of treatment outcomes in patients with adenoid cystic carcinoma of head and neck region(ACCHN).Methods : The ACCHN patients treated by postoperative radiotherapy at Sichuan cancer hospital between January 2005 and January 2015 were retrospectively evaluated.A total of 64 patients were included in the analysis.The median age was 48.5 years old(range,21-73 years old).Thirty-eight(59.4%)patients were male and Twenty-six(40.6%)were female.Tumors were located in major salivary glands(n=29,45.3%)and minor salivary glands(n=35,54.7%).Three(4.7%)patients had stage I,21(32.8%)patients had stage II,11(17.2%)patients had stage III,22(34.4%)patients had stage IVa,and 7(10.9%)patients had stage IVb disease.The number of R0?R1?R2 surgicle resection classification patients were 32(50%)?21(32.8%)?11(17.2%).The median total RT dose was 62 Gy(range,50-72 Gy).A half of patients were treated with definitive chemoradiation therapy(CRT).Statistical analyses were performed using the log-rank test for univariate analysis and the Cox proportional hazard model for multivariate analysis.Results: The median follow-up period was 68.5 months(38-132 months).15 cases(23.4%)had local regional recurrence(LRR),28 cases(43.7%)had distant metastasis(DM),and 13 cases(20.3%)died.The 5-year local-regional reccurence free survival(LRRFS),distant metastasis free survival(DMFS)and overall survival(OS)were 77.8%,52.6% and 86.2%.In univariate analysis,T stage,N stage,UICC classification,surgicle resection classification,bone destruction and perineural invasion(P < 0.05)were the prognostic factors for OS;UICC classification,surgicle resection classification,adjuvant chemotherapy,bone destruction and muscle infiltration(P < 0.05)were the prognostic factors for DMFS;The primary site,T stage,UICC classification,surgicle resection classification,perineural invasion(PNI)and muscle infiltration were the prognostic factors for LRRFS.In R0 stage resection group,T stage,radiation dose and perineural invasion(P<0.05)were the prognostic factors for LRRFS.In multivariate factors analyses,surgicle resection classification was the significant prognosticator for OS(P=0.004)and DMFS(P=0.011),T stage was an independent prognostic factor for OS(P=0.003),adjuvant chemotherapy was an independent prognostic factor for DMFS(P=0.039).perineural invasion(PNI)(P=0.042)and the primary site(P=0.012)were the independent prognostic factor for LRRFS.In R0 resection groop,perineural invasion(PNI)(P=0.012)and radiation dose(P=0.035)are independent prognostic factors of LRRFS.The most common acute toxicities over three degrees were myelosuppression(15.6%),mucositis(7.8%)and skin reactions(7.8%).Conclusion Distant metastasis is the main modes of treatment failure in patients with adenoid cystic carcinoma of head and neck region(ACCHN)after postoperative radiotherapy.The R0 stage surgical resection(negative margin)is an important predictor of good prognosis,and is the main goal of treatment.Chemotherapy can improve the distant metastasis survival rate(DMFS)of ACCHN patients in our center.For patients with R0 surgical resection,who with perineural invasion(PNI)and the late T stage should actively give full amount of postoperative adjuvant radiotherapy(dose of more than 60Gy)to reduce local-regional recurrence;For patients with no lymph node metastasis,lymphatic drainage area should not be included.The main causes of lung metastasis and local regional recurrence were T staging and non R0 resection.Patients receive postoperative adjuvant radiotherapy are less adverse reaction and tolerable.