Relationship Between Lymph Node And Distant Metastasis After Intensity-modulated Radiotherapy In Patients With Nasopharyngeal Cacinorma

BACKGROUD & OBJECTIVE: About 80% of patients with nasopharyngeal carcinoma all over the world were in Guangdong,Guangxi,Fujian,Hunan and Jiangxi provinces in southern China,which was the most common in the pearl river delta.Because of its special anatomy,the first choice of treatment for nasopharyngeal carcinoma is radiotherapy,while the combination with chemotherapy is for the local advanced patients.With the popularity of magnetic resonance(MRI)technology and the advance of intensity-modulated radiotherapy(IMRT),the level of comprehensive treatment of nasopharyngeal carcinoma(NPC)improves obviously in recent 10 years,which the total five-year overall survival rate,relapse-free survival rate,and distant metastasis-free survival rate achieve 80%,but the leading cause of death in these patients is still distant metastasis and local recurrence,and distant metastases is still the first of patterns of failure after intensity-modulated radiotherapy for nasopharyngeal carcinoma.About 20% of the patients with NPC after IMRT meet with distant metastasis in five years.A variety of factors lead to the distant metastasis of NPC,especially the lymph nodes.But what are the exact factors of lymph node occurring the distant metastasis,everyone holds a different opinion,there is still not unified conclusion.Therefore,it is urgent to find the lymph node factors related to the distant metastasis of NPC closely.The purpose of this paper is to analyze the characteristics of cervical lymph node of the NPC patients who suffering IMRT,and screened out independent prognostic significance of factors closely associating with distant metastasis,which in order to make reasonable treatment scheme,assess the risk of distant metastasis and evaluate prognosis,strive to reduce the distant metastasis rate,and improve the surial in patients with NPC ultimately.Methods: A retrospective analysis was performed on the clinical data of 458 patients who were newly biopsy-proven and without distant metastatic NPC from January 2010 to February 2012 in our hospital,IMRT was the primary treatment for all the patients.The chi-square test was used to compare of rates between multiple groups,and all survival rates were calculated by the Kaplan-Meier method and analyzed by the log-rank test.The Cox regression model was informed for multivariate analyses.Analyze reasonably the characteristics of cervical lymph node of the NPC patients referencing the standard of lymph node-positive,residual lymph node and distant metastasis.Results: 387 of 458 NPC patients with cervical lymph nodes metastasis,of which 118 patients had a residual mass in the neck after IMRT,were collected and studied.These 387 patients' cervical lymph nodes stay in different levels,17 in ?b,141 in?a,297 in ?b,138 in ?,30 in ?,6 in ?b,24 in ?a,6 in ?b,5 in ?c,229 in ?a,and there is no lymph nodes in the level of ?a,?,?b,?,?,?a,?b.In all cervical positive lymph nodes,the maximum diameter of the maximum cross-section was measured(multiple fused nodes were difficult to be differentiated by individual calculation),and the median diameter of the group was 2.98cm(0.62cm-11.37cm).9 of 387 patients had been suffering jumping metastatic.The total of 118 patients leaving cervical lymph node occur in the primary metastatic lymph nodes.The median diameter of the residual lymph nodes was 0.96cm(0.58cm-2.64cm).Distant metastasis was found in 79 patients(17.25%).The five-year OS,DFS and LRFS were 82.09%,80.34% and 90.39% respectively,and the one-year,three-year,five-year DMFS were 95.85%,89.95% and 82.75% respectively.In univariate and multivariate analysis,the radiotherapy and chemotherapy,the metastatic nodes levels such as ?,?b and ?c,the greatest diameter of lymph nodes,the diameter of residual lymph nodes,the time of lymph nodes completely response were the independent prognostic factors for DMFS(P<0.05).Conclusions: The combination treatment of radiotherapy and chemotherapy could reduce the distant metastasis rate of NPC after IMRT.Larger the lymph nodes were in the neck,the more likely they were to remain,the larger that residual cervical lymph nodes were,and higher risks of distant metastasis there were.It was adverse for the NPC patients with large cervical lymph nodes(especially?6cm),lymph nodes remaining>1cm in diameter,and the residual cervical lymph nodes who did not subside in 3 months after IMRT,which drives us to explore a more reasonable intervention treatment.