Prognosis Of Nasopharyngeal Carcinoma With Insufficient Radical Dose To The Primary Site

Background: Nasopharyngeal carcinoma(NPC)is sensitive to the radiation.Local control benefits from the intensity-modulated radiation therapy(IMRT)and the combination of the chemotherapy.While,high radiation dose increased the toxicity.It has been reported that in some phase II clinical trials reduced radiation therapy is feasible for children and adolescents with NPC and human papilloma virus-positive(HPV)positive oropharyngeal cancer.However,it is unclear whether reduced-dose radiation for NPC with intensity-modulated radiation therapy(IMRT)can achieve good local control and long-term survival.Therefore,we performed this study in order to explore the prognosis of reduced-dose radiation in NPC.Methods: Between January 2004 and December 2013,57 consecutively histologically diagnosed patients with NPC received less than 66 Gy to the primary site with radiation therapy at our institution.Forty-eight patients who received two-mentioned radiation therapy were also divided into two groups according to whether the radiation dose exceeds 54 Gy.Thirty patients who received less than 54 Gy to the primary site were divided into group A.Eight patients who received ?54Gy to the primary site were divided into group B.Ten patients who received IMRT less than 54 Gy to the primary site were divided into group C.Nine patients who received IMRT more than or equal to 54 Gy to the primary site were divided into group D.We analyzed the 5-year overall survival(OS),locoregional relapse-free survival(LRRFS),progression-free survival(PFS)and distant metastasis-free survival(DMFS).Results: Forty-eight patients received two-mentioned radiotherapy(2DRT).The median follow-up was 27.5(0-148)months.The 5-year overall survival were 36.3% and 57.2% for Group A and B.The difference of the 5-year OS between Group A and B was statistically insignificant(36.3% vs.57.2%,p=0.341).The median follow-up was 75(3-158)months for the whole IMRT cohort.The median age was 56(10-74)years old.Thirteen patients received induction chemotherapy(IC)for two or three cycles.In Group C,the median follow-up was 62 months and the median dose to the primary site was37.9(14.00-51.75)Gy.Six patients died and two patients received re-radiotherapy after recurrence survived.Another two patients were still alive after radiation therapy alone.In group C,the 5-year overall survival(OS)was 50.0%.For group D,two patients who staged as T1N2M0 and T4N3M0 with 8th AJCC had radiotherapy alone.Seven patients received radiotherapy and chemotherapy.The median dose to the primary site was 61.5(57.24-65.40)Gy.The median follow-up was 89 months.Only one patients died because of distant metastasis.The 5-year OS,loco-regional relapse-free survival,progressionfree survival and distant metastasis-free survival were 88.9%,100.0%,88.9% and 88.9%,respectively.Survival analyses showed that group D had significantly better prognosis than group C on OS(88.9% vs.50.0%,p=0.031).For Group B,the 5-year OS was 57.2%,which is obviously worse than Group D's(88.9% vs.57.2%,p=0.02).Conclusions: Patients who received IMRT with more than or equal to 54 Gy but less than 66 Gy with induction chemotherapy achieved better local control and long-term survival.The feasibility and therapeutic effect of reduced-dose IMRT for NPC after IC require further clinical trials to confirm.