Research of Radiotherapy Dose on Suspicious Positive Lymph Nodes in Neck Negative Nasopharygneal Carcinoma Patients

Objective To investigate the regression of lymph nodes, local recurrence, adverse effects and prognosis in neck negative nasopharygneal carcinoma(NPC) patients with uspicious positive lymph nodes (0.5 cm≤maximum diameter＜1 cm，intact capsule,no central necrosis) treated by 64Gy radiation doses. Methods From Jan 2008 to Jan 2011,80 NPC patients with N0 stage who had suspicious positive lymph nodes were studied retrospectively. According to the 2008 staging system, there were 4 patients in stage T1,15 in stage T2,36 in stage T3 and 25 patients in stage T4.All patients were irradiated by IMRT technique. Patients in T1 and T2 were treated by IMRT alone while patients in T3 and T4 by concurrent chemotherapy. The prescription does was(70-74)Gy/30f to the nasopharynx gross tumor volume (GTVnx),64Gy/30f to suspicious positive neck lymph nodes(GTVndsuspicious positive),(60-64)Gy/30f to the first clinical target volume(CTV1) and (50-54)Gy/30f to the second clinical target volume (CTV2).The irradiation time was 6 weeks. Paired T test was used to compare the regression of lymph nodes before and after radiation. Results The follow-up rate was 98.8%. 80 patients had 129 lymph nodes. 117 lymph nodes was CR，6 was PR and NC was 6.Partial response rate was 95.3%.The regression of lymph nodes had statistical differences (P＜0.05) between before and after radiation.The 4-year local-regional control rates, distant metastasis-free survival rate and overall survival rate were 94.6%，95.9% and 93.7%. 4 patients had recurrent events in GTVnx and 3 patients had distant metastasis. The neck skin reaction with grade 1 and 2 was 77.5% and 22.5% respectively. Neck skin radiation fibrosis with grade 1 was 15%. Conclusion The 64Gy radiation dose was the appropriate control dose on suspicious positive lymph nodes in neck negative nasopharygneal carcinoma patients with a acceptable adverse effect.