| Background and Objective: The relationship of biological characteristics of nasopharyngeal carcinoma (NPC) and its potential of cervical lymph node metastases has been recognized. The lymph node-negative (N0) NPC, therefore, may represents a subgroup of this malignancy with unique biologic and clinical features. The treatment results and failure patterns of N0 stage NPC have not been well described in the literature. This analysis was to evaluate the outcomes of patients with N0 NPC treated primarily by external beam irradiation, and to explore for the failure patterns and possible ways to improve the current treatment results.Methods: Retrospective analysis was conducted in 610 patients with N0 NPC who received radiotherapy in our hospital from May 1989 to October 2009. The distribution of whole group of patients, according to the Fuzhou92 staging system, was as follows: T1, n = 57; T2, n = 272; T3, n = 126; T4, n = 155. Computed tomography (CT) scans of the primary lesion were performed to all of the patients. Definitive radiotherapy was delivered to the primary, and prophylatic irradiation to the upper neck and regions that may harbor subclinical disease with 60Co or 6-MV X rays using conventional fraction at 2 Gy daily, 5 fractions per week. Most patients were treated with two large lateral opposing faciocervical fields that covered the primary tumor and the upper neck lymph drainage region to a total dose of 36 to 40 Gy, and then lateral preauricular fields with matching anterior cervical field (including levelsâ…¡,â…¢, and VA) were employed. 68 patients received prophylactic irradiation to the whole neck, or the upper neck combined with one side of lower neck. The total dose to the primary disease delivered by external-beam radiotherapy (EBRT) was 34-91 Gy (median, 70 Gy). The dose to the upper neck and regions that may harbor subclinical disease was 34-70 Gy (median, 50 Gy). Chemotherapy was administered to 65 patients. After the completion of 70-72 Gy of EBRT, 99 patients had nasopharyngeal residual disease, and a boost radiation was employed. The median follow-up time was 65.0 months (range, 3-254 months). The accumulated survival was calculated by the Kaplan-Meier method. Log-rank test was used to compare the survival difference. Cox proportional hazards model was used for multivariate analysis.Results: The 5-year and 10-year actuarial overall survival, disease-free survival, disease-specific survival, local failure-free survival, regional failure-free survival, locoregional failure-free survival, and distant metastasis-free survival rates were 78.7% and 66.8%, 68.8% and 55.8%, 79.9% and 70.4%, 81.2% and 72.5%, 95.8% and 91.8%, 78.3% and 68.5%, 88.5% and 85.5%, respectively. Thirty-one (5.1%) of the 610 patients experienced regional recurrence. Among them, 15 patients (2.5%) had regional recurrence as a first event of failure. Of these regional recurrences, 16 (51.6%) occurred within the irradiation level, while 13 (41.9%) out of the irradiation level, and 2 (6.5%) both in and out of the irradiation level. Totally 192 patients who received radical radiotherapy or chemoradiotherapy failed in locoregional recurrence and/or distant metastasis. Among them, 52.1% of patients presented local recurrence and 27.1% of patients developed distant metastasis as first failure event after treatment. Multivariate analysis showed that T stage was the only independent prognostic factor for patients with N0 NPC (P = 0.000). Late T stage (P = 0.000), male (P = 0.039) and anemia (P = 0.007) were independently the unfavorable factors predicting disease-free survival.Conclusion: Satisfactory treatment outcomes have been achieved in patients with N0 NPC. Local recurrence represents the predominant mode of treatment failure. T stage was the only independent prognostic factor for overall survival. Late T stage, male and anemia were independently the unfavorable factors predicting disease-free survival. It is hoped that an even better survival outcome can be achieved by improving the local control. |
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