Long-term outcomes and failure patterns of patients with nasopharyngeal carcinoma staged by magnetic resonance imaging in intensity-modulated radiotherapy era: The Zhejiang Cancer Hospital's experience.

PURPOSE

To study and report the clinical outcomes and patterns of failure in the patients with nasopharyngeal carcinoma (NPC) staged by magnetic resonance imaging (MRI) and treated with intensity-modulated radiotherapy (IMRT).

MATERIALS AND METHODS

From January 2007 to December 2011, 720 NPC patients without metastasis staged by MRI were treated with definitive IMRT at Zhejiang Cancer Hospital. The IMRT prescribed dose was 69 Gy to planning target volume (PTV) of gross disease in nasopharynx and 67.5 Gy to PTV of positive lymph nodes in 30 fractions, high risk, and low risk region PTV was 60 and 54 Gy in 30 fractions, respectively. The treatment outcomes and patterns of failure were observed.

RESULTS

Using the 7th edition of the American Joint Committee on Cancer staging system for NPC, the proportions of the 720 patients with Stages I, II, III, and IVa-b disease were 2.1% (15/720), 17.8% (128/720), 51.7% (372/720), and 28.5% (205/720), respectively. After the median follow-up period of 48 months (range: 3-89 months), a total of 146/720 (20.3%) patients had experienced failure: 37 (5.1%) at primary sites, 17 (2.4%) at regional sites, 79 (11.0%) at distant sites, and 13 (1.8%) at multiple sites. The 5-year overall survival, cancer-specific survival, disease-free survival, local relapse-free survival (LRFS), regional relapse-free survival, and distant metastasis (DM) free survival were 86.1%, 88.1%, 76.6%, 90.8%, 93.6%, and 87.2%, respectively. LRFS of T1 to T3 was all >90% and has no significant difference. In addition to N stage, T category, and neoadjuvant chemotherapy were independent predictors for DM in multivariate analysis.

CONCLUSION

Our long-term outcome of large NPC series supports the effectiveness of IMRT for excellent local-regional control though up to 20% patients would develop DM, which becomes the main pattern of failure. T4 disease remained difficult to be cured not only for local recurrence but distant failure. A taxane-based combination chemotherapy might be useful to reduce DM in the induction setting and worth further studying.