10-Year Results of Therapeutic Ratio by Intensity-Modulated Radiotherapy Versus Two-Dimensional Radiotherapy in Patients with Nasopharyngeal Carcinoma.

Background: The purpose of this study was to verify 10-year results of survival and late toxicities and assess the ultimate therapeutic ratio of intensity-modulated radiotherapy (IMRT) versus two-dimensional radiotherapy (2DRT) in patients with nasopharyngeal carcinoma (NPC).

Materials And Methods: We retrospectively reviewed the data from 1,276 patients with nonmetastatic NPC who received IMRT or 2DRT from January 2003 to December 2006.

Results: Of the 1,276 patients, 512 were treated with IMRT and 764 with 2DRT. Median follow-up was 115 months. At 10 years, the IMRT group demonstrated significantly better results than the 2DRT group in local failure-free survival (L-FFS; 90% vs. 84%; hazard ratio [HR], 0.57, 95% confidence interval [CI], 0.40-0.81;  = .001), failure-free survival (FFS; 69% vs. 58%; HR, 0.69, 95% CI, 0.57-0.83;  < .001), and overall survival (OS; 75% vs. 63%; HR, 0.62, 95% CI, 0.51-0.77;  < .001). Subgroup multivariate analyses showed that radiotherapeutic technique (IMRT vs. 2DRT) remained an independent prognostic factor for L-FFS in the T1 subgroup (HR, 0.30; 95% CI, 0.11-0.80;  = .02); for FFS in the stage II subgroup (HR, 0.42; 95% CI, 0.24-0.73;  = .002); and for OS in the stage I (HR, 0.20; 95% CI, 0.04-0.96;  = .04), stage II (HR, 0.39; 95% CI, 0.21-0.75;  = .004), and stage IVA-B (HR, 0.74, 95% CI, 0.56-0.98;  = .04) subgroups. The incidence of grade 3-4 temporal lobe necrosis, cranial neuropathy, eye damage, ear damage, neck soft tissue damage, trismus, and dry mouth was significantly lower in the IMRT group than in the 2DRT group.

Conclusion: IMRT demonstrated an improved ultimate therapeutic ratio compared with 2DRT in patients with NPC after a 10-year follow-up, with significant improvement of L-FFS, FFS, and OS and decrease in most late toxicities.

Implications For Practice: The ultimate therapeutic ratio of intensity-modulated radiotherapy versus two-dimensional radiotherapy in patients with nasopharyngeal carcinoma is unclear. In this retrospective study of 1,276 patients with nonmetastatic nasopharyngeal carcinoma with a follow-up of 115 months, intensity-modulated radiotherapy demonstrated an improved ultimate therapeutic ratio compared with two-dimensional radiotherapy, with significant improvement of local failure-free survival, failure-free survival, and overall survival and decrease in most late toxicities and noncancer deaths. However, distant control remains insufficient with this treatment modality.