A prospective, randomized study comparing outcomes and toxicities of intensity-modulated radiotherapy vs. conventional two-dimensional radiotherapy for the treatment of nasopharyngeal carcinoma

Background and purpose: To compare clinical outcomes and toxicities of two-dimensional conventional radiation therapy (2D-CRT) and intensity modulated radiation therapy (IMRT) for the treatment of nasopharyngeal carcinoma (NPC).

Materials and methods: Between July 2003 and October 2008, 616 patients with non-metastatic stage I to IVb NPC were prospectively randomized to receive 2D-CRT (n=310; mean age, 44.8±13.6 years) or IMRT (n=306; mean age, 46.7±12.5 years). Clinical outcomes and acute and late toxicities were determined and compared.

Results: The 2 groups were comparable with respect to all parameters of demographics and disease characteristics (all, p>0.05). Median follow-up was 42 months (range, 1-83 months). The 5-year actuarial local control rate was 90.5% in the IMRT group and 84.7% in the 2D-CRT group. The local control rates were 91% for stage T3 and 81.5% for stage T4 disease in the IMRT group and 80% and 62.2% in the 2D-CRT group, respectively. The 5-year actuarial nodal relapse-free survival (NRFS) rate was 92.4% in the IMRT and 92.9% in the 2D-CRT group (p>0.05). The NRFS was 93.9% for N2 disease in the IMRT group and 91.4% in the 2D-CRT group (p=0.02). The 5-year overall survival (OS) rate was 79.6% for the IMRT group and 67.1% for the 2D-CRT group (p=0.001). When stratified for stage, a significant difference was only noted for stage III disease. In terms of radiation-induced toxicities, patients in IMRT group had significantly lower radiation-induced toxicities than those in 2D-CRT group.

Conclusion: IMRT provides improved local-recurrence free survival, especially in late-stage NPC patients and is associated with a lower incidence of toxicities.