Comparison of efficacy of intensity-modulated and conventional radiotherapy for nasopharyngeal carcinoma involving cervical vertebrae: analysis of 53 cases

Objective: To compare the efficacy and side-effects of intensity-modulated radiotherapy (IMRT) and conventional radiotherapy in treatment of nasopharyngeal carcinoma (NPC) involving cervical vertebrae. Methods: Twenty-four patients of NPC with cervical vertebra involvement underwent IMRT with the dose to tumor target of 72-74 Gy divided into 33 fractions (IMRT group), and 29 patients underwent conventional radiotherapy with the total dose to tumor target of 68-74 Gy/34-37 fractions (2D-CRT group). All the 53 cases accepted platinum-based concurrent chemotherapy of cisplatin plus fluorouracil and 4-6 cycles of adjuvant chemotherapy after the radiotherapy. Follow-up was conducted for 6 months to more than 7 years. Results: The 3-and 5-year overall survival (OS) rates of the IMRT group were 87.7% and 65.5% respectively, both significantly higher than those of the 2D-CRT group (45.5% and 9.1% respectively, χ² = 6.89, P < 0.05), and the 3-and 5-year local progression-free survival (LPFS) rates of the IMRT group were 87.4% and 49.4% respectively, both significantly higher than those of the 2D-CRT group (69.9% and 9.4% respectively, χ² = 13.26, P < 0.05), and there were no significant statistical differences in the 3-, and 5-year distant metastasis-free survival (DMFS) rates (94.4% vs 40.8% and 79.8% vs 30.4% respectively, χ² = 2.29, P > 0.05) between two groups. Analysis showed N stage (χ² = 8.53, P < 0.05) and radiotherapy protocol (χ² = 8.02, P < 0.05) as the independent prognostic factors for OS and LPFS. The incidence of grade 2 and 3 xerostomia of the IMRT group was 29.17%, significantly lower than that of the 2D-CRT group (65.52%, χ² = 7.11, P < 0.05). Whereas, there were no significant statistical differences between these 2 groups in the incidence rates of acute irradiation mucositis and bone marrow suppression. Conclusions IMRT improves the local progression-free survival and overall survival and reduces the incidence of grade 2 and 3 radiation-induced xerostomia in local advanced NPC with cervical vertebra involvement more effectively than conventional radiotherapy. However, it fails to reduce the incidence of distant metastasis. (authors)