[A matched cohort analysis of three-dimensional conformal radiotherapy versus conventional radiotherapy for primary nasopharyngeal carcinoma].

Background & Objective: Comparing with two-dimensional conventional radiotherapy (2D CRT), three-dimensional conformal radiotherapy (3D CRT) features a precise tumor target volume positioning and a three-dimensional display of the tumor and surrounding normal tissues, therefore, helps to spare normal tissues in the radiotherapy for nasopharyngeal carcinoma (NPC). This study was to explore whether 3D CRT can increase the locoregional control rate while reduce the occurrence and severity of radiation-related sequelae for primary NPC patients.

Methods: Clinical data of 95 primary NPC patients, treated by 3D CRT from Feb. 2001 to Apr. 2004, were reviewed. These patients were then compared with a cohort of 95 NPC patients treated by 2D CRT from Jan. 2002 to Dec. 2003, who were matched in respect of 92 Fuzhou stage, T stage, N stage, sex and age. The short-term and long-term outcomes and radiation-related sequelae of the two groups were compared.

Results: There was no significant differences in the 5-year locoregional control rate (89.7% vs. 90.6%, P=0.783), local control rate (91.8% vs. 92.8%, P=0.758), regional control rate (95.6% vs. 97.8%, P=0.427), and distant metastasis-free survival rate (93.1% vs. 86.4%, P=0.152) between 3D CRT group and 2D CRT group. The 5-year overall and progression-free survival rates were slightly higher in 3D CRT group than in 2D CRT group (91.9% vs. 82.0%, P=0.072; 85.7% vs. 71.0%, P=0.087). Eighty-one patients in 3D CRT group and 70 patients in 2D CRT group who had survived without disease progression were compared in respect of late radiation-related sequelae. The occurrence rates of moderate or severe xerostomia and trismus were significantly lower in 3D CRT group than in 2D CRT group (37.0% vs. 71.4%, P<0.001; 6.2% vs. 28.6%, P<0.001). But there were no differences in functional impairment of hearing, memory and injury of cranial nerves between these two groups.

Conclusion: Comparing with 2D CRT, 3D CRT can reduce the occurrence of late radiation-related sequelae, such as xerostomia and trismus, for primary NPC, and it is likely to prolong overall and progression-free survival.