Improved local control for early T-stage nasopharyngeal carcinoma - a taleof two hospitals

Purpose: To study the efficacy of intracavitary brachytherapy (ICT) in earl y T-stage nasopharyngeal carcinoma (NPC). Methods and materials: All early T-stage (T1 and T2 nasal cavity tumour) NP C treated with a curative intent up to 1996 were analyzed (n = 743), 163 fr om the Prince of Wales Hospital (PWH) and 25 from Tuen Mun Hospital (TMH) w ere given ICT after radical external radiotherapy (ERT; group A). They were compared with 555 patients treated with ERT alone (group B). The radiother apy techniques were identical between the two hospitals. The ERT delivered the tumoricidal dose (uncorrected biological equivalent dose (BED)-10, grea ter than or equal to 75 Gy) to the primary tumour, and this did not differ in technique or dosage between the two groups. The ICT delivered a dose of 18-24 Gy in three fractions over 15 days to a point 1 cm perpendicular to t he midpoint of the plane of the sources. Results: The local failure was significantly less (crude rates, 6.9 vs. 13. 0%; 5-year actuarial rates, 5.8 vs. 11.7%) and the disease-specific mortali ty was significantly lower (crude rates, 13.8 vs. 18.9%; 5-year actuarial r ates, 12.2 vs. 15.2%) in group A compared with group B. ICT was the only si gnificant independent prognostic factor predictive of fewer local failures. When ICT was excluded from the Cox regression model, the total physical do se or the total BED-IO uncorrected for tumour repopulation became significa nt in predicting the ultimate local failure rate. The two groups were compa rable in the rate of the chronic radiation complications. A significant dos e-tumour-control relationship existed, plotting the local failure as a func tion of the total physical dose or the total BED. Conclusions: Supplementing ERT, which delivered the tumoricidal dose (uncor rected BED-10, greater than or equal to 75 Gy), with ICT significantly enha nced ultimate local control in early T-stage (T1/T2 nasal infiltration) NPC , A significant dose-tumour-control relationship exists above the conventio nal tumoricidal dose level. (C) 2000 Elsevier Science Ireland Ltd. All righ ts reserved.