Nasopharyngeal intracavitary brachytherapy: the controversy of T2b disease

Background: Locally persistent nasopharyngeal carcinoma (NPC) carries an increased risk of local failure if additional treatment is not given. It has been shown that intracavitary brachytherapy is effective in the treatment of patients with T1 and T2a NPC, although its role in the treatment of T2b disease had remained uncertain. The objectives of the current study were to evaluate the outcomes of patients with T2b, locally persistent NPC who were treated with high-dose-rate (HDR) intracavitary brachytherapy and to explore whether routine brachytherapy boost could improve the local control of patients who had T2b NPC at initial diagnosis.

Methods: Thirty-four patients with locally persistent NPC who were treated during 1992-2000 with HDR intracavitary brachytherapy were analyzed retrospectively. All patients had T2b disease at initial diagnosis. They were treated with HDR intracavitary brachytherapy at doses of 22.5-24.0 grays (Gy) in 3 weekly sessions. To compare the efficacy of brachytherapy, another 403 consecutive patients with nonmetastatic T2b NPC who were treated with curative intent by external radiotherapy (ERT) during the same period were evaluated.

Results: An improvement in the 5-year actuarial local failure-free survival rate (brachytherapy group vs. ERT group: 96.9% vs. 81.5%; P = 0.024), the disease-specific survival rate (84.5% vs. 68.1%; P = 0.021), and the overall survival rate (78.3% vs. 63.1%; P = 0.034) was demonstrated in the group that had locally persistent NPC who were salvaged with brachytherapy. In assessing local control, the addition of brachytherapy was just short of statistical significance on multivariate analysis (P = 0.054). The complication rates were comparable between the brachytherapy group and the ERT group.

Conclusions: The results suggested that patients with T2b NPC who have locally persistent disease can be salvaged effectively with brachytherapy. Their local control was even better than that achieved by patients who had clinical remission of local disease at the completion of ERT. Furthermore, it is possible that routine brachytherapy boost, after the completion of ERT, may improve local control in patients who have T2b disease at initial diagnosis. However, its exact benefit can be elucidated only by prospective, randomized studies.