High dose rate intracavitary brachytherapy in the treatment of nasopharyngeal carcinoma

A retrospective study on 61 patients, with local persistent or recurrent nasopharyngeal carcinoma (NPC), treated during 1990-1992 with high dose rate intracavitary brachytherapy alone or combined with external irradiation, is presented. All 39 patients with persistent disease were treated solely with brachytherapy. The actuarial 3-year local failure-free survival (LFFS) rates of the persistent and recurrent groups were 82% and 45% respectively. The corresponding disease specific survival rates were 82% and 62%. Fifteen patients with recurrence received the combined modality treatment and their 3-year LFFS rate was 65%. Three out of 7 patients treated by brachytherapy could be controlled locally. The total dose given to the floor of sphenoid was an important predictor of local control. Of the 23 patients with persistent disease treated with <17.5 Gy to this area, 6 failed locally as opposed to none of the 16 patients receiving a higher dose (p=0.031). For those with recurrence treated by the combined modality, none of the 7 patients given ≥57.5 Gy recurred while 5 local failures were observed among those receiving a smaller dose (p=0.041). The general implications of these results for the treatment of NPC recurrence are discussed. (orig.)