High dose rate brachytherapy for early stage oral tongue cancer.

Background: High dose rate (HDR) interstitial brachytherapy of the oral tongue is a new treatment modality. Our study evaluates the outcomes of patients with early stage oral tongue cancer as treated by HDR interstitial implant.

Methods: We reviewed the records of 19 patients who were seen between 1994 and 2000 with carcinoma of the oral tongue and whose primary tumors were treated solely with interstitial implant using HDR remote afterloading technique. Ten patients had T1 N0 disease, and the remaining 9 had T2 N0 disease. Elective neck treatment was withheld for 12 patients. The remaining seven patients had ipsilateral elective neck dissection. The male-female ratio was 1:0.9, and the median age was 60 years (range, 32-81 years). The median follow-up time was 43 months (range, 6-78 months). The afterloading catheters were positioned by the submandibular approach with the assistance of a template set. Fifteen patients had single planar implants, and the remaining four had double planar implants. The median number of catheters inserted was 5 (range, 4-9). The median dose given was 55 Gy in 10 fractions over 6 days. The minimal interfraction interval was 7 hours for the first 7 patients and was extended to 8 hours for the other 12. Mandibular shields were inserted before treatment.

Results: The mucositis lasted for 6 to 20 weeks (median, 9 weeks). One patient had local failure, and the 4-year local failure-free survival rate was 94.7%. Three of the 12 patients without elective neck treatment had ipsilateral regional failure develop. They were salvaged by neck node dissection and regionally remained in control. One patient with multiple nodal metastases and extracapsular spread had biopsy-proven liver metastases and died 6 months after implant. One of the seven patients who were treated with elective neck dissection had multiple nodal metastases and extracapsular spread. She was treated with postoperative radiotherapy to the neck. She died 30 months after implant with evidence of regional and distant failure. One patient treated with double planar implant had grade II necrosis of the soft tissue and bone develop. The necrosis resolved with conservative treatment. Another four patients had small area of soft tissue deficit of the tongue attributed to aggressive debulking or biopsy before brachytherapy.

Conclusions: Our experience in treating early stage tongue cancer with HDR remote afterloading technique is encouraging, because it gives a local control rate of 94.7% at 4 years with acceptable morbidity. Further studies are eagerly awaited to delineate the optimum schedule for this new treatment modality.