High-dose-rate brachytherapy using molds for oral cavity cancer: The technique and its limitations

Background. With the availability of a high-dose-rate (HDR) remote afterloading device, a Phase I/11 protocol was initiated at our institution to assess the toxicity and efficacy of HDR intracavitary brachytherapy, using molds, in the treatment of squamous cell carcinomas of the oral cavity.Methods. Eight patients with squamous cell carcinoma of the oral cavity were treated by the technique. The primary sites of the tumors were the buccal mucosa, oral floor, and gingiva. Two of the buccal mucosal cancers were located in the retromolar trigon. For each patient, a customized mould was fabricated, in which two to four afterloading catheters were placed for an ¹⁹²Ir HDR source. Four to seven fractions of 3–4 Gy, 5 mm below the mould surface, were given following external radiation therapy of 40–60 Gy/2 Gy. The total dose of HDR brachytherapy ranged from 16 to 28 Gy.Results. Although a good initial complete response rate of 7/8 (88%) was achieved, there was local recurrence in four of these seven patients. Both of the retromolar trigon tumors showed marginal recurrence. No serious (e.g., ulcer or bone exposure) late radiation damage has been observed thus far in the follow up period of 15–57 months.Conclusions. High-dose-rate brachytherapy using the mold technique seems a safe and useful method for selected early and superficial oral cavity cancer. However, it is not indicated for thick tumors and/or tumors located in the retromolar trigon.