Iridium 192 implantation of T1 and T2 carcinomas of the mobile tongue

Abstract

Between 1970 and 1986, 166 patients with T1 or T2 epidermoid carcinomas of the mobile tongue were treated by iridium 192 implantation (70 T1N0, 83 T2N0, 13 T1-2 N1-3). Five-year actuarial survival was 52% for T1NO, 44% for T2aNO, and 8% for or T1-2 N1-3. Cause specific survivals were 90%, 71%, and 46%, respectively. Local control was 87% for both T1 NO and T2NO, and 69% for T1-2 N1-3. Seven of 23 failures were salvaged by surgery, increasing local control to 96% for T1 and 90% for T2. Thirty-six patients developed a minor or moderate necrosis (16% Tl, 28% T2). Half of these involved bone but only five required surgical intervention. Both local control (LC) and necrosis (nee) increased with increasing dose but improvement beyond 65 Gy is minimal (≤60 Gy: LC = 78% nec = 13%; 65 Gy: LC = 90% nee = 29%; ≥70 Gy: LC = 94% nee = 23%). For NO patients, neck management consisted of surveillance (n = 78), elective neck dissection followed with external irradiation for pathologically positive nodes (n = 72), or irradiation (n = 3). Clinically positive nodes (13 patients) were managed by either neck dissection followed by external irradiation if pathologically positive (n = 10) or irradiation alone (n = 3). Regional control was 79% for NO patients, improving to 88% after surgical salvage, and was 9/13 for N1-3 patients. We recommend that T1 and T2 carcinomas of the mobile tongue be treated by iridium 192 implantation to deliver 65 Gy. Mandibular necrosis should be reduced by using an intra-oral lead-lined dental mold.