Medullary thyroid cancer: the role of radiotherapy in local control.

Fifty-one patients were treated with radiotherapy for loco-regional medullary thyroid cancer between 1960-1992. The actuarial overall survival at 5, 10 and 20 years was 69%, 52% and 30%, respectively. Patients were classified according to clinical stage (node-positive or -negative), post-operative histological residual disease status (none, microscopic or macroscopic) and dose of radiotherapy received. By univariate analysis, loco-regional recurrence-free survival was significantly longer for node-negative patients (P = 0.03). Patients who received at least 60 Gy over 6 weeks showed a trend towards improved local control (P = 0.23). The only significant variable by multivariate analysis for local recurrence-free survival was post-operative residual disease status (P=0.0005). The local control rate at 5 years was 100% for patients with no residual disease, 65% for those with microscopic tumour, and 24% for those with macroscopic residual disease. We conclude that there is a valuable role for radiotherapy in the management of patients with residual microscopic or macroscopic disease following surgery, as well as in those with inoperable disease.