High-dose external beam radiotherapy controlled locally advanced, differentiated thyroid cancer in a retrospective study of 42 patients.
There is little information on the efficacy of external beam radiotherapy (EBRT) as adjuvant therapy in such patients. “The relatively low incidence of this malignancy, coupled with its long natural history, has precluded study of various treatment methods in the context of a prospective clinical trial,” said Dr. Kenyon M. Meadows and his associates at the University of Florida, Gainesville.
“Retrospective outcome studies remain the most reliable way of assessing therapeutic efficacy but are hampered by significant heterogeneity in diagnostic evaluation, staging, and treatment strategies that have evolved over time. Accordingly, the indications for EBRT for differentiated thyroid cancer remain poorly defined,” they said.
The 10% of thyroid cancer patients presenting with locally advanced disease are at high risk for local or regional recurrence. Five-year survival is 50%.
The investigators reviewed the records and assessed outcomes in all 42 patients who were treated for advanced or recurrent thyroid cancer with adjuvant high-dose EBRT at their university since April 1962. Median patient age was 58 (Am. J. Otolaryngol. 2006;27:24–8).
Ten patients died from thyroid cancer during a mean follow-up of 7 years and 16 died from unrelated causes. There were no local or regional recurrences at 5 years for patients with no gross residual disease at EBRT and 30% recurrence for those with gross residual disease at EBRT. No recurrences were seen with doses over 64 Gy.
Five-year survival free of distant metastases was 82% in those without metastasis at EBRT.