Recurrent thyroid cancer. Role of surgery versus radioactive iodine (I131)

This retrospective study compared treatment and survival of patients with recurrent well-differentiated thyroid cancer that was diagnosed exclusively by I131 scanning, or by clinical examination.

Despite the usual excellent prognosis of differentiated thyroid cancer, approximately half of patients who developed a recurrence eventually succumb to the disease. It has been speculated, but not proven, that recurrent disease detected solely by I131 scanning may offer a better prognosis than recurrences detected clinically and be amendable to I131 ablative therapy without the addition of surgical resection.

Seventy-four cases of recurrent differentiated thyroid cancer were identified retrospectively and examined regarding the location of recurrence, mode of detection of recurrent disease, treatment of recurrence, and outcome of patients. Using Fischer exact testing, outcome results for recurrences detected exclusively by I131 scan was compared to that of clinically diagnosed recurrences; among clinically detected recurrent cases, treatment with surgery only was compared to surgery/I131 ablation. Kaplan-Meier actuarial survival curves were generated for clinically detected recurrent cancer treated by surgery only and compared to those treated by surgery and I131 ablation using Gehan-Wilcoxon and log-rank analysis.

Recurrences located most commonly were regional (53%), followed by local (28%), distant metastasis (13%), and combined locoregional (6%). Among patients whose recurrence was detected scintigraphically, only 9.5% had persistence of disease or were dead of disease compared to 54.0% of patients with clinically detected recurrences. Radioactive iodine ablation in scintigraphically detected recurrences salvaged 18 of 20 patients (90%). Among clinically detected recurrences, surgery alone salvaged 12 of 21 patients (57%), whereas the addition of I131 ablation to surgery salvaged only 3 of 15 patients (20% p = 0.05).

The probability of dying or living with persistent disease after treatment of recurrent thyroid cancer is less for I131 detected recurrences compared to clinically diagnosed recurrences; I131 ablation without surgery constitutes adequate therapy for scintigraphically detected recurrences. In clinically recurrent disease, the addition of I131 ablation to curative resection does not appear to improve survival.