Follow-up of low risk patients with papillary thyroid cancer: role of neck ultrasonography in detecting lymph node metastases.

Persistent or recurrent disease is rare in low risk patients with papillary thyroid cancer, and follow-up of these patients is a matter of debate. Neck ultrasonography (US), serum thyroglobulin (Tg), and whole body scan (WBS) after T(4) withdrawal were performed in 456 patients, followed up to 5 yr. At the end of the first year, 335 patients were Tg negative, and 121 were Tg positive; 65 of 96 patients with Tg levels between 1 and 10 ng/ml became spontaneously Tg negative after 2 yr. During follow-up, WBS discovered node metastases in 13 subjects, and US discovered node metastases in 38 subjects (31 Tg positive and 7 Tg negative). WBS did not add any information, because all WBS-positive patients were also US and Tg positive. Fifty percent of metastases were less than 1 cm and not palpable. Finally, the negative predictive value of both negative Tg and US at first follow-up was 98.8%. We suggest a first follow-up based upon US assessment and stimulated (after T(4) withdrawal or recombinant human TSH) serum Tg determination; subsequently, 1) US should not be mandatory at each examination in initially Tg- and US-negative subjects, but is strongly suggested in all other cases; 2) Tg determination should be repeated 1 yr later, after exogenous or endogenous TSH stimulation only in initially Tg-positive patients without any other evidence of residual disease; and 3) Tg measurement during therapy should be sufficient in all other cases.