Microcarcinoma of the thyroid gland

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Abstract
BACKGROUND Patients with thyroid microcarcinoma (TMC) have favorable long term prognoses. However, recurrences in the neck and distant metastases have been reported. The authors investigated independent factors associated with recurrence in an effort to define therapeutic guidelines. METHODS Two hundred eighty‐one patients (207 females, 74 males; mean age, 41.9 years) with a differentiated thyroid carcinoma ≤1 cm in greatest dimension (mean size ± standard deviation, 5.9 ± 3.3 mm) were analyzed. The median follow‐up time was 7.3 years. RESULTS TMC diagnosis was incidental in 189 patients, and metastases were the first manifestation of the disease in the other 92 patients. Therapy included near‐total thyroidectomy for 195 patients, lymph node dissection for 195, and therapeutic administration of radioiodine for 124. Eleven recurrences (3.9%) were observed 4.3 ± 2.7 years (mean ± standard deviation) after initial treatment: all had locoregional recurrence (4 in the thyroid bed and 7 in the lymph nodes), and in one of these the local recurrence was associated with lung metastases. Multivariate analysis showed that two parameters significantly influenced TMC recurrence, namely, the number of histologic foci (P < 0.002) and the extent of initial thyroid surgery (P < 0.01). Only 3.3% of patients with unifocal TMC treated with loboisthmusectomy had tumor recurrence. CONCLUSIONS The recurrence rate for TMC appears to be low (3.9%). In the authors' view, loboisthmusectomy is the treatment of choice for patients with TMC when only one focus of cancer is found histologically, and total thyroidectomy is the optimal treatment for patients with multiple foci. [See editorial counterpoint on pages 401‐2 and reply to counterpoint on pages 403‐4, this issue.] Cancer 1998;83:553‐559. © 1998 American Cancer Society.