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Papillary thyroid microcarcinoma (PTMC), a tumor measuring =or1 cm according to the World Health Organization (WHO) histologic classification, is the most common histologic variant of thyroid cancer. The aim of this study was to evaluate the long-term outcome of surgical treatment for PTMC at a single institution with a view to differentiate therapy options based on risk of progression of disease by comparing our results with those reported in the literature.The study sample was a total of 587 cases of PTMC treated surgically at our institution between 1990 and 2006. PTMC was an incidental finding (PTMC-I) in 325 (55.4%) cases, diagnosed preoperatively (PTMC-D) at echography and needle-aspiration biopsy in 229 (39%), and occult with metastasis (PTMC-O) in 33 (5.6%). Patients were grouped into two classes (PTMC diameter =or5 mm or5 mm) and compared against prognostic factors: sex, age, type of PTMC (PTMC-I, PTMC-D, PTMC-O), extent of surgery, lymph node dissection, lymph node metastasis, iodine-131 (131-I) therapy, state of disease, relapses. These parameters were then compared against tumor size (PTMC diameter =or5 mm or5 mm), excluding cases of PTMC-O with metastasis.Comparison of the two groups divided by tumor size, across the entire sample and after PTMC-O cases were excluded, revealed significant differences in the type of PTMC, frequency of partial thyroidectomy, presence of lymph node metastasis, iodine-131 therapy, life status and recurrence rate.Published PTMC studies were analyzed for definition of the disease, incidence, therapy, prognosis, and follow-up results and compared with our data. The results of our analysis argue against use of the term ''microcarcinoma'' in the wider sense since the three PTMC categories (PTMC-I, PTMC-D, PTMC-O) present different behaviour patterns. When cases of PTMC-O with clinically manifest metastasis were excluded, none of the patients with PTMC5 mm in diameter were reoperated for tumor recurrence and all are currently free of disease. In conclusion In PTMC5 mm in diameter, whether PTMC-I and PTMC-D, and without evidence of lymph node involvement, partial thyroidectomy may be a viable approach to treatment. By contrast, occult PTMC with metastasis is prognostically important and should therefore be treated like tumors =or5 mm in diameter. |
