Clinical experience in the diagnosis of 127 papillary thyroid microcarcinomas

To investigate the difficulties in the diagnosis of thyroid microcarcinoma and to present the results of delaying diagnosis for these patients, we retrospectively analyzed the clinical information of 1259 thyroid carcinoma patients in one medical center. During a period of 20 years, from January 1977 to June 1997, 1259 thyroid cancer patients, including 921 papillary thyroid carcinoma patients, who received treatment and were followed-up at Chang Gung Medical Center in Linkou, Taiwan, were evaluated for inclusion in the study. Of these patients, 127 (13.2%) were diagnosed as having thyroid microcarcinoma. Forty-five patients were diagnosed as malignancy or suspicious malignancy preoperatively with ultrasonography and fine needle aspiration cytological examinations. In the analysis, the 127 thyroid microcarcinoma patients who received surgical treatment could be divided into four groups. Group I: patients with thyroid microcarcinoma with hyperthyroidism or hyperparathyroidism, in most of whom (except four patients) the thyroid microcarcinoma was found incidentally during the operation (28 cases). Group II: thyroid microcarcinoma in benign larger thyroid nodule or multinodular goiter, or thyroid microcarcinoma in coexistence with nodule goiter in one patient. The thyroid microcarcinomas in this group were found incidentally except in five patients (58 cases). Group III: thyroid microcarcinoma which could be detected as thyroid nodule preoperatively (28 cases). Group IV: thyroid microcarcinoma presented with neck lymph node metastases or distant metastases of the thyroid carcinoma (13 cases). Median follow-up period of these 127 patients was 4.7 years. During the follow-up period, two patients died, including one patient in group IV who died of skull metastasis with brain invasion. Another patient died of stroke, which was, however, not related to thyroid carcinoma. In conclusion, most thyroid microcarcinoma patients experienced rather benign clinical courses, but for patients with thyroid microcarcinoma with distant metastases, aggressive surgical treatment followed by radioactive 131I treatment is indicated. Endocrine-Related Cancer (1998) 5 239-245 Lin et al.: Thyroid microcarcinoma 240 microcarcinoma, which was defined as a welldifferentiated thyroid cancer not larger than 1.0 centimeter (≤1 cm). Of these 127 thyroid microcarcinoma patients, 94 received pre-operative thyroid ultrasonography with FNAC examinations. Thyroid ultrasonography studies were performed using a real time ultrasonographic machine with a 10 MHz transducer (ALOKA) (Lin et al. 1997a). For suspected thyroid nodule, FNAC examinations were performed with 22-gauge needles without local anesthesia. If profuse bleeding were encountered, the needle was replaced with a 25-gauge needle. The aspirates were placed in the center of frostedend glass slides, and were air-dried and stained by means of the Romanowsky-based Liu method (Tsou et al. 1997). All ultrasound and cytological results were interpreted by an attending physician at the Metabolism Division of Linkou Chang Gung Medical Center. Of the 127 patients, 75 patients received near total thyroidectomy, 41 received subtotal thyroidectomy, and 11 patients received lobectomy. During the operation, frozen sections were performed in 90 patients. After the operation, all the patients received long-term thyroid hormone replacement. Regular cancer check-ups consisting of a 5 mCi 131I whole body scan, chest X-ray, and serum thyroglobulin (Tg) levels were performed every 6 months. Once the metastatic or recurrent lesions were detected, either surgical treatment or 131I therapy was suggested. The majority of these patients received regular follow-ups in the Division of Endocrinology and Metabolism, Chang Gung Memorial Hospital. Admission records were reviewed and the following data were recorded using a computer: age, gender, primary tumor size, ultrasonographic findings, aspiration cytology results, thyroid function before the operation, results of 99mTc thyroid scan, operative methods, one-month postoperative serum Tg levels, percentage of 131I uptake after 5 mCi 131I cancer work up, post-operative chest X-ray findings, clinical staging for analysis of distant metastases by non-invasive examinations, results of treatments, and survival. Data are presented as means±S.D. and two-tailed, unpaired nonparametric t-tests, chi-square and ANOVA were used to evaluate the statistical significance of the data.