Surgical treatment of papillary and follicular thyroid carcinoma.

There is limited clinical information about the prognostic factors in survival and distant metastasis for well differentiated thyroid cancer in Chinese patients. Pitfalls were noted when applying the results of published studies to another population. In order to realize the differences of these factors between different areas, we retrospectively analyzed the data of 569 papillary or follicular thyroid carcinoma patients who received their primary treatment at the Chang Gung Memorial Hospital during the period from January 1979 to June 1994. Actuarial survival rates were calculated by the Kaplan-Meier method. For the analysis of prognostic variables, 14 clinical parameters were coded into the computer for the univariate and multivariate analyses. Multivariate analysis was performed to assess the independent effect of these variables using the Cox model. Among these cases, there were 466 papillary thyroid carcinoma (81.9%), 103 cases of follicular thyroid carcinoma (18.1%). The subjects included 440 female patients with mean age of 38.8 +/- 14.4 years and 129 male patients with the mean age of 44.7 +/- 14.4 years (p = 0.0001). Most of the cases received total thyroidectomy treatment after the diagnosis was confirmed by a frozen section during the operation. In the follow-up period, 30 (5.3%) patients died of metastatic thyroid cancer. The one year Greenwood survival probability after the disease diagnosed in papillary and follicular thyroid carcinomas was 0.986 and 0.909 respectively. Using a log-rank univariate analysis, survival was significantly associated with the histological type of primary tumors, age, clinical staging, post-operative 131I pattern, tumor size, postoperative serum thyroglobulin (Tg) level and post-operative X-ray findings. Tumor size larger than 2.5 centimeters could influence both the survival and distant metastases of these well differentiated thyroid cancer patients. In the Cox multivariate regression analysis, the combination factors that gave the best prognostic values were the association of distant metastasis (0.005), age (p = 0.027), and one month postoperative serum Tg level (p = 0.042). Well differentiated thyroid cancer is not an unusual disease in Taiwan. In this limited period of follow-up study, distant metastasis at the time of surgery, the patients' age and one month post-operative serum Tg level may serve as the prognostic factors for the well differentiated thyroid cancer patients.