A Clinical Analysis of Recurrence in Differentiated Thyroid Carcinoma

Seong, Nak Yoon; Lee, Yong Sik; Shim, Yoon Sang; Lee, Guk Haeng; Lee, Byeong Cheol; Kim, Kwang Il; Kim, Heon Dae

Abstract

BACKGROUND AND OBJECTIVES
Differentiated thyroid carcinoma (DTC) is a known malignant tumor arising from the follicular epithelium in thyroid gland. Although the prognosis for patients with DTC is generally good, appropriate surgical management can further reduce recurrence and cancer death rates significantly. The therapeutic methods performed are total thyroidectomy plus radioactive iodine (131I) therapy and life-long thyroid-stimulating hormone (TSH) suppression. Histopathologically, DTC contains papillary and follicular adenocarcinoma. In numerous studies, staging systems-AMES, AGES, MACIS, etc-have been created to evaluate prognostic outcome. By applying staging systems, we have treated 394 patients with DTC since 1998. The purpose of our study was to analyze characteristics of recurrent cases and evaluate remission rates of recurrent cases according to diagnostic methods. MATERIALS AND METHOD: From January 1998 to December 2001, we performed 630 thyroidectomies and 487 malignant tumors (421 papillary, 28 follicular, 20 medullary, 12 undifferentiated carcinoma and 6 other malignant tumors). We analyzed 394 DTC cases; excluding other malignancy, 65 cases were recurrent cancer (58 papillary and 7 follicular carcinoma). The medical records of 394 patients with DTC treated at our hospital were reviewed retrospectively. We analyzed impact of primary surgery on recurrence in 65 recurrent patients and compared the remission rates of those patients using physical examination with those using laboratory tests and imaging studies. RESULTS: 347 patients with DTC were treated initially in our hospital and 18 patients showed recurrence. Among them, lobectomy was performed as a primary surgery in 69 patients of whom one (1.4%) had recurrence. Forty-seven patients with DTC treated initially in other hospitals were referred to our hospital. Lobectomy was performed as a primary surgery in 23 patients (54.7%). Recurrence of 32 patients was detected by palpation. Of these patients, the remission rate was 25.0%, whereas patients diagnosed by laboratory tests and imaging systems showed 53.3% remission rate (p=0.056). CONCLUSION: The extent of primary thyroid resection appeared to have significant impact on the recurrence of DTC. In view of this, we should apply staging system strictly in treating DTC-total thyroidectomy and central neck dissection in high-risk groups. In following up patients, we should check the thyroglobulin level and use image tests like computed tomography and positron emission tomography to detect recurrence earlier.