Post-treatment follow-up of differentiated thyroid cancer.

The prognosis of differentiated thyroid carcinoma mainly depends on the qua lity of the initial treatment and on early detection and management of any recurrences. Study aim: The aim of this retrospective study was to assess the modalities and duration of surveillance in these patients according to an original cl assification based on the initial extent of the tumour. Patients and method: The modalities of detection of local recurrences and m etastases and the date of the latest recurrences were assessed in a series of 509 patients with a mean follow-up of 8.2 years (range: I to 25 years). Most patients were treated by total thyroidectomy, followed by a therapeuti c dose of radioactive iodine. The other patients with a small localized car cinoma underwent partial thyroidectomy without radioactive iodine. Patients were divided into four groups on the 7th postoperative month after follow- up scintigraphy and thyroglobulin assay: group I: microcancers (n = 117), g roup II: cancer without lymph node involvement or metastasis and normal thy roglobulin divided into IIA, age < 45 years (n = 100) and IIB, age > 45 (n= 94), group III: cancer with lymph node involvement and normal thyroglobulin (n = 102), group IV: high-risk cancers with metastases or regional extensi on other than lymph node extension or thyroglobulin > 3 mug/L (n = 96). Results: Cancer-dependent actuarial survival rates for groups I, IIA, IIB, III, IV were 100%, 100%, 96%, 100%, and 73% at 10 years and 100%, 100%, 92% , 100%, and 86% at 15 years, respectively. Local or metastatic recurrences were sometimes detected by a single follow-up examination, while the other examinations were negative: cervical palpation, thyroglobulin assay, iodine scintigraphy, chest X-rays. The latest recurrences were observed at 12 yea rs in groups I and IIA and at 16 years in groups IIB, Ill, and IV with norm al thyroglobulin. Conclusion: This study confirms the importance of weaning thyroglobulin ass ays and scintigraphy which must be repeated every 5 years. Cervical palpati on, thyroglobulin assay without weaning, chest X-rays may also detect recur rences. Duration of follow-up must be adapted to the initial extension and subsequent course: 15 years in groups I and IIA, 20 years in groups IIB, II I, and IV with normal thyroglobulin, for at least 10 years after each recur rence, and life-long in the case of progression and thyroglobulin > 3 mug/L . Patients must be informed about the duration of follow-up at the 7th mont h when the definitive classification can be established and continuity of t his follow-up must be documented in a special register. (C) 2000 Editions s cientifiques et medicales Elsevier SAS.