Intermediate-risk group for differentiated carcinoma of thyroid.

BACKGROUND: We have previously described prognostic factors in differentiated carcinoma of the thyroid gland relating to age, size and extrathyroid extension of the tumor, histologic grade, gender, and distant metastasis. These factors have identified patients in the low-risk group with excellent prognosis and the high-risk group with significant mortality. However, some patients fall within the intermediate-risk category where due deliberation in decision making is required for selection of appropriate treatment.
METHODS: A retrospective review of a consecutive series of 1038 previously untreated patients with differentiated carcinoma of thyroid treated during a period of 55 years was undertaken. Data gathered from review of the charts were subjected to univariate and multivariate analysis to assess prognostic factors. On the basis of the patient's age, presence of distant metastasis, and size, grade, and histologic characteristics of the tumor they could be classified into low-, intermediate-, and high-risk categories. Thus 403 (39%) patients were in the low-risk group, 232 (22%) patients in the high-risk category, and 403 (39%) patients in the intermediate-risk category.
RESULTS: With a median follow-up of 20 years, 99% survival was achieved in the low-risk group, whereas only 57% survived in the high-risk group. Interestingly, in the intermediate-risk category of 403 patients, the 20-year survival was only 85%. Our results clearly identify a distinct intermediate-risk category that includes low-risk patients with high-risk tumor or high-risk patients with low-risk tumor.
CONCLUSION: Patients in the intermediate-risk category should be considered for an aggressive treatment approach based on individual prognostic factors.