Predicting outcome and directing therapy for papillary thyroid carcinoma.

HYPOTHESIS The prognosis of papillary thyroid carcinoma has been stratified into low- and high-risk groups. Patients in the high-risk group can be substratified on the basis of increasing age, with implications for prognosis and treatment. DESIGN Retrospective study. SETTING Tertiary care center. PATIENTS A total of 727 patients with papillary thyroid cancer treated at Lahey Clinic, Burlington, Mass, from 1940 to 1998. INTERVENTIONS Stratification into low- and high-risk groups based on age, metastases, extent, and size. High-risk patients were substratified into "younger" and "older" high-risk groups by age younger than 60 years or 60 years and older, respectively. Effects of surgery, lymph node dissection, and radiation therapy were examined. Main Outcome Measure Survival. RESULTS Of the 727 patients, 585 (80.5%) were classified as low risk and 142 (19.5%) as high risk. The 20-year survival was 97.8% in low-risk patients and 61.3% in high-risk patients (P<.001); it was 72.3% in the younger high-risk group and 45.1% in the older high-risk group (P<.001). Older high-risk patients had a survival advantage with bilateral thyroidectomy: 54.7% 20-year survival for those undergoing bilateral thyroidectomy and 25.0% for unilateral thyroidectomy (P =.004). In the older high-risk group, patients with lymph node dissection (n = 22) had a 20-year survival of 72.4% vs 30.2% in patients who did not undergo lymph node dissection (n = 38) (P =.03). Twenty-year survival in low-risk, younger high-risk, and older high-risk patients receiving radioactive iodine vs no radiation was 100% vs 97.6% (P =.24), 64.2% vs 73.2% (P =.53), and 44.7% vs 44.4% (P =.53). CONCLUSIONS Papillary thyroid carcinoma in low-risk patients had a favorable prognosis regardless of treatment. Older high-risk patients had a survival benefit with total thyroidectomy and lymph node dissection. Radioactive iodine did not affect 20-year survival in any of the risk groups.