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. Highrisk 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 highrisk group (P < .001). Older high-risk patients had a survival advantage with bilateral thyroidectomy: 54.7% 20year 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 (h = 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.