Purpose: Survival outcomes in patients presenting with well-differentiated thyroid cancer with pulmonary metastasis are variable. The aim of this study was to evaluate prognostic factors for outcome in this patient population. Methods: A prospective registry database was searched to identify patients presenting with pulmonary metastasis from well-differentiated thyroid cancer. All patients underwent total thyroidectomy and postoperative I-131 therapy. Cox proportional hazards modeling was performed to evaluate prognostic factors for survival outcomes. Results: Forty (40) patients were identified with well-differentiated thyroid cancer involving the thyroid and metastatic to cervical lymph nodes and lung at initial diagnosis. The median follow-up was 9.7 years for those alive at last follow-up. Cox proportional hazards modeling evaluated age at diagnosis, gender, primary tumor size, and vascular invasion on cause-specific and progression-free survivals. Age at diagnosis was the only significant independent prognostic factor (p = 0.0035). The 10-year cause-specific survivals were 100% in patient's ≤40 years, compared to 36% for those >40 years (p < 0.0001). The corresponding 10-year progression-free survivals were 69% and 12% (p = 0.0003). Conclusions: Patients ≤40 years of age presenting with pulmonary metastasis from well-differentiated thyroid cancer had an excellent prognosis. Older patients have a poor survival outcome. Postoperative I-131 therapy is recommended in all patients.
