Clinical management and outcome of papillary and follicular (differentiated) thyroid cancer presenting with distant metastasis at diagnosis.

Abstract

Differentiated thyroid cancer has a good prognosis and only rarely presents with distant metastasis at diagnosis. The clinical outcome of this presentation was assessed with respect to survival and factors that may determine prognosis. A retrospective review was undertaken of patients with stage M1 differentiated thyroid cancer at presentation (n = 49), referred from 1980-2000 at a single institution. The median age was 68 (range, 17-90), with 69% females. The initial site(s) of metastasis were lung only, 45%, bone only, 39%, other single site, 4%, and multiple sites, 12%. papillary, 51%, follicular, 49%. Initial treatment(s) included: thyroidectomy, 82%, radioactive iodine (RAI), 88%, excision of metastasis, 29%, radiotherapy, 47%, and chemotherapy, 6%. With a median follow-up time of 3.5 years, 25 patients are alive (51%) and 24 died (49%), with 3-year and 5-year actuarial survivals of 69% and 50%, respectively. Only a minority of patients (4/25, 16%) had no clinical evidence of disease at last follow-up. Most deaths (17/24, 71%) were due to progressive cancer. Prognosis was associated with age, site of metastasis, histology, and iodine avidity of the metastasis. Patients aged </=45 (n = 8) had a 3-year survival of 100%, versus 62% for those age > 45 years (P = .001). The 3-year survival for lung only versus bone only metastasis was 77% versus 56% (P = .02); for papillary versus follicular carcinoma, 75% versus 62% (P = .006); for iodine-avid disease (n = 29) versus not avid (n = 14), 82% versus 57% (P = .02), respectively. In multivariate analysis after adjusting for age, only histology and iodine avidity remained significant for survival. The hazard ratio for follicular histology was 3.7 (95% confidence interval [CI], 1.1-12.1, P = .03), and for tumors not avid for iodine, 3.4 (95% CI, 1.2-9.2, P = .02). The data support the aggressive management of patients presenting with stage M1 thyroid cancer, with thyroidectomy and RAI. Complete clinical eradication of disease was rarely seen, and 50% of patients survived for more than 5 years. Young patients with papillary tumors and/or iodine-avid disease have an even better prognosis.