DEATH RELATED TO PULMONARY METASTASIS IN PATIENTS WITH DIFFERENTIATED THYROID CANCER.

OBJECTIVE: The purpose of the present study was to investigate the predictive factors for shorter disease-specific survival in patients with pulmonary disease secondary to differentiated thyroid cancer (DTC). METHODS: This was a retrospective cohort study conducted over a 5-year period that included 54 patients with pulmonary disease secondary to DTC during the follow-up. Among these patients, 13 (24.1%) died from the disease. Dedifferentiation characteristics were identified at pathological examination of the metastatic disease (lymph node or distant metastases) and was defined as the abrupt transformation of a well-differentiated tumor into high-grade morphology lacking the original distinct histologic characteristics. RESULTS: Tumor dedifferentiation marked by cellular aberrations and radioiodine (RAI) therapy resistance occurred in 5 (9.3%) patients. Four of them died due to pulmonary progression (80.0%), and the median survival of this group was 30 months compared to 279 months in the patients without dedifferentiation. The cumulative disease-specific survival was 20.0% in the patients with dedifferentiation during the follow-up versus 46.1% among the cases without this condition (P = .003, log-rank test). Moreover, dedifferentiation was independently associated with shorter disease-specific survival (hazard ratio [HR] = 31.607; 95% confidence interval [CI]: 4.815-207.478; P<.0001, Cox regression model) as were age over 45 years (HR = 10.904; 95% CI: 1.145-103.853; P = .038) and male sex (HR = 4.210; 95% CI: 1.056-16.783; P = .042). CONCLUSION: DTC patients with pulmonary disease exhibited shorter disease-specific survival, particularly those who developed tumor dedifferentiation, and these patients require special attention during follow-up. ABBREVIATIONS: CI = confidence interval DTC = differentiated thyroid cancer FTC = follicular thyroid carcinoma HR = hazard ratio IQR = interquartile range LN = lymph node LR = likelihood ratio PTC = papillary thyroid carcinoma RAI = radioiodine pTNM = pathologic tumor-node-metastasis stage system.