Distant metastases in papillary thyroid cancer. A review of 91 patients.
Of 731 patients with papillary thyroid cancer, 91 had metastases outside regional lymph nodes. The most common site was intrathoracic, occurring in 73 of the 91 patients. Miliary, micronodular pulmonary metastases, with iodine 131 (I-131) uptake and "curable" by I-131 treatment were encountered in seven patients. It has not been established whether this was a transient stage in additional patients. In 38 patients rounded, macronodular pulmonary metastases were found. Another 21 patients had unilateral pulmonary infiltration and mediastinal enlargement. Pulmonary infiltrations may be hematogenic, or may possibly occur via regional, mediastinal lymph nodes. Mortality within 1 year of the diagnosis of distant metastases exceeded 50%. Occurrence of distant metastases showed a slight but highly significant association with male sex, advanced age, and advanced local tumor stage. Better prognostic determinants are, however, required if adequate of the individual patient with papillary thyroid cancer is to be achieved.