Fifty‐eight cases of pulmonary metastases (PM) from 831 cases of differentiated thyroid carcinoma (DTC) were studied. PM were found in about 10% of follicular and 5% of papillary tumors. 131I uptake was found in 55% of the cases, irrespective of histology. Twenty‐one patients were treated by 131I only and 12 were cured. Micronodular metastases, 92% papillary, with 86% positive 131I uptake and 77% 8‐year survival rate, are the most favorable forms. In others the influence of PM size/age, uptake, delay of appearance, presence of cervical or mediastinal lymph nodes is discussed. Occurrence of late PM according to treatment of the primary tumor was 1.3% thyroidectomy + 131I; 3% thyroidectomy; 5% partial thyroidectomy + 131I; 11% partial thyroidectomy only. Thus prevention in DTC of severe PM (28% 8‐year survival rate) can best be achieved by complete thyroidectomy + 131I ablation dose.

Although iodine-induced thyrotoxicosis was reported to occur in patients with obvious underlying thyroid disorders, it is not known to occur in patients with apparently normal thyroid glands. From ten such cases evidence is presented that thyrotoxicosis: a) appeared during treatments by iodide or organic-iodine-containing drugs, in the absence of any past history of thyroid disorder; b) was accompanied by almost undetectable radioidine uptake which nevertheless could be activated by TSH; c) subsided spontaneously within a few weeks or months after stopping the high intake of iodine; d) and left, after a period of hypothyroidism, an apparently normal thyroid gland which had resumed normal size, function, uptake, and suppressibility.

Iodine-induced thyrotoxicosis was documented in eighty-five cases. Eighty per cent occur in apparently normal thyroid glands; 60% among them occur in males. Amiodarone accounted for 50% of iodine-induced thyrotoxicosis. Mean thyroid hormone levels at diagnosis were: FT1: 21.7 (normal mean: 7.5, arbitrary units); T3: 4.53 nmol 1(-1) (normal: 2.30 nmol 1(-1). Mean 131I- 24-h uptake was 3.5% (normal range in France 25-45%) and was activated by exogenous TSH (mean 27%). The spontaneous cure in nontreated cases was observed within an average 6 months. A phase of biological hypothyroidism (mean FT1: 3.7, T3: 1.23 nmol 1(-1), TSH: 9.6 microU ml-1 (normal TSH range: 1-7 microU ml-1] preceded the return to euthyroidism. Intrathyroid iodine content measured by X-ray fluorescence was high, then fell gradually. Thyroid tissue study showed a large quantity of intrathyroid iodine and the overiodination of thyroglobulin. Histological and electron microscopic studies are reported. Prednisone and in some cases propylthiouracile were found to be effective.

A multivariate analysis of prognostic factors has been carried out with 375 cases of differentiated thyroid cancer (DTC) treated in the same centre by total thyroidectomy and 131I therapy. The patients have been followed for 5 to 23 years. The isolated prognostic roles of age, sex, clinical stage and histology were confirmed, but these factors were found to be strongly interrelated. Multifactorial analysis was conducted following Cox's model. It demonstrated that the prevalent role of clinical staging (nodular versus lobar or massive form) is as important as the initial presence of metastases (P = 0.0001). Histological assessment of differentiation, age and sex were of lesser importance. Thus, the most significant prognostic variable is clinical stage. These data must be taken into account when formulating management protocols for DTC.