title: Thyroid cancer and thyroiditis in Salta, Argentina: a 40-yr study in relation to iodine prophylaxis.
abstract: The natural history of thyroid cancer and thyroiditis in relation to iodine prophylaxis in the region of Salta, Argentina, where goiter is common was investigated over a time span of 40 yr. For analysis of thyroid cancer, the specimens were divided into two periods. The first 15 yr (59 cases), including 5 yr before prophylaxis, was compared with the second 25 yr (182 cases), a period well after salt iodination. Papillary carcinomas formed the largest group of tumors in both periods, with a significant increase in their proportion in the second period (44 vs 60%, chi(2): p < 0.05), while the percentage of follicular and undifferentiated carcinomas decreased and medullary carcinoma remained about the same. The ratio of papillary to follicular carcinoma rose from 1.7:1 in the first period to 3.1:1 in the second. Four thyroid lymphomas of non-Hodgkin's B-cell type occurred in the second period in females over age 50. A severe lymphoid thyroiditis was present in the two cases with assessable background thyroid tissue. The frequency of moderate to severe lymphoid infiltrate in females rose from 2 of 12 (16.6%) in the preprophylaxis period to 34 of 114 (28.0%) in the last 25 yr after prophylaxis. After salt prophylaxis, thyroiditis was more frequent in patients with papillary carcinoma (36.2%) than in those with nonpapillary tumors (14.7%) (chi(2), p < 0.02). These observations indicate that a high dietary intake of iodine may be associated with a high frequency of papillary carcinoma and thyroiditis, and that thyroiditis is more commonly associated with papillary carcinoma than with other thyroid tumors. The occurrence of non-Hodgkin's lymphomas only in the postprophylaxis period may be linked to an increase in thyroiditis.
authors.affiliation: Services of Pathology, Dr A Oñativia Endocrinology and Metabolism Hospital, Salta, Argentina. rubenharach@ciudad.com.ar
authors.forename: H Rubén
authors.initials: HR
authors.lastname: Harach
authors.forename: Dardo A
authors.initials: DA
authors.lastname: Escalante
authors.forename: Ernesto Saravia
authors.initials: ES
authors.lastname: Day
mesh_terms: D000328:Adult; D001118:Argentina / Q000453:epidemiology; D002277:Carcinoma / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D004032:Diet; D005260:Female; D006043:Goiter, Endemic / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D006801:Humans; D007455:Iodine / Q000008:administration & dosage* / Q000172:deficiency; D016393:Lymphoma, B-Cell / Q000453:epidemiology* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D013964:Thyroid Neoplasms / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D013967:Thyroiditis, Autoimmune / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control
chemical_list: D007455:Iodine