The relative roles of endemic goiter and socioeconomic development status in the prognosis of thyroid carcinoma.

BACKGROUND

It generally is accepted that the prognosis of thyroid carcinoma is more severe in areas in which goiter is endemic. It could be assumed that this prognosis also is less favorable in developing countries.

METHODS

Clinical features and tumor histology of 1000 consecutive patients were studied: Patient data from the endemic area (EA) were compared with those from the nonendemic area (NEA). In addition, patients from the years 1966-1981 (P1) were compared with those from 1982-1991 (P2). It is obvious that the country's socioeconomic status and health care system improved between the two periods.

RESULTS

The anaplastic and follicular types of thyroid carcinoma were more frequent in EAs (14% and 42.13%, respectively) than in NEAs (6.25% and 38.40%, respectively). The frequency of the anaplastic carcinoma during P1 (16.03%) decreased by half during P2 (7.79%), whereas the frequency of follicular carcinoma remained stable (35.85% and 40.46%, respectively). Clinically, more advanced stages (tumor size, local and distant disseminations) were observed in the study country than in developed countries. A clearcut improvement was observed during P2 whereas differences between the EA and NEAs were few. Survival rates (follicular and papillary types only) were not found to be different between EAs and NEAs (5-year survival: 81.44% and 75.32%, respectively; 10-year survival: 67.93% and 69.52%, respectively). A significant (P < 0.01) increase was observed between P1 and P2 (5-year survival: 72.69% and 84.80%, respectively; 10-year survival: 58.77% and 83%, respectively).

CONCLUSIONS

Compared with endemic goiter, low socioeconomic status appeared to be the major factor accountable for the high prevalence of advanced stage cases and anaplastic carcinomas. Iodine deficiency appeared to play a specific role in the increased prevalence of follicular types of thyroid carcinoma.