Prognostic factors for well-differentiated thyroid cancer in an endemic area.

A retrospective analysis of 215 differentiated thyroid cancers was undertaken to identify the various prognostic variables. There were 132 papillary and 83 follicular cancers; both histologic types occurred at an earlier age, with a male to female ratio of 1: 1.1 (signifies near parity in both sexes, in contrast to marked female preponderance in most of the reports and amongst benign thyroid disorders). There was a significant difference in the size of the primary tumours; 60/132 (45%) of papillary and 30/83 (36%) of follicular cancers were early T0-1 lesions and 20 (15%) papillary and 24 (29%) follicular cancers were advanced T3 lesions. Age did not affect the size of the primary tumour. Regional lymph node and pulmonary metastases were common in both types of cancer while distant metastases occurred more frequently in follicular cancers (p < 0.005). Following surgery, contralateral lobe recurrence in the remaining lobe was more common in the follicular cancer group, while loco-regional recurrence after near-total thyroidectomy was more frequent in the papillary cancer group (p > 0.05). Mortality in 26/132 (20%) papillary and 28/83 (34%) follicular cancer patients was high in both groups, but significantly higher in the follicular cancer group (p < 0.05). Although mortality among patients with papillary cancer was higher in patients older than 40 years of age (p < 0.05), age did not affect survival in patients with follicular cancer. Gender did not affect survival in either group. The extent of the disease at presentation was the most important determinant of survival, with mortality significantly higher among patients with T3N3M1 lesions (p < 0.001).