Table 3. Mean age distribution of thyroid cancer in three different periods.

Histological type	Before USI	During USI	After USI
PTC	42.92±12.40	44.28±12.01*	43.47±11.02*
FTC	39.56±12.73	43.61±16.40**	51.90±16.20**
MTC	53.93±11.95	46.56±10.10	48.64±10.83

*, statistically significant (after USI vs. during USI, P<0.001); **, statistically significant (after USI vs. during USI, P<0.01). PTC, papillary thyroid cancer; FTC, follicular thyroid cancer; MTC, medullary thyroid cancer; USI, universal salt iodization.