Factors connected with the female sex seem to play an important role in differentiated thyroid cancer

Aim. The aim of the study was to analyze whether female sex hormones and other factors connected with the female sex could increase the risk of differentiated thyroid cancer (DTC). Material and methods. Ninety-nine patients with a mean age +/- SD of 40.5 +/- 5.9 years with DTC and 51 healthy women with a mean age of 36.52 +/- 8.3 years were examined. Gynecological and obstetric histories were taken and serum estradiol and progesterone levels were analyzed in all women. Results. Patients with DTC had more frequent menstrual cycle disturbances, used hormone-containing medicines more frequently, were mulitiparous more frequently, had spontaneous miscarriages more frequently, and their duration of lactation was significantly shorter than in controls. The mean serum estradiol level +/- SD in women with DTC was significantly higher than that in the controls, in the follicular phase 193.74 +/- 66.31 vs. 157.63 +/- 42.88 pmol/L and in the luteal phase 519 +/- 176.9 vs. 369 +/- 71.49 pmol/L. The mean serum progesterone level +/- SD was higher in the controls than in DTC patients in the follicular phase: 2.11 +/- 0.70 vs. 1.38 +/- 0.56 nmol/L; in the luteal phase: 20.95 +/- 17.46 vs. 17.31 +/- 12.28 nmol/L. Conclusions. The results of these studies imply that estrogens may at least modify the proliferation of thyroid cancer cells. The sex hormones probably intensify the actions of other carcinogens as well.