IMPACT OF PREGNANCY ON PROGNOSIS OF DIFFERENTIATED THYROID CANCER: CLINICAL AND MOLECULAR FEATURES.

OBJECTIVE: Differentiated Thyroid Cancer (DTC) commonly occurs in women of child-bearing age and represents the second most frequent tumor diagnosed during pregnancy only behind breast cancer. It is possible that associated physiological changes could favour tumor development and growth. However, few data are available about the outcome of DTC related to pregnancy, leading to conflicting results. Methods: 340 patients with DTC <45 years old were retrospectively studied. Patients were divided into three groups according to the time of tumor diagnosis respect of pregnancy. Group 1: diagnosis of DTC at least 2 years after delivery, Group 2: diagnosis during pregnancy or within the second year after delivery, Group 3: nulliparous patients at the time of diagnosis. We evaluated clinical outcome and immunohistochemical expression of estrogen receptor α (ERα), estrogen receptor β (ERβ), progesterone receptor (PGR) and aromatase. We also analysed the gene expression of NIS and the prevalence of BRAF V600E mutations. Results: Persistence/recurrence of disease was significantly higher in group 2 patients than control groups (p: 0,023). No significant differences were observed in other clinical parameters. Furthermore no difference among the groups were recorded about ER pattern, NIS expression and BRAF mutations. Conclusions: Persistence/recurrence of DTC is significantly higher in pregnant patients, suggesting that pregnancy could really exert a negative prognostic role in patients with DTC. The underlying mechanisms are not yet clarified and further studies are required. Our results suggest that a more careful follow up is needed when diagnosis of DTC occurs during pregnancy or shortly after.