The objective of this review was to determine whether there is an association between hyperthyroidism and the risk of developing a breast cancer from the analysis of data in the literature.
Method: The analyzed articles were extracted from the PUBMED database from 2002 to 2017 using the following keywords "hyperthyroidism AND breast cancer" and "thyroid AND breast cancer".
Results: A total of 22 studies were selected, including 8 cohort studies, 12 case-control studies and 2 meta-analyzes. Of these 22 studies, 15 have established a significant epidemiological or biological link between hyperthyroidism and breast cancer. Five of them were particularly interested in Graves' disease, and four demonstrated a positive association between this disease and the onset of breast cancer, especially within three years from the thyropathy diagnosis. These different studies also highlighted the increased risk of breast cancer seen in overweight or postmenopausal women. Contradictions persist over the types of mammary cancers observed and their prognosis.
Conclusion: This review reveals that women with hyperthyroidism appear to have a moderately high risk of breast cancer (RR<2). These data are corroborated by solid physiopathological hypotheses. Regardless of the type of thyropathy responsible for hyperthyroidism, care should be taken to ensure that these patients receive a clinical examination of the breasts on an annual basis and mammographic screening every 2 years from the age of 50 years.
Keywords: Breast cancer; Cancer du sein; Graves’ disease; Hyperthyroidism; Hyperthyroïdie; Maladie de Basedow; Thyroxine; Triiodothyronine.
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