Introduction: Associations between breast cancer and thyroid disease have been reported but no convincing evidence exists regarding the causal role for overt thyroid diseases in breast cancer. In this context, we present the case of a middle-aged female patient with breast cancer and chronic autoimmune thyroiditis in an attempt to establish a correlation between the two disorders.
Case report: A 58-year old non-smoking female was diagnosed and treated for right breast cancer at age of 55. Mammogram and ultrasound pointed out one suspicious mass of the right breast of 2 centimeter. There was no evidence of abnormalities of the left breast on physical exam and radiological examinations.
Core needle biopsy of breast mass revealed ductal carcinoma without infiltrations in surrounding structures. A unilateral mastectomy with sentinel node excision was performed. Radiotherapy and three cycles of chemotherapy were added. One year later, the patient presents marked fatigue, daytime sleepiness and bowel disorders. Thyroid function and autoimmunity profile showed: an increase of thyroid antibodies and hypothyroidism, and hypoechoic pattern on ultrasound, suggesting autoimmune thyroiditis. Therapy with daily levothyroxine was recommended. The subject associated metabolic risk factors as obesity, hypercholesterolemia, and hypertriglyceridemia. Bone assessment found osteoporosis with low 25-hydroxyvitamin D. Hypolipemiant therapy, injectable yearly 5 mg zolendronic acid, calcium and vitamin D supplements were recommended. The patient will be further followed-up by a multidisciplinary team regarding the thyroid, bone and oncologic profile.
Conclusions: There is still controversy regarding the potential correlations between breast cancer and thyroid disease by sharing common cytokine anomalies interactions between thyroid hormone ultraand estrogens in hormonally-responsive tissues. In our patient, the development of autoimmune thyroiditis with hypothyroidism after breast cancer seems incidental. List of abbreviations: TPO = Antithyreoperoxidase antibodies TSH = Thyroid Stimulating Hormone, TgAb= Anti-thyroglobulin antibodies, Free T4 = free levothyroxine, DXA = Dual-Energy X-Ray Absortiometry, BMD = Bone Mineral Density, 25-OHD = 25-hydroxyvitamin D, PTH= Parathyroid Hormone, cm = centimeter
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