This study examined the relationship between serum thyroid hormone levels and the risk of breast cancer. The study analyzed thyroid hormone and antibody levels in 100 breast cancer patients and 75 control individuals without breast or thyroid disease. The mean values for thyroid hormones (T3, T4) and anti-thyroid peroxidase antibodies were significantly higher in breast cancer patients compared to controls. The results indicate an increased prevalence of autoimmune and non-autoimmune thyroid diseases in breast cancer patients, suggesting that abnormal thyroid gland characteristics may influence breast cancer progression.