Sonographic detection of thyroid cancer in breast cancer patients

The purpose of our study was to analyze the incidence of incidental thyroid cancers which were detected by simultaneous sonographic examination of breast and thyroid glands. Between January 2001 and March 2004, 518 patients were diagnosed with breast cancer after modified radical mastectomy (n=369) or breast conserving surgery (n=149). We screened thyroid glands when we examined breast for diagnosis and follow-up after surgery. If we found the sonographic finding of suspicious for malignancy in thyroid, we immediately performed ultrasound-guided fine needle aspiration biopsy (FNAB). Forty-two cases showed suspicious sonographic findings and of those, 18 cases (42.9%) were determined to have suspicious malignant cytology by ultrasound guided FNAB. Among 518 breast cancers, total 13 cases (2.5%) were diagnosed with papillary carcinoma after thyroidectomy. The mean longest diameter of the thyroid masses was 9.9 mm (range 1-30 mm). Six cases (6/13, 46.2%) were diagnosed as simultaneous breast and thyroid cancers, and the rest of the thyroid cancers were detected after 6 to 33 months (mean 16.5 months) after surgery. In conclusion, the patients with breast cancer had a high incidence (2.5%) of thyroid cancer. Sonographic screening is useful for the early detection of thyroid cancer.