Clinico-pathologic Characteristics of the Primary Thyroid Cancer in Patients with Breast Cancer

Abstract

Background: Both thyroid and breast cancers occur more frequently in women than in men. Some suggest that estrogen plays a role in the tumorigenesis of both cancers. The aim of this study was to identify the prevalence and clinico-pathologic characteristics of primary thyroid cancer in patients with breast cancer. Methods: We retrospectively obtained clinical and pathologic data for 112 patients diagnosed with both thyroid and breast cancer from a single center. Patients with thyroid cancer were grouped according to the chronological sequence of tumor diagnosis. When thyroid and breast cancers were diagnosed within 12 months of each other, they were considered to have been diagnosed simultaneously. Female patients who had only papillary thyroid cancer were used as a historic control. Results: Between 1994 and 2008, 7,827 patients at our hospital were diagnosed with breast cancer and 6,571 patients with thyroid cancer. There were 112 patients who had both thyroid and breast cancer. All thyroid cancers (111/112) except one hurthle cell cancer were papillary thyroid cancers. Average tumor size of thyroid cancer cases diagnosed 1) after or 2) simultaneously with the diagnosis of breast cancer was significantly lower than that for 3) thyroid cancer cases found before breast cancer diagnosis or 4) historical controls with papillary thyroid cancer [sizes (in cm), respectively, were: 1) 0.9 ± 0.6 2) 0.9 ± 0.5 vs 3) 1.4 ± 0.9 4) 1.4 ± 1.1, P < 0.05]. No patients had distant metastases and there were no statistically significant differences in known risk factors for recurrence and survival of patients with thyroid cancer. Conclusion: Thyroid cancer is the most common second primary malignancy in patients with breast cancer and most of them are papillary thyroid cancers. There are no differences in risk factors for tumor recurrence and patient survival compared with those with conventional papillary thyroid cancer except for differences in tumor size. These difference in size may reflect an increase in medical surveillance in patients after they are diagnosed with breast cancer. (J Korean Endocr Soc 24:240~246, 2009) ꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏ