An association between thyroid disease and breast cancer

Abstract

21063 Background: Anecdotal studies and isolated case reports have observed an association of thyroid disease and breast cancer. This purported association remains controversial. We describe a retrospective case-control study on the prevalence of breast cancer in patients with abnormal thyroid function studies. Age-matched subjects served as controls. Methods: We reviewed 6211 cases of abnormal TSH values between 1/04 and 12/05 and determined the number of cases with breast cancer. We compared those data to 3,151 control subjects with normal TSH seen during the same period. We excluded patients with thyroid cancer from the total number of malignancies in both groups because abnormal TSH would be expected to result from its treatment. We also reviewed the ER, PR, her 2 neu status and free thyroxine of patients with breast cancers. Results: Breast cancer rate of 36% of all cancers (37/102) in the abnormal TSH group was significantly higher than that of 18% (14/77) in the normal TSH group. (p = 0.012). Breast cancers in the study group with abnormal thyroid function were more frequently hormone receptor positive (74% vs. 67%) and her 2 neu negative (67% vs. 50%). Conclusions: The data suggest that there is an increased rate of breast cancer in patients with abnormal thyroid function. The trend of hormone receptor positive disease in the abnormal TSH group suggests that the IGF receptor may play an important role in the relationship between thyroid disease and breast cancer. The IGF receptor may be a potential target for therapeutic drug development for breast cancer prevention and management. Further studies are warranted. No significant financial relationships to disclose.