SERUM THYROID PEROXIDASE AUTOANTIBODIES, THYROID VOLUME, AND OUTCOME IN BREAST-CARCINOMA

The prevalence of thyroid peroxidase autoantibodies (TPO.Ab) was asses sed in patients with either breast carcinoma or benign breast disease, and its association with disease outcome in breast carcinoma was stud ied. TPO.Ab were detected by direct RIA in serum from 121/356 (34.0%) of patients with breast carcinoma, compared with 36/194 (18.5%) of con trols (P < 0.001); and in 31/108 (28.7%) with benign breast disease, c ompared with 12/88 (13.6%) of controls (P < 0.05). Survival analysis i n a group of 142 women with breast carcinoma demonstrated that TPO.Ab titres greater than or equal to 0.3 U/mL were associated with a signif icantly better disease-free [relative risk (RR) = 1.84, P < 0.05] and overall survival (RR = 3.46, P < 0.02), compared with those who were T PO.Ab-negative. Better outcome associated with higher TPO.Ab titres wa s confined to those who had thyroid volumes within the intermediate ra nge (10.1-18.8 mL) and did not further enhance the good outcome record ed when volumes were less than or equal to 10.0 mt or > 18.8 mL. Multi variate survival analysis showed that both TPO.Ab and thyroid volume w ere independently associated with prognosis in breast carcinoma and th at RRs for disease-free survival were of a similar order of magnitude to well-established prognostic indices such as axillary nodal status o r tumor size. These findings supply evidence that manifestations of th yroid autoimmunity are associated with a beneficial effect on disease outcome in breast carcinoma and provide the strongest evidence to date of a biological link between breast carcinoma and thyroid disease.