Molecular markers in Paget disease of the breast

Molecular markers are increasingly being analyzed in tumor specimens because of their relevance to both prognosis and choice of therapy. Paget disease of the breast is an uncommon form of breast cancer, in which molecular markers have not been well characterized. The objective of this study was to investigate the expression of c-erbB-2, p53, Ki-67, Cyclin D1, Bcl-2, estrogen receptors (ER), and progesterone receptors (PR) in mammary Paget disease.

Archival tumor tissues from 14 patients diagnosed between 1990 and 1999 with Paget disease of the breast were analyzed for these molecular markers by using an automated immunohistochemical assay. Both the intraepidermal Paget cells and the underlying carcinoma were assessed for these markers.

The majority of Paget cells were positive for c-erbB-2 (92.9%), Cyclin D1 (100%), and Ki-67 (85.7%), but very few were positive for Bcl-2 (14.3%). p53 was overexpressed in 42.9% of the cases, and only 28.6% were positive for ER and PR. The rate of expression of these biologic markers was similar in both the Paget cells and the underlying intraductal and/or ductal carcinoma cells.

Tumors from patients with Paget disease of the breast were positive for c-erbB-2, Cyclin D1, and Ki-67, molecular markers commonly associated with more aggressive tumor behavior and poorer survival in breast cancer patients. Few of these tumors expressed Bcl-2 or ER and PR, which are generally associated with a better prognosis. Similar expression of these markers in both Paget cells and the underlying carcinoma supports the theory that these cells are the result of an intraepidermal spread of ductal carcinoma.