Determination of placental ferritin-positive peripheral lymphocytes in early stages of breast cancer.

"Ferritin-blocked lymphocytes" or placental ferritin (PLF) -positive T cells have repeatedly been described in the circulation of patients with female breast cancer. Since a monoclonal antibody directed against PLF became available, a study was performed to evaluate its usefulness in an easily reproducible system. One hundred patients with controversial or highly suspicious findings on mammography who subsequently underwent operation entered this trial. Sixty-one healthy blood donors served as controls. Patients with early (lymph-node negative) stages of breast cancer (in situ and T1N0 tumors) revealed significantly higher numbers of PLF-positive cells (9.00% +/- 4.5% and 6.21% +/- 3.4%) as compared with controls or patients with benign lumps (p < 0.001). Patients with negative lymph nodes differed significantly from node-positive patients (9.79% versus 2.55%; p < 0.001), whereas no difference as related to menopausal and estrogen-receptor status was observed. In order to define the sensitivity and specificity of this test, we analyzed four different cutoff levels (3%, 4%, 5%, and 6% of PLF-positive T cells). At a level of PLF-positive lymphocyte cells of 4%, 94% of cancer patients with stage T1N0 disease or ductal carcinoma in situ, 5% of patients with benign lumps, and 7% of healthy controls were identified. Furthermore, 88% of all lymph node-negative cancer patients had more than 4% positive cells, compared with only 25% in patients with axillary node involvement. The fact that more than 90% of all patients with in situ carcinomas and patients with stage T1N0 cancer had values above 4% offers promising aspects for this method to be used to complement mammography in the early detection of breast cancer.