Detection of tumor cells in bone marrow of patients with primary breast cancer: a prognostic factor for distant metastasis.

PURPOSE: At the time of primary surgery, approximately 90% of all patients with breast cancer are free of metastases, but in the next 5 years almost 50% of them will relapse. We evaluated the significance of the presence of tumor cells in bone marrow of patients with primary breast cancer to investigate their predictive value for relapse. PATIENTS AND METHODS: Two hundred sixty patients with primary breast cancer were examined for tumor cells in bone marrow aspirates taken from six sites of the skeleton. After density centrifugation, cells in interphase were smeared and stained. For the immunocytologic reaction, we used a new monoclonal antibody (2E11) that was reactive with the core protein of the tumor-associated glycoprotein TAG12. TAG12 is secreted by nearly all human breast carcinomas. RESULTS: A significant correlation was found between tumor-cell detection and tumor stage (P < .0001), nodal status (P < .0001), and tumor grading (P = .002). A good relation to progesterone receptor (PR; P = .008) was found, but there was no correlation to estrogen receptor (ER) and menopausal status. Follow-up examinations showed distant metastases in 26 of 211 patients (15%). Twenty-two relapses occurred among the 81 patients with 2E11-positive cells in bone marrow, but only four occurred among the 130 patients without tumor-cell detection. CONCLUSIONS: This study suggests that tumor-cell detection in bone marrow of patients with primary breast carcinoma is a good predictor for all distant relapses (P < .0005, Cox multiple regression analysis) and provides additional information in regard to other prognostic factors. The highest predicting value for distant metastasis results from the combination of nodal status, negative PR, and tumor-cell presence in bone marrow.