Recent advances in technologies for the detection of occult metastatic cells in bone marrow of breast cancer patients

Approximately half of breast cancer patients with stage I-III disease will suffer metastatic disease despite resection with tumour-free margins. In 30 -40% of these patients, individual carcinoma cells can already be detected at the time of primary therapy in cytological bone marrow preparations usin g immunocytochemistry. Numerous prospective clinical studies have shown tha t the presence of occult metastatic cells in bone marrow is prognostically relevant to patient survival. Only a few studies failed to do so, thus stim ulating a critical discussion on the methodology and clinical value of bone marrow analysis. The potential for obtaining improved prognostic informati on on patient outcome, for monitoring tumour cell eradication during adjuva nt and palliative systemic therapy, and for specifically targeting tumour b iological therapies are intriguing clinical opportunities that may be affor ded by bone marrow analysis. Standardized and robust methodology is a prere quisite for clinical application of these techniques, however.