Micrometastases to bone marrow in primary breast cancer patients – A long time follow up in 1256 patients

The detection of epithelial cells in the bone marrow (BM) of primary breast cancer (BC) patients may be the missing link between the local disease and the development of secondary metastases to bone or other sites (micrometastasis. The detection of those cells was used in several studies to assess the prognosis of BC patients and may define the therapeutic setting of new therapies.

In this study we compared 622 BC patients with (MUC-antibody used; group BM(+)) against 634 patients without detected epithelial cells in BM (group BM(-)) regarding their prognosis. Patients were operated at the Dept. of gynecology of the University Clinics of Heidelberg/ Germany between 1990 and 2000. Mean follow up time was 83±39 months. Primary clinical and pathological stage of disease was similar in both groups.

22.4% of the patients with micrometastases developed bone metastases in comparison to 13.6% of the patients without (to other sites 14.8% respective 7.3%). Overall survival was significantly lower in the micrometastatic group (p<0.001). 15.3% of KM(+) in comparison to 27.8% (KM(+)) died because of BC, 10 year survival rate was 81.1% in comparison to 66.0%. The RR for death because of BC was 2.11 (95%KI: 1.64, 2.72) for KM(+) patients. RR adjusted for tumor size, nodalstatus, and grading was 1.62 (1.25, 2.10).

Our analysis confirm the results of our earlier studies as well as those of other groups but with the longest follow up time period ever published. The detection of epithelial cells in the BM of BC patients is an independent prognostic factor and should have an impact to the therapeutical setting.