Bone marrow micrometastases as a prognostic factor in early breast cancer patients

To assess the prognostic significance of bone marrow micrometastases (BMMM) in patients with early breast cancer.

Cytological and cytochemical assessments of bone marrow aspirates were carried out on 100 patients with early breast cancer. The bone marrow was obtained by trephine biopsy or aspiration from both upper iliac crests during general anesthesia. The median follow-up period after surgery was 72 months. The statistical analysis of the data was carried out using the x(2) test and Kaplan-Meier univariate methodology.

BMMM were found in 28 (28%) of all studied women. Bone metastases were proved in 13 (46.4%) of the 28 cases with BMMM within a period of 21 to 50 months after surgery (median 41.3 months). In the patients without BMMM, disease dissemination was diagnosed in 6 (8.3%) of them. In 3 (4.1%) cases bone metastases were proved, while in the other 3 (4.1%) pulmonary metastases were found. A significant relative risk (RR=11.43) of skeletal metastases occurrence with 95% confidence interval (95% CI) from 3.48 to 36.16 was established in patients with BMMM. Survival analysis of all 100 women showed an average survival period of 6.34 years for 95% of the patients (95% CI 6.20- 6.48). The difference in survival between the 2 groups with or without BMMM was not statistically significant.

1) The information of bone marrow status could be used as an additional prognostic criterion to identify a subgroup of early breast cancer patients with a high risk for development of bone metastases. 2) The detection of BMMM is an additional adverse prognostic factor, irrespective of tumour size and axillary node status and might be used to define the need of preventive therapy to reduce the incidence of bone metastases.