Bone marrow micrometastases in early breast cancer-30-year outcome.

Background: Micrometastases in bone marrow of women with early breast cancer were first identified immunocytochemically in the 1980s. We report on the original cohort of women with a median follow-up of 30 years.
Patients and Methods: In total, 350 women with primary breast cancer had eight bone marrow aspirates examined with antibody to epithelial membrane antigen. Data on long-term mortality were obtained via record linkage to death certification.
Results: At a 30-year median follow-up, 79 out of 89 (89%) patients with micrometastases have died compared with 202 out of 261 (77%) without (hazard ratio=1.46 (95% CI 1.12-1.90), P=0.0043). Most marked effect of micrometastases on overall survival (OS) was seen in patients aged ⩽ 50 at surgery (N=97, P=0.012), and on all patients within 10 years of diagnosis. In multivariable analyses, the presence of micrometastases was no longer a statistically significant prognostic factor.
Conclusions: Bone marrow micrometastases are predictive for OS, particularly in the first decade and in younger patients.