Isolated tumor cells in bone marrow three years after diagnosis in disease-free breast cancer patients predict unfavorable clinical outcome.

The aim of the study was to explore the value of analyzing bone marrow (BM) for the presence of isolated tumor cell(s) (ITCs) in disease-free breast cancer patients 3 years after diagnosis. ITCs in BM at operation was found to be an independent prognostic factor in 817 breast cancer patients. Among these, 356 disease-free patients were analyzed with a second BM after 3 years follow-up (median 40 months, SD 3 months, range 29-52). ITC was detected by immunocytochemistry with anticytokeratine antibodies (AE1/AE3). The population consisted of 70% T1 and 72% node-negative patients. ITC in BM was detected in 15%. At a median of 25 months since the second BM aspiration (66 months since diagnosis), 32 patients had developed relapse, 12 local and 20 systemic. Of the patients with ITC in BM, 21% relapsed compared with 7% of the ITC-negative patients (P < 0.001). Ten patients died of breast cancer. Survival analyses showed that ITC in BM predicted reduced distant disease-free survival (DDFS) and breast cancer specific survival (BCSS; P < 0.001, log-rank test). Uni-and multivariate analyses of the prognostic value of N, T, estrogen receptor/progesterone receptor, and BM status, histological grade, vascular invasion, p53-, c-erb-B2-, and cathepsin D expression were performed. BM status was the only independent prognostic factor for both DDFS and BCSS, whereas c-erbB-2 and N status were independent for BCSS and vascular invasion and T status for DDFS. ITC in BM 3 years after diagnosis in disease-free breast cancer patients is an independent prognostic factor. Detection of residual disease by BM analysis at follow-up may unravel insufficient adjuvant treatment. The clinical implications should be further explored.