Bone Marrow Micrometastasis in Breast Cancer

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Summary and Comment

Bone Marrow Micrometastasis in Breast Cancer

This study provides convincing evidence that bone marrow micrometastases have prognostic significance.

Bone marrow micrometastasis — which can be detected by immunocytochemical staining of bone marrow aspirates — has prognostic significance in breast cancer patients who have no other evidence of distant metastasis. To further explore the predictive value of bone marrow micrometastasis, these researchers (several of whom have some financial interests in companies involved in immunocytochemical staining) pooled data from nine previously published studies involving 4703 patients with stage I, II, or III breast cancer. Bone marrow micrometastases were identified in 31% of patients at the time of initial diagnoses of breast cancer.

During a median follow-up of 5 years, breast cancer recurred (usually as distant, clinically evident metastases) in 25% of patients. In multivariable analyses that controlled for tumor size, tumor grade, lymph-node metastasis, and hormone-receptor positivity, bone marrow micrometastasis independently predicted a significant, nearly twofold, increase in risk for death from breast cancer. Even among low-risk patients (i.e., those with tumors $≤$ 2 cm and negative lymph nodes), bone marrow micrometastasis predicted lower breast-cancer–specific survival, regardless of whether the patient received adjuvant systemic therapy.

Comment: These findings provide convincing evidence that bone marrow micrometastases have prognostic significance in patients with breast cancer, independent of lymph-node involvement and other classic prognostic indicators. This observation might be useful in planning future clinical trials of adjuvant systemic therapy for patients with early breast cancer.

— Allan S. Brett, MD

Published in Journal Watch General Medicine August 30, 2005