Do bone marrow micrometastases correlate with sentinel lymph node metastases in breast cancer patients?

Background: Sentinel lymph node biopsies (SLNB) are used to detect axillary metastases as an important prognostic indicator for breast cancer patients. Bone marrow micrometastases (BMM) have also been shown to predict prognosis. This study examines whether SLNB and BMM are associated.

Study Design: A retrospective analysis was performed on 124 stages I to III breast cancer patients treated with mastectomy or lumpectomy, SLNB, and bone marrow aspiration between 1997 and 2003. SLNB were examined for the presence of metastases by hematoxylin and eosin (H&E) stains and also by immunohistochemistry (IHC) for lymph nodes negative by H&E. The kappa statistic was used to evaluate the association (agreement) between SLNB and BMM.

Results: In this study population, 36 patients (29%) had micrometastases detected in their bone marrow, and 51 patients (41%) had positive sentinel lymph nodes. Of the patients with positive BMM (n = 36), 53% (19 of 36) had positive SLNB (14 of 19 by H&E and 5 of 19 by IHC). In patients with negative BMM (n = 88), 36% (32 of 88) had a positive SLNB (27 of 32 by H&E and 5 of 32 by IHC). The kappa statistic and associated 95% confidence interval indicated poor agreement between SLNB and BMM (kappa = 0.15; 95% CI = -0.03, 0.32).

Conclusions: There was poor agreement between axillary metastases and micrometastases detected in the bone marrow. This study suggests that BMM and axillary metastases are not concordant findings in most patients.