Long-term follow-up study of a prospective multicenter sentinel node trial: molecular detection of breast cancer sentinel node metastases.

BACKGROUND: This prospective multicenter sentinel lymph node (SLN) trial investigated whether molecular analysis would improve the detection of SLN metastases and their prognostic value. We report mammaglobin quantitative real-time polymerase chain reaction (qRT-PCR) results and clinical outcome for 547 patients (mean follow-up 7 years). METHODS: Breast cancer patients (excluding stage IV disease or palpable nodes) were enrolled from 1996 to 2005 at 16 institutional review board-approved sites. Alternate 2-mm serial sections of each SLN were examined by hematoxylin and eosin staining with or without immunohistochemistry at multiple levels or blinded and assayed by Taqman qRT-PCR according to previously established thresholds. RESULTS: Mammaglobin remains a highly specific (99%), sensitive (97% primary tumor; 82% N1 SLN) marker for breast cancer. Mammaglobin SLN expression was associated with other prognostic factors, was detected in most patients with distant recurrence (48 of 79; 61%), and was associated with decreased recurrence-free survival (log rank P < 0.0001). Molecular analysis upstaged 13% (52 of 394) node-negative (N0) patients who exhibited a significantly lower distant recurrence-free survival compared to node-negative, PCR-negative patients (80 vs. 91%; P < 0.04). N0 patients with PCR-positive SLN were 3.4 times more likely to experience relapse than PCR-negative patients (odds ratio 3.4; 95% confidence interval 1.6-7.1; P = 0.001). However, molecular staging failed to predict most of the N0 patient recurrences (25 of 34) and was not a statistically significant independent predictor of distant recurrence. CONCLUSIONS: To our knowledge, these data are the first to prospectively compare PCR detection of SLN metastases with long-term outcome in breast cancer patients. Molecular staging of SLN detected clinically significant disease missed by standard pathology. Further refinement and optimization of molecular staging is indicated to improve clinical utility.

Prognostic implications of isolated tumor cells and micrometastases in sentinel nodes of patients with invasive breast cancer: 10-year analysis of patients enrolled in the prospective East Carolina University/Anne Arundel Medical Center Sentinel Node Multicenter Study.

BACKGROUND: Sentinel lymph node biopsy (SLNB) is a more sensitive and accurate nodal staging procedure than axillary lymph node dissection (ALND). Because of increased pathologic evaluation in the sentinel node era, more nodal micrometastases (MIC) (> 0.2 mm to 2 mm) and isolated tumor cells (ITC; < or = 0.2 mm) have been identified. We present the 10-year analysis of our prospective SLN study, focusing on regional axillary node status and distant metastases in patients with nodal ITC and MIC. STUDY DESIGN: From 1996 to 2005, breast cancer patients were enrolled in an Institutional Review Board-approved, multicenter study. SLNs were examined at multiple levels by hematoxylin and eosin; most (85%) hematoxylin and eosin-negative SLNs were also examined by cytokeratin immunohistochemistry. Data from 1,259 patients with invasive breast cancer and in whom an SLN was found were reviewed for this analysis. RESULTS: Of the 1,259 patients, 893 (71%) had negative SLNs, 25 (2%) had ITCs, 57 (5%) had MIC, and 284 (23%) had positive SLNs. None of the 13 patients with ITCs who underwent an ALND had additional positive nodes, compared with 27% (11 of 41) of patients with MIC. At a mean followup of 4.9 years, the distant recurrence rates for SLN-negative, ITC, MIC, and SLN-positive groups were 6%, 8%, 14%, and 21%, respectively. The presence of MIC in the SLN was associated with a significantly shorter disease-free interval than was SLN negativity (p < 0.02 by Cox regression model). CONCLUSIONS: This prospective breast cancer study found that sentinel node MIC, but not ITCs, were associated with additional positive nodes and with distant recurrence. These data suggest that ALND may be unnecessary in patients with ITCs. But ALND and more aggressive adjuvant therapy should be considered in patients with SLN micrometastases.

Identification and characterization of optimal gene expression markers for detection of breast cancer metastasis.

Sentinel lymph node (SLN) status is highly predictive of overall axillary lymph node involvement in breast cancer. Historically, SLN-positive patients have undergone axillary lymph node dissection in a second surgery. Intraoperative SLN analysis could reduce the cost and complications of a second surgery; however, existing histopathological methods lack standardization and exhibit poor sensitivity. Rapid molecular methods may lead to improved intraoperative diagnosis of SLN metastasis. In this study, we used a genome-wide gene expression analysis of breast and other tissues to identify seven putative markers for detecting breast cancer metastasis. We assessed the utility of these markers for identifying clinically actionable metastases in lymph nodes through reverse transcriptase-polymerase chain reaction analysis of SLNs from 254 breast cancer patients. Polymerase chain reaction signals were compared to pathology on a per-patient basis. The optimal two-gene combination, mammaglobin and cytokeratin 19, detected clinically actionable metastasis in breast SLNs with 90% sensitivity and 94% specificity. Application of stringent criteria for identifying presumptive hematoxylin- and eosin-positive samples increased sensitivity and specificity to 91 and 97%, respectively. This study represents the first comprehensive demonstration of the utility of gene expression markers for detecting clinically actionable breast metastases. An intraoperative molecular assay using these markers has the potential to significantly reduce second surgeries for patients undergoing SLN dissection.