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Sentinel node metastases predicted DFS, OS in invasive breast cancer with micrometastases
Increased sentinel node metastasis size led to increased detection of nonsentinal node metastases.
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The size of sentinel node metastases was a significant predictor of eight-year DFS and OS, according to data from a prospective study. Patients with micrometastatic tumor deposits, nanometastases or micrometastases did not have a worse DFS or OS compared with patients who were sentinel node-negative.
Between Jan. 1, 1992, and April 30, 1999, researchers enrolled 790 patients with invasive breast cancer into their study to determine the effects of micrometastases in the sentinel node on survival. Hematoxylin and eosin was used to examine the sentinel node; immunohistochemical staining was performed on negative results.
Using the American Joint Committee on Cancer’s staging criteria, the researchers divided patients into four groups, according to sentinel node metastases size: pN0(i-), no evidence of tumor (n=486); pN0(i+), tumor deposit ≤ 0.2 mm (n=84); pN1mi, tumor deposit more than 0.2 mm but ≤ 2 mm (n=54) and pN1, tumor deposit more than 2 mm (n=166). The researchers used Kaplan-Meier to estimate DFS and OS; they used the log-rank test to determine differences in DFS and OS between patients in different groups.
The researchers reported a relationship between tumor size and the presence of sentinel node metastasis; mean tumor size increased from 1.4 cm in the negative group to 2.2 cm in the isolated tumor cell group, 2.1 cm in the micrometastases group and 2.9 cm in the macrometastases group. An increase in the size of the sentinel node metastasis resulted in an increase in the detection of nonsentinel node metastases: from 4% in the isolated tumor cell group to 19% in the micrometastases group and 59% in the macrometastases group.
Sentinel node metastases was a predictor of eight-year DFS (P < .0001) and OS (P<.001), at a median follow-up of 72.5 months. The researchers reported no difference in eight-year DFS or OS among the negative, isolated tumor cells or micrometastases groups; whereas macrometastases was associated with a significant difference in both DFS and OS at eight years (P<.0001 for both).
According to Thomas B. Julian, MD, associate director at the Breast Care Center at Allegheny General Hospital in Pittsburgh, and author of an accompanying editorial, data from recently accrued, large studies will hopefully provide answers to current questions surrounding the significance of nano- and micrometastatic disease, the predictive significance of menopausal status and the addition of systemic therapy in nano- and micrometastatic disease.
“Perhaps as clinical trials more fully embrace molecular diagnostics used in trials such as TAILORx and MINDACT to better determine predictors of outcome based on primary tumor biology, physicians will be able to apply the resulting data to systemically treat patients in a more selective and effective manner,” he wrote.
Hansen NM. J Clin Oncol. 2009;doi:10.1200/JCO.2008.19.0686