Isolated Tumor Cells, Micrometastases in Sentinel Nodes Fail to Affect Outcomes

December 17, 2007

Breast cancer patients with isolated tumor cells or micrometastases in sentinel nodes do not have poorer disease-free or overall survival than their counterparts with negative sentinel nodes, researchers reported at the SABCS (abstract 52).

Breast cancer patients with isolated tumor cells or micrometastases in sentinel nodes do not have poorer disease-free or overall survival than their counterparts with negative sentinel nodes, researchers reported at the SABCS (abstract 52).

Nora M. Hansen, MD
Photo Courtesy SABCS/Todd Buchanan 2007

"The emergence of sentinel node biopsy has led to an increase in the detection of metastasis by allowing for a more focused histopathologic examination of the sentinel node," said lead author Nora M. Hansen, MD, of the John Wayne Cancer Institute. "It increases the detection of smaller tumor deposits; however, we don't really know the significance of these tumor deposits." In the prospective study, 790 patients with breast cancer underwent a sentinel node procedure with blue dye alone or in combination with isotope. Sentinel nodes were evaluated by H&E and, if negative according to that method, by immunohistochemistry. Overall, 62% of patients had negative sentinel nodes; 11% had isolated tumor cells (immunohistochemically detected deposits measuring <0.2 mm); 7% had micrometastases (deposits measuring 0.2 to 2 mm); and 21% had macrometastases. In a univariate analysis conducted after a median follow-up of 74 months, both disease-free survival and overall survival rates were significantly associated with the size of sentinel node metastases, histologic differentiation, stage, and tumor size. Disease-free survival was also associated with HER2 status and S phase, and overall survival was also associated with age. A multivariate analysis found that patients had significantly poorer disease-free survival rates if they had macrometastases vs smaller metastases in sentinel nodes, Dr. Hansen said. The 8-year rate was about 96%, 98%, 92%, and 83% in patients with negative nodes, isolated tumor cells, micrometastases, and macrometastases, respectively. Findings were similar for distant disease-free survival, with respective 8-year rates for that outcome of 98%, 100%, 94%, and 88%. Patients had poorer overall survival in multivariate analysis if they had macrometastases in sentinel nodes compared with smaller metastases, with 8-year rates of overall survival of about 97%, 100%, 94%, and 88%, respectively. "Isolated tumor cell metastases and micrometastases do not adversely affect disease-free survival, distant disease-free survival, or overall survival ... in this group of patients undergoing sentinel node biopsy," Dr. Hansen said. Physicians knew about the presence of these metastases, however, and that may have led to more aggressive treatment that, in turn, affected outcomes, she said. Therefore, the investigators have undertaken a similar study, the ACSOG Z0010 study, in which patients and physicians are blinded to the immunohistochemical findings in lymph nodes.

Disclosures:

The author(s) have no significant financial interest or other relationship with the manufacturers of any products or providers of any service mentioned in this article.