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Clinical Significance Of Axillary Micrometastases In Breast Cancer: How Small Is Too Small?

Diana Stripp, MD

University of Pennsylvania Cancer
Last Modified: May 15, 2001

Presenter: Nora M Hansen
Affiliation: John Wayne Cancer Institute at Saint John's Health Center, Santa Monica, CA

Background:

1. Lymph node metastases are the most significant prognostic indicator for patients with breast cancer.
   a. 15-20% LN ? pts die within 5 yrs
   b. 20-30% LN ? pts recurs > 10 yrs
2. Historically hematoxylin and eosin (H&E) staining has been used to detect lymph node metastases.
3. The emergence of sentinel node mapping (SN) has increased the application of highly sensitive immunohistochemical staining (IHC) for examining nodal tissue. However, the significance of IHC metastases remains unknown.
4. This prospective study was designed to determine the survival impact of IHC metastases.

Materials and Methods:

1. 696 patients underwent SN mapping using lymphazurin blue dye with or without a radioactive colloid.
2. The SN was examined by H&E and IHC if H&E stained negative.
3. The patients were then divided into 4 groups: SN negative (n=425, Group I); SN IHC positive/H&E negative or equivocal (n=56, Group II); SN H&E micrometastases < 2mm (n=76, Group III); SN H&E macrometastases >2mm (n=139,Group IV).

Results:

1. At a median follow-up of 44 months, the size of SN metastases was a significant predictor of DFS (p=0.0001) but not OS (p=0.0520).
2. There was no significant difference in DFS between SN negative patients and SN IHC positive patients (p=0.3775) nor was there a significant difference in OS between these two groups (p=0.6593).

Authors' Conclusions

IHC metastases do not appear to adversely affect prognosis at this time. These results suggest that IHC should not be routinely performed on the SN, nor should treatment decisions be made until results of long-term multicenter trials such as the ACSOG Z0010 study are reported.

Clinical/Scientific Implications:

1. IHC of SLN definietly leads to upstage of pt which affects treatment decisions.
2. From early study, IHC + SLN correlates with 7% + axillary LN.
3. In this cohort pts, IHC + SLN has no impact on the DFS or OS as compared to the pts with IHC- SLN.
4. At this time, IHC of SNL does not have a role in the treatment decision process.