Monoclonal antibody LICR-LON-M8 does not predict the outcome of operable breast cancer

The prognostic value of the monoclonal antibody LICR-LON-M8, which has been shown to detect micrometastatic disease, was evaluated in a prospective, double-blind, clinical study of bone-marrow specimens from patients with operable breast cancer. Four bone-marrow specimens, obtained from each of 50 patients at the time of excision of the primary breast tumour, were examined immunohistochemically, with LICR-LON-M8 as the primary antibody. All of the primary tumour specimens demonstrated positive staining for malignant disease with LICR-LON-M8. The bone-marrow specimens of four patients demonstrated positive staining: three specimens were "suspicious" for malignant cells and one contained definite malignant cells on cytologic examination. This gave a 2% rate of detectable micrometastatic disease at the time the primary tumour was excised. Patient follow-up averaged 21.5 +/- 9.1 months. The test results did not correlate with outcome. A negative test result with LICR-LON-M8 did not imply a better prognosis. The authors conclude that examination of bone-marrow specimens stained with LICR-LON-M8 in patients with operable breast cancer is of no clinical value. Furthermore, the low rate of micrometastases detected is at variance with that reported by others. In view of the natural history of breast cancer, the authors believe that their results were not unexpected and they question the importance of other results.