PROLIFERATION INDEX AS A PROGNOSTIC MARKER IN BREAST-CANCER

Background. The proliferative activity of tumors has been extensively investigated with different approaches, among which the use of the mon oclonal antibody Ki-67 represents an easy and reliable means of assess ing cell proliferation. In this study, the proliferative activity of 1 29 primary breast cancers was investigated, and the results were relat ed to prognosis. Methods. Tumor samples, obtained from 129 patients wh o underwent surgery between january 1987 and December 1988, were proce ssed for staining by an immunohistochemical procedure (avidin-biotin c omplex). The median time of observation was 42 months (range, 31-55 mo nths). Life-table analysis (Mantel-Cox) was used to assess the probabi lity of disease-free survival (DFS) and overall survival (OS). Results . Tumors with high Ki-67 proliferation indices (> 20%) were associated with a higher 4-year probability of relapse of disease (55.3% versus 79.1%; P = 0.003) and death (71% versus 95.6%; P = 0.00005) when compa red with tumors with low Ki-67 values. In addition, this proliferative parameter maintained its prognostic significance when the patients we re stratified according to lymph node involvement, menopausal status, and nuclear estrogen receptor content. Conclusions. Tumor proliferativ e activity as evaluated by the monoclonal antibody Ki-67 seems to be a n effective indicator of prognosis in breast cancer for DFS and OS.