Clinical progression of breast cancer malignant behavior: what to expect and when to expect it.

Seemingly localized breast cancer is a heterogeneous mix of truly localized cancers and cancers with occult metastases. Our purpose is to determine the parameters of metastatic proclivity for the different clinical presentations of operable breast cancer and to present quantitative prognostic information useful to both doctors and patients. A series of regionally treated breast cancer patients was analyzed to determine the likelihood and time of the appearance of clinical metastases for different clinical subgroups. Patients operated on at the University of Chicago from 1927 to 1987 for clinically regionally localized breast cancer, who received no systemic therapy as a part of their initial treatment, were included. Overall survival and distant disease-free survival in this mature series are analyzed. Metastagenicity, the metastatic proclivity of a tumor, increases with both tumor size and nodal involvement. This is also true for virulence, which is the rate at which these metastases appear. Each clinical group has a cured population, even those with extensive nodal involvement. A table provides a tool for determining the proportion of risk expended in each clinical group as a function of the distant disease-free survival. Whereas the likelihood of metastasis increases with tumor size and nodal involvement, the time to their appearance decreases. Breast cancer metastagenicity and virulence are heterogeneous even within clinically similar groups of operable breast cancer patients. Tumor progression is correlated with increasing tumor size and nodal involvement. Markers are needed to identify individual tumor virulence and metastagenicity.