EDITORIALS Breast Cancer Prognostic Factors: Evaluation Guidelines

In the present issue of this journal, Thor and colleagues attempt to evaluate heat shock protein 27 (also known as the 27 000-dalton stress response protein or srp-27) measured in tumors from breast cancer patients as a prognostic factor (1). They report significant correlations between srp-27 overexpression and other measured prognostic factors as well as between srp-27 overexpression and a shorter disease-free survival period. However, they state that a multivariate analysis failed to recognize srp-27 expression as a significant independent predictive factor. Before commenting on the Thor paper, it might be useful to consider first the broader problem of how the casual reader should evaluate papers dealing with prognostic factors in breast cancer. The use of prognostic factors to help select breast cancer patients for adjuvant therapy is of considerable concern to the oncology community (2). This need for selection of prognostically less favorable cases is stimulating investigators to identify new and more powerful prognostic factors. Unfortunately, however, this identification process is becoming more confusing because of a lack of guidelines for investigators to use to study new factors and for reviewers and readers to use to evaluate papers on this topic. Listed here are the minimal criteria that must be considered when one is attempting to evaluate a new prognostic factor.