When is prostate cancer really cancer?

Several investigators have challenged the idea that low-grade cancers are a cause for concern, suggesting that the term cancer should not be applied to these tumors. This article reviews the defining features of cancer, and the diagnostic and prognostic classification systems currently used for prostate cancer. Logical, morphologic, and molecular evidence is presented to show that low-grade prostate cancers are correctly classified as cancer. The authors suggest, however, that 6 out of 10 on an aggressiveness scale is inappropriate for indolent cancer, and that a proposed reinterpretation of Gleason grading categories is a more logical way to address overtreatment.