S phase index and ploidy prognostic markers in node negative breast cancer: information for nurses

The National Cancer Institute (NCI) issued a Clinical Alert on node negative breast cancer in May 1988. Based on findings of clinical studies, the Alert advised that adjuvant hormonal or cytotoxic chemotherapy could have a meaningful impact on the natural history of patients with node negative breast cancer. Prior to the Alert, the majority of women diagnosed with node negative breast cancer did not receive adjuvant treatment. To determine which patients with node negative breast cancer can potentially benefit from adjuvant treatment, a number of biological variables need to be considered: menopausal status, tumor size, histopathology, nuclear grade, and steroid hormone receptor status. Recently two new prognostic indicators--S phase index (SPI) and ploidy--have been incorporated into the clinical setting. This article explains these indicators and provides patient education information.