P4-09-22: Multicenter Quality Assurance Profile Review of Lobular Breast Carcinomas Versus the 21 Gene Recurrence Score: Assessment of Clinical Relevance.

Abstract

Abstract Introduction The oncotype dx (ODX) 21 gene recurrence score (RS), was intended to predict the 10 year risk of breast cancer recurrence for estrogen receptor positive, lymph node negative disease (NEJM 2004;351:2817–26). The proportions of patients that were reported as low, intermediate and high risk were 51%/22%, 27%. This population of patients was dominated by ductal carcinomas (DCA), with a paucity of classical lobular carcinomas (CLCA), which are ER-rich and low grade histology. To date, there is dearth of data regarding the relationship of the RS and CLCA, and the clinical relevance regarding the ODX RS in CLCA has not been studied. Methods As part of quality assurance review at three institutions, the ODX RS for all CLCA were reviewed in order to determine the perceived clinical relevance of the ODX RS compared to the proportions of RS reported (NEJM 2004;351:2817–26). Results A total of 219 cases of ODX were performed on CLCA. The low/intermediate/high risk profile was 58%/40%/2%. Conclusions (1) The risk profile of ODX for CLCA is very different from the original DCA dominant population previously reported. (2) If the goal of ODX is to identify candidates for chemotherapy, then a high RS is a rare event for CLCA, and as such, the judgment to administer chemotherapy to an individual patient would most likely depend upon factors other than the ODX, because 98 percent of patients are combined low/intermediate risk RS. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-09-22.