Abstract ES5-2: Clinical and molecular profiles to identify who is at risk?

Abstract

Abstract The persistent risk of recurrence from ER-positive primary breast cancer has been known for many years. It was recently described in detail and in relation to baseline clinicopathologic factors in a meta-analysis by the EBCTCG. This involved nearly 63,000 patients that had been prescribed 5 years of endocrine therapy and had reached the end of that time recurrence-free (Pan et al, NEJM, 2017, 377, 1836). Among other things this revealed that even among patients with T1N0 disease 13% had a distant recurrence between years 5 and 20. Our group have previously created a Clinical Treatment Score (CTS) from nodal status, tumor size, grade, age and type of adjuvant endocrine treatment and validated this for estimating risk of distant recurrence from the time of diagnosis. Drawing on a training dataset of 4,735 patients from the ATAC trial and a validation set of 6,711 patients from the BIG1-98 trial we created the CTS5, a prognostic score of risk from year 5, that features the same factors as CTS other than type of endocrine treatment (Dowsett et al, JCO, 2018, 36, 1941). Of note, only 4/304 patients with one to three positive nodes that were categorized as low risk in the validation set had a distant recurrence between years 5 and 10. The CTS5 calculator can be accessed online at www.cts5-calculator.com. There are several commercially available molecular profiles that estimate the risk of recurrence over years 0-10 after diagnosis in endocrine-treated primary breast cancer. In the TransATAC study some of these, including the EPClin and PAM50-ROR, show similar prognostic information over years 5-10 (after 5 years of endocrine therapy) as they do over years 0-5 (during endocrine therapy). In contrast, while the Oncotype Recurrence Score (RS) showed similar prognostic information to EPClin and PAM50-ROR in years 0-5 its performance in years 5-10 was substantially worse. Examination of the time-dependent prognostic relationship of each of the individual genes and modules in the RS showed that those patients with higher ER signaling had good prognosis before year 5 but poorer after year 5, suggesting that the cessation of endocrine therapy may lead to this poorer post-5 year outcome (Dowsett et al Clin Cancer Res, 2015, 21, 2763). A broad-based assessment of gene expression in the TransATAC sample set found that there was limited potential to identify a prognostic profile that performed substantially better after 5 years (Buus et al, Breast Cancer Res, 2018, 20, 103). One test, the 7-gene Breast Cancer Index, has reported on a relatively small sample set that it can predict the benefit or not from extended adjuvant endocrine therapy. Further validation studies of this are warranted as well as other tests that provide the same predictive information. Citation Format: Dowsett M. Clinical and molecular profiles to identify who is at risk? [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr ES5-2.