Abstract ES5-3: Late recurrence in ER-positive breast cancer

Abstract

Abstract The risk of recurrence in early stage, ER-positive breast cancer patients persists for 15-20+ years after diagnosis, and never declines to zero. Rates of late recurrence can be reduced by extending tamoxifen therapy beyond 5 years, with additional tamoxifen or a switch to an aromatase inhibitor. The benefits of extending aromatase inhibitors beyond 5 years remains unclear. The benefit of extended adjuvant endocrine therapy for the average early stage breast cancer patient is small. Extended therapy can be associated with serious increased risks, including thromboembolic events and endometrial cancer with tamoxifen, and fractures and possibly cardiovascular events with aromatase inhibitors. Quality of life can also be impacted, including vasomotor symptoms, sexual dysfunction, and arthralgias. Determining which patients have high residual risk of recurrence beyond 5 years, and importantly whether additional therapy is likely to mitigate that risk, has been the subject of considerable recent research. Tumor size, nodal status and grade of the primary tumor at the time of diagnosis have been shown to be associated with risk of late recurrence in ER-positive breast cancer. Several multi-parameter molecular biomarker assays performed on the primary tumor are able to separate patients into groups at low and high risk for recurrence beyond 5 years when using retrospective data sets. To date, no specific assay has been felt to have high enough level evidence to recommend inclusion in treatment guidelines or use in decision-making regarding continuing, stopping or switching endocrine therapy. Recent studies have evaluated whether there are better determinants of late risk of recurrence, beyond the biology of the primary tumor, that can be performed years after the original diagnosis. Assays that may predict the presence of dormant tumor cells and late relapse include Circulating Tumor Calls (CTCs), Disseminated Tumor Cells (DTCs) in the bone marrow, and circulating tumor DNA, proteins or metabolites. While early data is promising, further research is needed before incorporating into clinical decision-making. Identifying a biomarker to determine patients most likely to benefit from longer duration endocrine therapy, or additional therapeutic approaches, could help in reducing late relapse as well as minimizing the risk of side effects and overtreatment. Citation Format: Gralow J. Late recurrence in ER-positive breast cancer [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 ES5-3.