Gene expression signatures in older patients with breast cancer: a systematic review

BACKGROUND:Gene expression signatures have emerged to predict prognosis and guide the use of adjuvant therapy in patients with hormone receptor-positive breast cancer. The objective of this systematic review was to evaluate the prognostic and predictive value of commercially available gene expression signatures as a tool in adjuvant treatment decision-making in older patients with breast cancer. METHODS:PubMed, MEDLINE, Embase, Web of Science, Cochrane Library, and Emcare were reviewed for relevant articles published before December 2021. Eligible studies were randomised trials and cohort studies that externally validated commercially available gene expression signatures in patients aged 65 years and older, including studies that presented subanalyses of this age group. Data extraction and risk of bias assessment was performed independently by two investigators. RESULTS:Fifteen studies were included. Most studies investigated Oncotype DX, while results from other gene expression signatures were limited. Several studies underlined the prognostic performance of Oncotype DX and Prosigna Risk of Recurrence in older patients. Moreover, Oncotype DX was predictive for older patients with an intermediate-risk recurrence score; chemotherapy could be spared in both lymph node-positive and lymph node-negative disease. CONCLUSIONS:Prognostic performance has been demonstrated in older patients for several gene expression signatures. However, additional validation in patients with high-risk tumours is needed before gene expression signatures can be implemented in clinical practice as a prediction tool for adjuvant chemotherapy decision-making in the older age group.