Abstract
Simple SummaryBreast cancer (BC) is the most prevailing cancer in women worldwide. Amongst the different BC subtypes, human epidermal growth factor receptor 2 (HER2)-positive tumours are characterised by an overexpression of the HER2 membrane receptor. Nowadays, HER2-status assessment relies on immunohistochemical methodologies in the tumour tissue, which could be complemented by novel methodologies to improve the clinical management of these patients. In this regard, liquid biopsy is an easy, rapid, and minimally invasive tool to obtain circulating tumour components from body fluids. Herein, by reviewing the published studies, we aim to decipher the clinical validity of liquid biopsy in both early and metastatic HER2-positive BC.Invasive breast cancer (BC) is the most common cancer in women with a slightly increasing yearly incidence. BC immunohistochemical characterisation is a crucial tool to define the intrinsic nature of each tumour and personalise BC patients’ clinical management. In this regard, the characterisation of human epidermal growth factor receptor 2 (HER2) status guides physicians to treat with therapies tailored to this membrane receptor. Standardly, a tumour solid biopsy is therefore required, which is an invasive procedure and has difficulties to provide the complete molecular picture of the tumour. To complement these standard-of-care approaches, liquid biopsy is a validated methodology to obtain circulating tumour components such as circulating tumour DNA (ctDNA) and circulating tumour cells (CTCs) from body fluids in an easy-to-perform minimal-invasive manner. However, its clinical validity in cancer is still to be demonstrated. This review focusses on the utilisation of both ctDNA and CTCs in early and metastatic HER2-positive BC tumours. We discuss recently published studies deciphering the capacity of liquid biopsy to determine the response to neoadjuvant and adjuvant therapies as well as to predict patients’ outcomes.
Highlights
Breast cancer (BC) is the most common cancer among women worldwide and one of the major causes of cancer-related mortality in women [1]
breast cancer (BC) can spread through distant metastases, which could worsen the 5-year survival rate to as low as 28% [4], and therapeutic strategies in these cases are mostly palliative in nature
The main obstacle for designing effective treatment approaches in BC is the complex heterogeneity of these tumours [5]
Summary
Breast cancer (BC) is the most common cancer among women worldwide and one of the major causes of cancer-related mortality in women [1]. With peak incidence between 35 and 75 years, most cases develop sporadically, and less than 10% of them are hereditary due to germline mutations [2]. The clinical management of BC has improved remarkably in the last decades by advancements in surgery and (neo)adjuvant therapies in early stages. These have made it possible to achieve a 5 year overall survival rate above 90% [3]. BC can spread through distant metastases, which could worsen the 5-year survival rate to as low as 28% [4], and therapeutic strategies in these cases are mostly palliative in nature.
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