Molecular Profiling in Young (<50 Years of Age) Patients With Metastatic Breast Cancer

Overview

Breast cancer is the most common cancer in women worldwide, especially in developed countries. In developing countries, including South Korea, the incidence and mortality rate of breast cancer is rapidly increasing. One of the most important characteristics of breast cancer in South Korea, as well as in other Asian countries, is the younger onset of disease compared to Western. Medical treatment of breast cancer is evolving rapidly, incorporating immune checkpoint blockades and molecularly targeted agents. However, data and knowledge are still limited in terms of molecular characteristics of Asian breast cancer, compared to that of Western countries, and this remains a major hurdle for drug development in Asian breast cancer patients. The primary objective of this study is to elucidate the genetic characteristic of young (\<50 years of age) Korean patients with metastatic breast cancer using FoundationOne CDx.

Secondary Objective(s): 1. To evaluate the prognostic and predictive role of tumor mutation burden. 2. To reveal the correlation between genetic characteristics and immunohistochemical expression of selected proteins (including DNA damage repair (DDR) molecules and various immune modulating molecules including PD-L1, PD-1, IDO, and OX40). 3. Compare molecular characteristics of breast cancer according to age groups (\<35 years vs. 35-50 years). 4. To offer genomic profiling guided therapy to patients as early as possible (preferably, 1st- or 2nd-line of treatment). In addition, to explore how genomic profiling guided therapy could improve patient outcome as an ad-hoc if sufficient number of patients can be followed up (compared to historic data).