Abstract
Introduction: Next-generation sequencing (NGS) is commonly used in clinical practice to decide treatment based on genomic information. This study was performed to optimize the proportion of actionable gene profiling and treatment based on genetic alterations in breast cancer at one of the cancer centers in Japan. Methods: Patients with breast cancer who reported NGS results at one of the cancer centers in Japan from August 2019 to December 2023 were retrospectively investigated by reviewing their electronic medical records. Patients were examined using the OncoGuide™ NCC Oncopanel System, FoundationOne® CDx, or FoundationOne® Liquid CDx. The evidence levels for drug recommendation were added for each gene alteration according to the guidelines from three Japanese oncology-related societies. “Actionable alterations” were those at evidence levels A–D, including high microsatellite instability and high tumor mutation burden status. “Patients with recommended drug” (approved, investigational, and off-label drugs) were defined as those who were selected by the Molecular Tumor Board. Results: Of the 106 patients, 54 were tested using the NCC Oncopanel System and 50 using FoundationOne CDx. The most frequent alterations were TP53 mutations (52.8%) and PIK3CA mutations (31.1%). Of the 56 patients (52.8%) with recommended drugs, 11 (10.4%) received genome-matched therapy and only three (2.8%) participated in clinical trials. The most common reason for not receiving genome-matched therapy was patient refusal for personal reasons, although clinical trials were available (18 patients). Conclusion: The top reasons for patients not receiving the recommended genome-matched therapy were factors related to the patient, including a number of prior treatments higher than what was allowed by the eligibility criteria of the clinical trials, and poor physical condition. Most patients received four or more regimens of cytotoxic chemotherapy before NGS. NGS is only available at the late phase of treatment in Japan, which would constitute a problem for the treatment of breast cancer.
