Sensitivity analyses supported the robustness of the analysis. Compared to no testing, the full testing strategy of genetic and genomic testing was more effective at a lower cost or was cost-effective, supporting the goal to increase the survival and the quality-of-life of women with breast cancer along the cancer care continuum.
Recurrence score risk-category discordance is frequent in synchronous bilateral and unilateral multifocal breast cancer and often changes adjuvant chemotherapy recommendations. Reliance on single-lesion testing risks missing clinically relevant genomic heterogeneity. Multilesion testing may be warranted in selected patients to optimize treatment selection.
Prognostic stage significantly influences survival among patients with low RS. RS < 11 alone should not automatically downstage patients to PPS IA; anatomic and other nongenomic factors remain important for prognosis.
In HR+/HER2- breast cancer, tumors with lower HER2 mRNA expression exhibit higher lymphocytic infiltration, suggesting the presence of a distinct immunologically active subset. Oncotype DX single gene scores, particularly HER2, may provide information beyond recurrence risk prediction and help identify patients who may benefit from immune-modulating therapeutic strategies.
Using real-world CGP of tumour tissue and ctDNA, we identified key molecular features associated with endocrine resistance in patients with low RS who later developed metastases. PIK3CA mutation and other ER group-related mutations contributed to the low RS. Tissue CGP provides baseline for interpreting ctDNA, and ctDNA monitoring PIK3CA, TP53, ESR1 and other pathogenic or driver mutations in the early course of low RS cases may represent an excellent non-invasive option for identifying targets and early intervention to prevent disease progression, though a large validation study is needed.