Oncotype DX in BRCA-mutated Breast Cancer Patients: Our Experience. A Retrospective Observational Monocentric Study

In the past decades, genetic testing for cancer susceptibility has become essential in breast cancer (BC) management. Up to 10% of BC cases are associated with an inherited mutation in various genes, especially BRCA 1 and BRCA 2. Estrogen receptor (ER) positivity is observed in 22% on BRCA 1 and 77% of BRCA 2 mutation carrier; moreover, other genes are strongly related to ER-positive cancer.

Oncotype DX assay (Genomic Health, Inc, Redwood City, Calif) is a 21 gene panel developed to predict the risk of tumor recurrence in patients with ER-positive and human epidermal growth factor 2 (HER2)- negative BC; nowadays, this test represents a standard of care to guide adjuvant chemotherapy decision recommended in several guidelines. According to Oncotype DX Recurrent Score (RS)® a high RS shows a worse prognosis and predicts chemotherapy benefit in patients with ER-positive HER2-negative BC.

Combining Oncotype DX RS® with other risk factor elements, in particular germline mutations, could help to select patients who would benefit from an appropriate adjuvant therapy.

This retrospective observational study aims to evaluate Oncotype DX RS® distribution in ER-positive HER2-negative BC patients treated from January 2012 to December 2021, focusing on patients harboring mutation in BC-associated genes compared to the general population.

Inclusion criteria

• Age at diagnosis at least 18 years
• Women who underwent breast surgery in OSR
• Patients with ER-positive, HER2-unamplified early-stage BC who underwent the Oncotype DX assay, according to the standard of care.

Exclusion criteria

• Male
• ER negative or HER2 amplified disease
• Patient s who did not undergo breast surgery in OSR
• Patient s who did not undergo the Oncotype Dx assay