What is the purpose of genetic assay for breast cancer?

From the Guidelines

Genetic assays for breast cancer are primarily used for risk assessment, guiding treatment decisions, and predicting cancer recurrence. These tests are crucial for identifying mutations in genes such as BRCA1 and BRCA2, which are associated with an increased risk of breast cancer, as noted in the U.S. Preventive Services Task Force recommendation statement 1. The main purposes of genetic assays in breast cancer include:

• Identifying individuals with a high risk of developing breast cancer due to genetic mutations
• Guiding treatment decisions for patients already diagnosed with breast cancer
• Predicting the likelihood of cancer recurrence
• Informing preventive measures such as enhanced surveillance, chemoprevention, or risk-reducing surgeries For asymptomatic women with a family history of breast or ovarian cancer, genetic counseling and testing are recommended, as outlined in the study by the U.S. Preventive Services Task Force 1. Key considerations for genetic testing include:
• Family history of breast, ovarian, or other BRCA-related cancers
• Personal history of breast cancer
• Age at diagnosis
• Presence of multiple types of primary cancer in family members
• Use of brief familial risk stratification tools to determine the need for in-depth genetic counseling Genetic assays like Oncotype DX, MammaPrint, and EndoPredict analyze tumor tissue to predict recurrence and guide treatment decisions, although the provided evidence does not specifically discuss these tests, the general principle of genetic testing for guiding treatment is supported by the concept of using genetic information to inform clinical decisions 1.

From the FDA Drug Label

Assessment of HER2 protein overexpression and HER2 gene amplification should be performed using FDA-approved tests specific for breast or gastric cancers by laboratories with demonstrated proficiency The genetic assay for breast cancer, specifically HER2 gene amplification, is used for:

• Patient selection: to select patients for therapy based on an FDA-approved companion diagnostic for a trastuzumab product
• Detection of HER2 protein overexpression: to assess HER2 protein overexpression in tumor specimens
• HER2 gene amplification detection: to detect HER2 gene amplification in tumor specimens, which is essential for determining the appropriateness of trastuzumab treatment 2, 2 Key points:
• The assay should be performed using FDA-approved tests
• The test should be specific for breast cancer
• The laboratory performing the test should have demonstrated proficiency

From the Research

Genetic Assay for Breast Cancer

The genetic assay for breast cancer is used for several purposes, including:

• Precise diagnosis and treatment of breast cancer 3
• Selection of adjuvant therapy and prediction of prognosis for early-stage breast cancer patients 3
• Identification of potentially effective antitumor agents for metastatic breast cancer patients 3
• Targeting unaffected high-risk women for prevention and/or close surveillance 4
• Choosing the best chemotherapy for affected women 4

Benefits of Genetic Testing

Genetic testing for breast cancer has several benefits, including:

• Helping to prevent recurrence of the initial cancer and second primary breast and ovarian cancers 4
• Allowing for tailored treatments, such as with cis-platinum or olaparib, for women with BRCA1 mutations 4
• Identifying somatic genetic alterations in key oncogenes and tumor suppressor genes, which can inform diagnosis, treatment, and resistance mechanisms 5

Genes Associated with Breast Cancer

Several genes are associated with breast cancer, including:

• BRCA1 and BRCA2, which are high-penetrance genes 4, 6, 7
• PTEN, TP53, CHEK2, ATM, BRIP1, PALB2, and RAD51C, which are also associated with breast cancer risk 6, 7
• Other genes, such as those involved in DNA repair, which may be associated with moderate or low breast cancer risk 7