Genetic testing for breast cancer

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Breast cancer

Approximately every 10th women will have breast cancer throughout life. The proportion of all women with breast cancer that may have a germline mutation in the BRCA1 and BRCA2 genes is between 5% and 10%. The most prevalent type of breast cancer is invasive ductal carcinoma.

60-70% of breast cancers have receptors of estrogen and/or progesterone, that’s why are called «hormone receptor positive».

One fifth of breast cancers occurred due to changes in a gene called human epidermal growth factor receptor 2 (ERBB2, HER2). «HER2 positive» cancers have many copies of the HER2 gene (HER2 amplification) or overexpression of the HER2 protein.

Types of breast cancer that do not express ER, PR, and HER2 are refferred to as «triple negative». Its proportion is about one fifth of invasive breast cancers. Triple-negative breast cancer appears more frequently among younger women and those ones with a mutation in the BRCA1 gene.

Target therapy is a medicine aimed at certain molecules/proteins on the surface of cancer cells or inside, resulting in prevention of the growth and spread of cancer cells without a damage to healthy cells.

One target doesn’t fit all types of cancer. Genetic testing are used to clear up the most effective therapy. Plenty of clinical studies are being conducted constantly.

About the genetic testing for breast cancer

An NGS-based analysis that comprises genes focused on the clinical use of approved targeted medicine for NSCLC and agents from prospective clinical trials.

Changes in these genes result in tumor development and are used as diagnostic, prognostic, and predictive markers of cancer.

The assay identifies:

hotspots (SNV/indels)
copy number variations (CNV)
chromosomal aberrations (gene fusions)

Hotspots (SNV/indels)

8 genes

AKT1

ERBB2

ERBB3

FGFR2

FGFR3

KRAS

NRAS

PIK3CA

Copy number variations (CNV)

9 genes

CCND1

ERBB2

FGFR1

FGFR2

FGFR3

FGFR4

KRAS

MYC

PIK3CA

Chromosomal aberrations (Gene fusions)

7 genes

ERBB2

FGFR1

FGFR2

FGFR3

NTRK1

NTRK2

NTRK3

Indications for genetic testing:

Breast cancer patiens to:

Choose of cancer therapy
Monitor and adjust therapy in case of disease relapse

TARGETED THERAPIES FOR RECURRENT UNRESECTABLE OR STAGE IV (M1) breast cancer

(NCCN Guidelines Version 3.2022)

Breast Cancer Subtype

Any

Biomarker

HER2

FDA-Approved Agents

Trastuzumab
Pertuzumab
Margetuximab
Ado-trastuzumab emtansine
Fam-trastuzumab deruxtecan

Any

BRCA1/BRCA2 mutation

Olaparib
Talazoparib

HR-positive/HER2-negative

PIK3CA activating mutation

Alpelisib + fulvestrant

TNBC

PD-L1 expression

Pembrolizumab + chemotherapy (albumin-bound paclitaxel, paclitaxel, or gemcitabine and carboplatin)

Any

NTRK fusion

Larotrectinibe
Entrectinibe

Any

MSI-H/dMMR

Pembrolizumab
Dostarlimab-gxly

Any

TMB-H (≥10 mut/Mb)

Pembrolizumab

Consulting with a clinical geneticist and/or an oncologist to interpret test results and select cancer therapy is required.

Consulting with a clinical geneticist and/or oncologist is required to interpret test results and make a decision about cancer therapy.

Hotspots (SNV/indels)

Copy number variations (CNV)

Chromosomal aberrations (gene fusions)

Technique sensitivity and specificity
Fast execution time
Concurrent identification of all types of mutations, including structural rearrangements
Minimum requirements for the quantity and quality of samples
Reducing time of analysis