Abstract
Molecular testing of genetic and genomic variations is already an integral part ofbreast cancer treatment. Patients with a family history of breast cancer or other malignant tumours, bilateral, triple negative breast cancer or breast cancer at an early age are indicated for genetic testing in order to detect possible genetic condition underlying their disease.
Availability of PARP inhibitors that are selectively effective in patients with BRCA1/2 mutation is a rational reason to test a possible genetic background even in many patients diagnosed with advanced breast cancer. Tumour genome profiling is the standard of care for many types of malignancies and is becoming increasingly important in the treatment of advanced breast cancer.
Target mutations, such as PIK3CA, HER2 and rare cases of mismatch deficiency, or other targets for tyrosine kinase inhibitors are the basis for choice of targeted therapy. Development of methods for cell-free DNA sequencing should allow for wider and easier tumour genomic testing.
Transcriptional expression signatures have become the standard of care for the treatment of hormone-dependent breast cancer in the early stages of the disease. These tests provide prognostic information to determine adjuvant hormone therapy and the potential benefits of adjuvant chemotherapy.
Molecular testing is likely to be part of the clinical care of most breast cancer patients in near future.