Breast and Ovarian Cancer Screening Tests

BRCA1 (BReast CAncer gene 1) and BRCA2 (BReast CAncer gene 2) are genes that produce proteins to repair damaged DNA. Everyone has two copies of each of these genes—one copy inherited from each parent. BRCA1 and BRCA2 are sometimes called tumour suppressor because when they have certain changes, called harmful or pathogenic mutations cancer can develop. People who inherit harmful mutations in one of these genes have increased risks of several cancers—most notably breast and ovarian cancer. People who inherited a BRCA1 and BRCA2 mutation tend to develop cancer at younger ages. Each child of a parent who carries any mutation in one of these genes has a 50% chance (or 1 in 2 chance) of inheriting the mutation. Cells that don’t have any functioning BRCA1 or BRCA2 proteins can grow out of control and become cancer.

DNA (Deoxyribonucleic acid) contains the genetic instructions in all living things. DNA is made up of two strands that form a double helix. A DNA strand has four different bases arranged in different orders. These bases are T (thymine), A (adenine), C (cytosine), and G (guanine). DNA is “read” by the order of the bases, Ts, Cs, Gs, and As. The specific order, or sequence, of these bases determines the exact information carried in each gene (e.g., instructions for making a specific protein).

Genetic cancer risk 5-10% of all cancer is due to a genetic fault (mutation) which can be inherited. Families with an inherited mutation can benefit from cancer risk screening. Families with an increased risk of cancer often show one of the following clues:
• Several relatives with the same or linked types of cancer
• Relatives diagnosed at particularly young ages (before 50)
• Several affected generations
• Individuals who have been diagnosed with multiple cancers
Cancers which can be linked in some families are Breast, Ovarian, Prostate, Pancreatic, Bowel, Womb and Stomach cancers.

Genetic Counsellor can help explain the risks and benefits of a genetic test, the potential results of a genetic test, what the results mean, how family members may be effected, and direct individuals to relevant patient support groups.

Mutations All cancers begin when one or more genes in a cell mutate. A mutation is a change. It creates an abnormal protein. Or it may prevent a protein’s formation. Mutations happen often and may be beneficial, harmful, or neutral. Typically, the body corrects most mutations. A single mutation will likely not cause cancer. Usually, cancer occurs from multiple mutations over a lifetime. That is why cancer occurs more often in older people.

Oncology is the study of cancer. An Oncologist is a doctor who treats cancer and provides medical care for a person diagnosed with cancer.

Targeted therapy is treatment that targets specific genes, proteins, or other molecules that contribute to cancer growth and survival.

Variant of Uncertain Significance (VUS) is a genetic change whose impact on an individual’s cancer risk is not yet known. Everyone’s genes are slightly different. Some genetic changes (variants/mutations) do not affect the gene’s function and therefore do not increase cancer risk. With genetic testing you might not get a “Normal” or “Positive.” You might get an Inconclusive mutation VUS. Unlike harmful mutations that cause cancer or benign ones that don’t, researchers don’t yet have enough information about VUS to know whether they’re involved in cancer. Almost 20% of genetic tests identify a VUS.

Genetic categories of variants/mutations are ranked from most to least severe.

• Pathogenic (harmful, increased risk of disease)
• Likely pathogenic
• Variant of Uncertain Significance (VUS)
• Likely benign
• Benign (harmless)

The categories follow American College of Medical Genetics and Genomics (ACMG) guidelines and genetic results should be shared with a healthcare professional and discussed with a medical doctor.

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