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Hereditary breast and ovarian cancer is caused by pathogenic (‘disease causing’) variants in genes, commonly  related to two genes called BRCA1 and BRCA2. These genes were discovered in 1994-1995 (the acronym BRCA comes from BReast CAncer one or BReast CAncer two). Normally these genes act as tumour suppressors and help stop abnormal cell growth in the breasts and ovaries.  However errors (known as mutations or pathogenic variants) can occur in these BRCA genes, and if a woman has inherited a mutation in one of these genes she has a increased risk of developing breast and/or ovarian cancer. 

Women who carry a mutation in one of these genes may have a 69-72% risk of developing breast cancer by the age of 80 (population risk 11.9%) and a 17-44% risk of developing ovarian cancer. 

Men who carry a mutation have an increased risk of breast cancer, prostate cancer and pancreatic cancer.

​Approximately 1 in 250 people in our population carries a mutation in BRCA1 or BRCA2, and less than 5% of all breast and ovarian cancers can be explained by a BRCA mutation (source: NZ study by Prof Logan Walker)

A parent with a BRCA1 or BRCA2 mutation has a 1 in 2 chance (50%) of passing it onto each child they have. 

Risk reducing strategies include prophylactic surgery, medication and early detection.