1. SECTIONS:
2. preface & acknowledgements
3. genetics at a glance
4. contacts, support & testing
5. testing & pregnancy
6. newborn screening
7. cancer in the family
8. cardiovascular conditions
9. chromosomal conditions
10. clotting & bleeding conditions
11. cystic fibrosis
12. diabetes
13. fragile X syndrome and other causes of developmental delay
14. haemoglobinopathies
15. hereditary haemochromatosis
16. neurofibromatosis
17. neurological conditions
18. psychiatric conditions
19. genetics in practice
20. emerging genetic technologies
21. glossary

Familial breast and ovarian cancer

 

1. Breast cancer
2. Affects about 1 in 11 women before the age of 75 years
3. The most common cause of cancer deaths in women
4. Also occurs in men, but it is rare
5. Epithelial ovarian cancer
6. Affects about 1 in 100 women before the age of 75 years
7. The leading cause of death from gynaecological cancer
8. There are many risk factors that can influence a woman’s chance of developing breast or ovarian cancer.
9. The main risk factors are:
10. Being a woman
11. Increasing age: most women who develop breast or ovarian cancer are over the age of 50
12. Family history of breast and/or ovarian cancer
13. Family history does not necessarily imply an inherited genetic cause. However, at least 1 to 5% of breast cancers, and 5 to 10% of ovarian cancers, involve the inheritance of a mutated gene.

 

Genetics

1. Mutations in the BRCA1 and BRCA2 genes are associated with both breast and ovarian cancer (see Table 2).
2. Environment also plays a role in causing breast and ovarian cancer, but the specific environmental factors are still unknown. They may include exposure to various hormones, and radiation, lifestyle and diet.
3. Mutations in some other genes have also been associated with an increased risk of developing breast or ovarian cancer, as well as some other cancers (see Table 2).
4. The vast majority of affected women do not carry an inherited mutation in a known breast or ovarian cancer predisposing gene.
5. Inheriting a gene mutation in the BRCA1 or BRCA2 gene means an individual inherits a predisposition or susceptibility to breast and ovarian cancer.
6. In women who develop breast cancer before the age of 40 years or bilateral breast cancer, the prevalence of BRCA1 and BRCA2 gene mutations is higher.
7. Inheriting a mutation in a BRCA1 or BRCA2 gene also slightly increases the chance that a person will develop other cancers.
8. Inherited mutations in the BRCA1 and BRCA2 genes:
9. Follow an autosomal dominant pattern of inheritance, meaning that if a person has a mutated copy of one of these genes, each of their children has a 50% chance of inheriting the mutation.
10. Can be inherited from either the mother or the father.
11. Are thought to be involved in 1 to 5% of all breast cancers and up to 10% of all ovarian cancers.
12. Mutation searching for a familial breast and ovarian cancer gene mutation is an expensive and often lengthy process that can potentially produce 'uninformative' results (see Contacts, support and testing).
13. Sometimes a causative mutation cannot be found in a person with breast or ovarian cancer. In this case, it cannot be presumed that a mutation is not present. Therefore 1° relatives should be considered to be at 50% (or 1 in 2) risk of having inherited a mutation and participate in a screening and prevention program according to national guidelines (see ‘Category 3’ for breast cancer and
    ‘Category 2 (potentially high risk)’ for ovarian cancer, detailed below).
14. Asymptomatic family members, shown on predictive testing not to have inherited the mutation conferring a predisposition to breast and ovarian cancer, still have an average risk of developing these cancers based on their age. These individuals should follow recommendations for population screening. However, they can be spared the intensive screening needed by someone who has/may have a mutation.

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