Hereditary Cancer

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In contrast to sporadic cancer, heritable forms of cancer do run in families. Only 5% to 10% of cancers are thought to be heritable (American Cancer Society, 2009). Heritable cancers are caused by germline mutations that alter genetic information in sperm or egg cells (gametes) involved in fertilization, thus passing a mutation on from one generation to the next.

Clinical Example: Theresa is a 21-year-old Ashkenazi Jewish woman. She is single and does not have children. Although she is currently cancer-free, Theresa worries about developing cancer. There is a significant family history of breast and ovarian cancer in Theresa's family. Because of the family history, Theresa's mother underwent genetic testing for a hereditary breast and ovarian cancer syndrome last year. Her mother's genetic test was positive for a mutation in the BRCA1 gene, a tumor suppressor. Women who have the mutation found in Theresa's mother are at increased risk for breast and ovarian cancer.

BRCA1 is inherited in an autosomal dominant fashion, meaning that Theresa was born with a 50% chance to have the same BRCA1 mutation her mother has. The presence of the BRCA1 mutation does not guarantee that cancer will develop. For example, a woman born with a mutation in the BRCA1 gene has a 55% to 65% chance to develop breast cancer (Chen & Parmigiani 2007). She also has a 13% to 44% chance of not developing breast cancer. To learn more about her risks for cancer and preventive healthcare options, Theresa plans to visit a local cancer genetic counselor.

Elaine: Ovarian cancer dx age 46y, unilateral.

Claudia: Breast cancer dx age 46y, unilateral.

May: Breast cancer dx age 49y, unilateral. Breast cancer dx age 51y, contralateral breast, primary tumor.

View ReferencesHide References
Campeau PM, Foulkes WD, Tischowitz MD. Hereditary breast cancer: new genetic developments, new therapeutic avenues. Human Genet. 2008; 124: 31-42. Available at: Accessed on: 2014-09-02.
Cancer facts and figures 2009. American Cancer Society. 2009. Available at: Accessed on: 2009-10-12.
Chen S, Parmigiani G. Meta-analysis of BRCA1 and BRCA2 penetrance. J Clin Oncol. 2007; 25: 1329-33. Available at: Accessed on: 2014-09-02.