Genetically based breast cancer: Risk assessment, counseling, and testing

Great progress has been made in our understanding of the factors associated with breast cancer, the most common cancer in women both in the United States and in the world. There is ample evidence that several epidemiologic risk factors, including age, ethnicity, mammographic density, reproductive factors, a history of benign breast disease, exposures to radiation, alcohol consumption, and exogenous hormones, are related to the risk of developing breast cancer. Recently, the genetic basis of breast cancer has been explored, and specific germline mutations have been identified as likely responsible for 5–10% of all breast cancers. Mutations in the BRCA1 and BRCA2 gene account for the largest share of hereditary breast cancer. Other hereditary syndromes associated with an increased risk for breast cancer include Li-Fraumeni syndrome (TP53), Cowden syndrome (PTEN), Peutz-Jeghers syndrome (STK11), and diffuse gastric cancer syndrome (CDH1). Genetic counseling and testing for these syndromes are clinically available. The counseling process provides information on the genetic, biological, and environmental factors associated with an individual's risk for cancer, facilitates the testing and interpretation of genetic test results, provides appropriate options and recommendations for prevention and screening, and offers psychological support to individuals and families in coping with their genetic risk. Risk management strategies include aggressive screening protocols, chemoprevention, surgical prophylaxis, and lifestyle changes.