October is Breast Cancer awareness month

Breast Cancer is the most commonly diagnosed cancer in women. National Breast Cancer Foundation, Inc 1 reports that it is the second leading cause of cancer death among women.

About 1 in 8 women in the general population will develop breast cancer during their lives1, but for carriers of BRCA1/2 mutations, that risk may be as high as 70%.  In general, the chances of having a BRCA1/2 mutation are low, but genetic counselors have long been using personal and family histories, along with published screening guidelines to determine who should consider genetic testing for BRCA1/2 mutations. These guidelines, however, are constantly evolving as more is learned about hereditary cancers, and new evidence suggests that they may not be sufficient to identify BRCA1/2 mutation carriers.

New studies around BRCA1/2 screenings  

Current guidelines are based on several factors, such as personal and family histories of cancers – particularly rare tumor types, cancers at a young age, and multiple primary cancers – as well ethnicity, since some mutations are more common in certain ethnic groups, like those of Ashkenazi Jewish ancestry2.

New studies have shown that these guidelines may fail to identify women carrying BRCA1/2 mutations. Geisinger recently sequenced 50,726 individual’s exomes, and identified 89 carriers of BRCA1/2 mutations3.  Of these 89 carriers, 44 did not meet published guidelines for clinical BRCA1/2 testing. Similarly, Counsyl offered a three-month free hereditary cancer screening program to women, and about half of the 108 women who tested positive did not meet NCCN testing guidelines4. The Women’s College Hospital in Toronto also found that only half of the individuals they identified with mutations met guidelines for testing5. These findings represent only the most recent evidence in a controversial push by some experts for population based screening for hereditary cancer mutations.

 

Other challenges with BRCA1/2 testing

Another major challenge to genetic counselors, and frustration for patients, is the identification of a variant of uncertain significance. This is a change to the gene that may or may not have damaging effects, which means even after genetic testing, the risk for developing cancer cannot be determined. It is estimated that up to 10% of individuals tested for BRCA1/2 will have a variant of unknown significance 6. EGL helps to minimize the number of VOUS’s through its commitment to “freeing the data.” Every variant identified and classified by EGL is submitted to public databases so that other clinical laboratories and genetics professionals can use the information to potentially help their patients. Collaboration is a strong force for variant classification.

These are the tests available at EGL Genetics for Breast and Ovarian Cancer testing. Please comment or reach out to us for additional information.

Sources

  1. National Breast Cancer Foundation Inc.
  2. S. Preventive Services Task Force, Risk Assessment, Genetic Counseling, and Genetic Testing for BRCA-Related Cancer in Women: Clinical Summary of USPSTF Recommendation. AHRQ Publication No. 12-05164-EF-3. December 2013.  
  3. Manickam K, Buchanan AH, Schwartz MLB, et al. Exome Sequencing–Based Screening for BRCA1/2 Expected Pathogenic Variants Among Adult Biobank Participants. JAMA Network Open. 2018;1(5):e182140. doi:10.1001/jamanetworkopen.2018.2140
  4. Heger,M (2016, Mar 22). Counsyl Finds Many Women Who Meet Cancer Screening Guidelines Not Getting Tested
  5. Canadian BRCA Screening Project Aims to Demonstrate Public Health Benefits of Universal Testing Program.
  6. Peshkin BN, DeMarco TA, Brogan BM, Lerman C, Isaacs C. BRCA1/2 testing: Complex themes in result interpretation. Journal of Clinical Oncology 2001; 19(9):2555–2565.