Clinical genetic testing in HBOC syndrome
Hereditary breast and ovarian cancer (HBOC) syndrome, which is primarily caused by BRCA1 and BRCA2 mutations, make up 8 to 10 percent of all breast cancers, says a senior consultant.
The inheritance pattern is autosomal dominant and rarely de novo, said Associate Professor Joanne Ngeow Yuen Yie, head of the Cancer Genetics Service, National Cancer Centre Singapore and senior consultant in Division of Medical Oncology at the same centre.
In those with HBOC syndrome, the risk of developing breast cancer by age 70 is 56 to 87 percent, and the risk of developing ovarian cancer is 27 to 44 percent by the age of 75, she said. Besides elevated risk of breast and ovarian cancer, those with HBOC syndrome is also at a higher risk of developing prostate cancer, melanoma and pancreatic cancer.
Genetic counselling for HBOC syndrome should be provided to those with a personal history of or close family member with, for instance: ovarian, fallopian tube or primary peritoneal cancer; breast cancer diagnosed before the age of 50; and men with breast cancer, explained Ngeow.
Currently, there are more than 400 hereditary cancer syndromes identified and the number will increase, she said. Pre- and post-genetic test counselling are important so there is shared decision-making for gene-directed management.
Panel testing will be the way forward. As it is new, there will be pitfalls and clinicians need to be aware of them, Ngeow concluded.