Download Breast Cancer web page

Breast Cancer
• Ten percent of breast cancer is hereditary.
• Or 23,000 women a year with a genetic basis for their cancer.
• The most common mutations in this group are BRCA1 and BRCA2 comprising roughly 7% of all breast cancer.
• These two proteins are part of a DNA process called “homologous
repair”.
• If the DNA repair process malfunctions then
DNA errors accumulate. This leads to cancer
formation.
• In BRCA1 the cancers are predominantly breast
and ovarian.
• In BRCA2 the cancers are female and male
breast, ovarian, prostate, and in some families
pancreatic.
• The risk of cancer differs between BRCA 1 and 2.
• A meta-analysis of ten studies conducted both in high-risk
clinics and population-based settings reported that the
cumulative risk of breast cancer by age 70 years was 57% for
BRCA1 and 49% for BRCA2.
• Ovarian cancer risk was 40% for BRCA1 and 15% for BRCA2.
• Male breast risk is 10% for BRCA2 and 1% for BRCA1.
• Prostate cancer - 5 to 7 fold increased risk for BRCA2 and 1.8
fold increased risk for BRCA1.
In general we use the following guidelines to identify
carriers
• Today BRCA testing should include the search for
both mutations and large rearrangements.
• Mutations are misspellings of the DNA sequence
and large rearrangements are errors that occur
when DNA replicates and some of the sequence is
left out.
• The testing for large rearrangements is also known
as BART –BRACAnalysis® Large Rearrangement
Test
As you can see BRCA1 and 2 make up most of the genes associated
with breast but several others make up the remaining 3%
• Some gene mutations are associated with well defined
clinical pictures such as Li-Fraumeni and Peutz-Jeghers
Syndrome.
• Others are still being explored, such as CHEK2 and
PALB2.
• If you are negative for BRCA1 or 2, you may have one of
these other gene mutations.
• To pursue this there are “Reflex Panels” that contain all
these genes in one test and you may be a candidate for
this type of testing.
• Breast cancer is our most common problem and a good family
history is key in determining if you have a genetic reason for
breast cancer in your family.
• Details about your family history that you might not think are
important may make the difference between whether or not
you qualify for testing.
• We use several models to calculate your risk – such as Upenn,
Tyrer-Cuzick, Gail, Myriad.
• If you have a genetic mutation we will give you information
that will help you make decisions for you, your children and
your extended family.