So I’m at risk for cancer. What does that mean, exactly?

WARNING—LOTS OF NUMBERS AHEAD!

My BRCA1 mutation puts me at “high risk” for cancer.  But what does that mean, exactly?  Which cancers do I need to be concerned about? How high is my risk?  Is it really that significant? How concerned do I need to be?

Each BRCA mutation has its own risk profile.  A person with a different BRCA mutation and family history may have a different risk profile than me.  Therefore, I have chosen to rely on my individual genetic testing results to determine my specific risk.  (I will discuss the genetic testing process in another blog post.)

In big, bold, capital letters, my report screamed POSITIVE:  PATHOGENIC MUTATION DETECTED.  There was no missing it.  To get the details, I needed to scroll down to the Interpretation section.  In part, here’s what it says:

Risk estimate: 36-83% lifetime risk of breast cancer and 8-50% lifetime risk of ovarian cancer, and increased lifetime pancreatic cancer risk. 

Those are big ranges.  So, I then scrolled down to the Additional Information section to get some more details.  This section cited several journal articles and research studies, mentioned things like amino acids, tumor suppressor genes, and more, so wading through it was a bit more complicated.  But here are key findings.

In the first paragraph:  Cumulative female breast cancer and ovarian cancer risks (by age 70) associated with this specific mutation have been estimated in the literature at 67% (range: 36-83%) and 33% (range: 8-50%), respectively.

In the second paragraph: Early studies estimated a female breast cancer risk of 87% by age 70 for female BRCA1 mutation carriers; however, more recent studies suggest a risk of 57-65% by age 70. The risk for ovarian cancer, including primary peritoneal and fallopian tube cancer, by age 70 in women with BRCA1 mutations is estimated to be 39-40%.

More big numbers.  And then there was this at the end:

In addition, both men and women have an increased risk for melanoma and pancreatic cancer compared to the general population, although the exact risks have not yet been well defined.

Great.  So not just ovarian and breast cancer, but also melanoma and pancreatic cancer.

And, finally, on the next page, I found this:

It is estimated that that 1 in 8 women will be diagnosed with breast cancer over the course of a lifetime. Inherited mutations in two highly penetrant genes, BRCA1 and BRCA2, appear to be responsible for about 5% of total breast cancers, and result in lifetime breast cancer risks of up to 87% for women and up to 10% for men. Mutations in these two genes also significantly increase lifetime risks of ovarian (up to 40%), pancreatic, and prostate cancers depending on the gene and gender of the individual.

So if I’m reading this right, overall risk for breast cancer in the general population is about 12.5%, but my risk (with my specific mutation) is about 67%, but may be as high as 87%.  And my risk of ovarian cancer, which in the general population is about 1.2%, is at least 33%. 

Wow.  I’ve just learned that I may be a ticking time bomb.