Hereditary colon cancer gene

shelloz1

I had BC almost 5 years ago, and recently been told that I have the Hereditary Colon cancer gene.

I haven't read much on the boards about this, and I'm wondering, does this put me at an even higher risk?  Is there any recommended screening (other than colonscopy)?  Is there anything ths is required as a precuation?

thanks

Shelley

Mutd

Shelley, there are more than half dozen different genes in hereditary colon cancer, most of them don't do much to breast cancer risk, but some ( not all ! ) increase ovarian or maybe uterine cancer risk. The most common Ashkenazi Jewish mutation linked to colon cancer is sort of weak, probably not even doubling the odds of colon cancer ... but it is very common and therefore the geneticists could compare hundreds of mutation carriers with hundreds of negatives. With so many people in a study, even minor risk differences become clear.

 So it all depends on which colon cancer mutation has been found.

shelloz1

I don't know if this makes sense, but it is written:

APC and also 11307K

Shelley

Mutd

Yes, I should have named, I was almost certain that it would be this genetic variant, the most common in Askenazim and also not even nearly as dangerous as the BRCA mutations. Only its correct spelling is "I1307K" (first letter "i").

If you ever wanted to skip a colonoscopy, then this genetic result is a good hint that you probably shouldn't. But it doesn't look like there is any breast cancer connection. This Israeli group looked far and wide and didn't find any link.

shelloz1

Hi Mutd,

Thanks for letting me know.

I have a lot of cancer in our family, mostly related to colon, pancreas, stomach, etc. How much higher risk does this gene put me at for those?  

Shelley

Mutd

Shelley, are you confident that there isn't another genetic reason for these cancers? It is really a question for a good Genetic Counselor, because much depends on how the cancer cases connect to one another on a family tree, how early they happened, where there also cancer-free relatives, and so on...

In my own family most of the links were severed by the Shoah, and then there were several cancers of different sorts, some in my mother's family, some in my father's family ... and in the end people just gave up looking for answers, after going through all the "easy answers" like BRCA and discovering that it just doesn't explain the situation. But your family may be larger, and maybe a GC will fnd some clues. I'm sure however that I1307K isn't the most important piece of your puzzle ... important of course, but just not strong enough to explain it all?

shelloz1

Hi Mutd,

I have an appointment with a GC at Sunnybrook on August 8th. They have all the family history, and I'm sure they will look it over and see what connection can be made. On the high risk board, someone wrote that the APC gene is connected to FAP which seems to be uncommon, is this correct, I'm confused.

Shelley

Mutd

Yes and no, Shelley. APC gene in general is connected to Familial Adenomatous Polyposis, but only some mutations are linked to this severe hereditary cancer condition (and it is extremely rare among the Ashkenazim anyway). Others are called "attenuated" FAP (AFAP) which is a much milder condition. And then there is I1307K which is in a class of itself, so mild an increase in cancer risk that it is virtually invisible in families (but it could be seen, statistically, in a comparison of hundreds of people)