Understanding hereditary cancers
Kathryn E. Vinson, MS, CCRC
We’ve all heard the saying “it runs in the family.” This, of course, can encompass any number of traits – height, eye color, sense of humor, or sadly – disease conditions. Some of us seem to take after one person more than another. For me, its my paternal grandmother. I got it all from her – thyroid issues and bad feet. So, given the fact that she has also survived breast cancer (twice!), I was just a tad concerned about the possibility of inheriting that from her as well. Fortunately, her cancers were found to be BRCA negative, but that little seed of worry still nags from time to time.
We hear a lot about hereditary cancers in the media, but what exactly does that mean? And what kinds of cancer are known to be hereditary or genetic? Let’s take some time today to discuss these very important topics, as well as some clues that hereditary cancer may run in your family.
How genetics can influence cancer
Basic biology tells us that we have two of each gene – one from mom and one from dad. Among the genes that control our physical appearance and body functions, there are some amazing little guys known as tumor suppressor genes. It is their job to keep our cells under control. What do I mean by that? Well, without these tumor suppressors, cells can divide too rapidly, or in an incorrect manner. It is their job to keep these in check. So, when tumor suppressors are damaged – either by inheritance or by acquired damage (think environmental), we can wind up with cancer.
Let’s look at it another way. Say you take one of the commercially available genetic tests and it shows that you are positive for a mutation in one of the tumor suppressor genes. Does this mean that you will get cancer? No – it does not. What it means is that if your cells decide to go haywire and start dividing out of control, your tumor suppressor genes may not function correctly, and your body will have a harder time controlling that growth by its own means.
What types of cancer are hereditary?
There are several types of cancer that we know to have inherited causes. Please note that the cancers listed below are those that are known to have a genetic component. It is possible to have these cancers without having the genetic mutation, as well as there may be genetic factors in cancers that we don’t know about yet.
- Hereditary breast and ovarian cancer syndrome – typically caused by mutations to BRCA 1 and/or BRCA2.
- Lynch syndrome – hereditary non-polyposis colorectal cancer. This can result from damage to one of five different genes.
- Li-Fraumeni syndrome – a very rare inherited disorder that can cause several cancers including sarcomas, brain cancers, breast cancers, and leukemia, that is linked to damage to the TP53 and CHEK2 tumor suppressors.
- Familial melanoma – inherited changes to the CDKN2A and CDK4 tumor suppressor genes can increase the risk of developing melanoma.
- Hereditary diffuse gastric cancer – a change in the CDH1 gene, and perhaps the CTNNA1 gene, can increase a person’s risk of developing a specific type of diffuse gastric cancers.
How can you tell if there is cancer causing gene in your family?
Short of having genetic testing done (which may be ordered if there is indeed cause for concern, the American Cancer Society provides us with the following guidelines for determining if cancer may follow a familial pattern (directly quoted):
- Many cases of the same type of cancer (especially if it is an uncommon or rare type of cancer)
- Cancers occurring at younger ages than usual (like colon cancer in a 20-year-old)
- More than one type of cancer in a single person (like a woman with both breast and ovarian cancer)
- Cancers occurring in both of a pair of organs (like both eyes, both kidneys, or both breasts)
- More than one childhood cancer in siblings (like sarcoma in both a brother and a sister)
- Cancer occurring in the sex not usually affected (like breast cancer in a man)
- Cancer occurring in many generations (like in a grandfather, father, and son)
If you have seen patterns such as this it is definitely worth discussing with your physician or a genetic counselor.
Another interesting theory that I read discussed genetic predispositions to certain habits such as smoking and alcohol consumption leading to cancers of the lungs and the GI tract. While the genetic trait doesn’t directly cause the cancer, it leads to a propensity to engage in behaviors that are known to cause cancer.
As always, much love, many prayers, and abundant blessings to all of the warriors out there!