DNA Day experts answer your questions about cancer and genetics

Above: Image © adventtr, iStockphoto.com

If lets say one of our ancestors had cancer and you want to know if you have a chance to get it, can genetics determine if you are getting cancer or not?

Well we're getting there .... there are some (like breast cancer) that have a well-known set of genes that predispose to it. And in some of those, the risk is clear-cut. There are many others, but most of the time genes will not be a guarantee of cancer, but rather raise the likelihood .... So in those cases you might not be sure. Also genes can be influenced by the environment, and the way they express themselves can be changed, so I would say that 'reading' your parents' and grandparents' genes and being able to define yor risk in detail is not here yet.

- Answer provided by Jay Ingram

Does a cancer cell have its own genetic makeup? Or is part of the patient's genetic makeup?

It is usually a mix of both in fact. Many cancers are caused when cells acquire a new mutation that creates a problem for that cell controling its division and removing itself. Even in the case when cancers are caused by a genetic mutation that is inherited, and thus present in every cell in the body, once the cells become cancerous, they often are unable to go through the usual checks and balances that the rest of our cells do, and they accumulate new mutations.

- Answer provided by Dr. Karen Bedard

How do Genetics play a role in the likelihood of an individual getting cancer?

Quite strongly - the mutation of certain genes can mean a person may be born with a dramatically higher life time risk of cancer. Most famously, women born with mutations in the BRCA1 or BRCA2 genes have a 5-fold (or more) greater chance of breast or ovarian cancer in their lives.

- Answer provided by Dr. Aaron Goodarzi

What kind of cancers are genetic? What triggers these kind of cancers, and can we prevent it?

I am a plant geneticist so take my answer with a word of caution. Your genes can make you predisposed to certain cancers. There are certainly some breast cancers for which "predisposing genes" have been identified. However, having "the gene" does not mean you will develop the disease because cancers are triggered by environmental conditions (exposure to cancer causing agents for example). The triggers include UV rays, smoking, bad eating and health habits, exposure to harmful chemicals, etc.

- Answer provided by Dr. Sylvie Cloutier

What types of cancer is there genetic testing for?

Quite a few, these days. While I don't have a comprehesive list handy (science moves too fast, new tests come out every day), there are plenty for things like BRCA1/2 related breast and ovarian cancer, or some of the Myelogenous Leukaemias and also childhood brain cancers such as Neuroblastoma. New testing methods is an area of intense effort within the scientific community.

- Answer provided by Dr. Aaron Goodarzi

What does the DNA structure look like in cancer?

The actual DNA structure, a double helix of wound nucleic acid chains, is the same. What is different between cancer and normal cells, however, is the DNA sequence and, often, amounts. In cancer, the DNA accumulates increasing numbers of mutations. This is what we call genomic instability, and it is a self worsening process. Cancer cells often display loss of some areas of DNA, as well as gains in others. These mutation, losses or gains, generally drive them towards a worsening cancer state (i.e. more aggressive).

- Answer provided by Dr. Aaron Goodarzi

If a mouse has cancer and a cat eats the mouse, can the cat get cancer as a result?

- Answer provided by Gijs van Rooijen

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