The Big "C"

Posted by Aaron

Sunday, August 23, 2009

WOW - I just realized how long it's been since I posted. Sorry, folks. I could give reasons, but they'll just sound like excuses. Let's get back to work!

Cancer. This is a loaded topic and one for which there are entire textbooks. I'll discuss cancer treatment in the next posting. For now - we'll talk about what it is, why it happens.

First some definitions:

Tumor - a coherent overgrowth of abnormal cells. This can also be used as a pleural noun.

Mass - I use tumor and mass interchangeably. For me - mass is more accurate. I feel a 'mass.' There is a 'mass' on the shoulder. Mass does not describe the behavior of the cells.

Neoplasia - Anytime a group of cells starts growing in a way that is not 'normal' like the parent cells, it is neoplasia. So neoplastic cells aren't just overgrowths of normal cells, these are cells that have chosen to ignore convention and strike out on their own. Neoplasia can be benign or malignant. It simply means that it is a 'new growth' of cells.

Benign - This is an adjective (or adverb) that describes the behavior of the tumor. A mass that behaves, will not spread to other parts of the body is benign. Benign masses in bad places may do bad things (a benign tumor in the brain is still not a good thing to have - there's only so much room up there to deal with and the brain needs all the room it can have).

Malignant - The opposite of benign. This describes a tumor or behavior that is not going to behave. Malignant tumors are usually associated with something that will spread to other parts of the body or will invade locally. Malignant = bad.

Cancer - a term that is used interchangeably with malignant. Some folks use cancer to mean all tumors. Usually if you say cancer - you mean something that is bad.


How do tumors start?
Believe it or not - you have cancer. Seriously. Every day your body has a few cells in it that don't replicate like they are supposed to. They forget who they are. The don't listen to the body when the body says STOP. There is simply something WRONG with them. 99-100% of the time, the body recognizes these guys and sends in the killer-T cells. These white blood cells see the bad cells and then kills 'em. Kills 'em dead.

And then there is the exceptionally rare cell that survives. The body doesn't recognize that it is bad. It's allowed to continue growing because the body thinks it's supposed to. Next thing you know - there are a few billion cells and you have a mass, or tumor.

So what does it mean when I hear that some chemical or product causes cancer?
ANYTHING that damages cells or screws with their DNA could cause them to start behaving badly. If it brings about a change in the cell that would ultimately cause a tumor is referred to as oncogenic. Lots of research goes into this field.

There are oncogenic chemicals (saccharine, tar), radiation (sunlight, x-ray, gamma ray), and even oncogenic viruses (feline leukemia). Some of these causes trigger damage to DNA (radiation) that will cause random mutation and tumor genesis. Others cause certain genes in the cell to turn off or on and as a result the cell stops listening to instructions.

Some cancers have a genetic predisposition. Some individuals may be more likely to develop cancer because they either have a gene or lack a gene that regulates the cancer formation. We don't understand all of these genes yet, but it's a HUGE area of research.

You can try and prevent exposure to environmental triggers of neoplasia. You wear sunscreen, you don't use a tanning bed, you filter your water, are careful with household chemicals, eat healthy, and don't smoke. You can't control your genes. You were born with them. So you try not to piss them off and instead try to help the body recognize when they've gone wrong to catch a tumor before it kills you.

In humans, there are certain familial cancers. In dogs and cats, there are breeds that have been associated with particular tumors. Boxer dogs and golden retrievers are seriously over represented when it comes to cancer. So clearly these guys have something that either pre-disposes them to making a cancer OR something that keeps their body from catching the cancer once it's formed and killing it before it becomes self-sufficient.

What happens after the tumor is started?
By the time the tumor is operating on it's own, it is no longer listening. It's past the point where the body can stop it. It's like a petulant, super-independant child. The body can try to convince it to slow down, but it doesn't want to. It still gets all of it's energy from the parent, still relies on the body for a home, but doesn't care what's best for it's host. It's parasitic.

So now we have to think in terms of benign versus malignant. Benign means it usually won't invade and it will not spread to distant parts of the body. Lipomas, or fatty tumors, are good examples of this. Nearly anyone with a dog has seen a fatty mass. These usually feel soft, slightly squishy, and are just under the skin. These guys are benign. They aren't going to spread. However, they may not behave. If you get one in the armpit that decides to grow to the size of a melon you may not have function in that leg. Benign tumor - bad result.

Malignant masses are going to be locally invasive, aggressive, and may spread to distant places. These are the bad guys. The cancers. Malignancy typically means that we must intervene and treat or they will kill you. Next post I'll talk about different treatment options. Generally speaking, we're talking surgery, radiation, or chemotherapy.

These are just general principles. I can discuss individual tumor types in future posting. If you have a particular cancer/tumor that you want me to discuss, please e-mail or post so I can write on that topic. There are some really interesting tumor types out there that do all kinds of weird and horrible things to the body. There are simply too many to try and lump together.

I promise not to allow so much time to elapse between postings. Talk soon.