Cancer Treatment - How to kill the tumor and not the patient

The title sounds a bit hard-core, but it's the truth.

Our last discussion was about how and why we get tumors. Some of these tumors become what we would refer to as cancer. Once a particular tumor has been identified and we know what we are dealing with, we can then begin discussing treatment.

The words radiation or chemotherapy often begin to evoke visceral reactions from owners. Most people have been exposed to the idea of chemotherapy or radiation because of a family member or friend who has battled cancer. Some chemotherapy and radiation options are pretty rough on the body. Some patients get very sick. But not everything that counts as chemo or radiation is hard on the body at all It really depends on the specific protocol.

In my opinion, it's all about QUALITY of life. Some would see it differently and say that QUANTITY is the more important half of the equation. I disagree. Quantity is nothing without quality. The sticking point becomes defining the point at which quality and quantity intersect at an acceptable point for YOU and YOUR PET.

By example, I am currently treating my own dog for stage 4-b lymphoma. That's about as bad as it gets. We decided to start chemotherapy because many of the initial drugs I was going to use in her treatment were fairly benign and it was worth a shot. Surprisingly, she's responded very well to her chemo and hasn't had any bad days because of it.

Until now.

I made the decision to go ahead and give her the doxorubicin. That is the one most likely to make her 'feel bad' for a few days. My decision to use that drug was based on the fact that a few days of nasty were worth the few weeks or months of happy. That was my take on it. Others would argue that the cost and misery of a few days is not an acceptable price to pay for a few weeks or months.

The take-home point is that the decision to treat and the decision how to treat is not something that can be made for you. Your doctor should give you options and you should consider the total picture and make an informed decision. For some, the answer is an easy. Hopefully you enjoy the support of a caring oncologist or primary care veterinarian and you will be an active part in the decision making process.

Staging the tumor:
Staging is something done when we are dealing with a malignancy (cancer). The goal of staging is to evaluate how 'badly' the tumor is behaving so that we can determine what therapy is required. It is necessary to help direct types of therapy in most cancers.

How we stage a tumor depends on tumor type. Some tumors tend to metastasize to the lungs first. Others met to a regional lymph node first. In the case of lymphoma we have to determine if the tumor is in the spleen, liver, or thymus and if it is in lymph nodes. Different locations have different prognoses because. Believe it or not - the same tumor found in two different places could behave dramatically differently.

Surgery:
If we are able to physically remove the tumor then we often take this as our first course of action. After all, why would we poison the entire body if we can cure the cancer by physically removing it from the body. There are many tumors where this is the ONLY treatment recommended.

Other times, our goal is to de-bulk the tumor. We know we won't get the entire tumor. We know there will be microscopic tumor left behind. But if we get all of the visible tumor, it makes the microscopic much easier to heal.

Because there is often microscopic invasion of the tumor in surrounding tissues, the amount of tissue to remove is sometimes impressively large. As an example, mast cell tumors require margins of approximately 3cm in every direction. By the time you account for the shape required to close the defect, a patient with a 1/2" mass may end up with a 6 inch incision.

Just like with real estate, it can all be about location, location, location. That same mast cell tumor on the foot simply can't be removed. There's not enough foot left to close the wound. So there are times that tumor location may dictate amputation of a particular body part (toe, ear, etc). Amputation doesn't have to be a bad word. Life without a toe isn't a bad idea if the only other option is death.

Radiation:
Radiation therapy means that energy in the form of radiation (gamma rays, x-rays) is poured into the tumor in hopes of causing such severe damage to the tumor cells that they die off. Unfortunately, normal tissues always get caught in the crossfire. There are some great new technologies that allow for the very precise delivery of radiation to a very tiny area and help minimize the amount of collateral radiation damage. Local reactions like burns (mild or severe) are the usual side-effects. When talking about the skin, that's not so bad. But if you are trying to irradiate a tumor in the pelvic canal, you end up burning the colon a bit, and the colon does not handle this very well. Again - Location, location, location.

Some tumors are particularly sensitive to radiation and die off quickly and easily. Some are very resistant and radiation doesn't really work. Radiation is usually applied to a very specific and focused location, but there are times where it is appropriate to irradiate an entire limb or an entire body. Whole-body radiation is something usually reserved for killing off the bone marrow in leukemia patients prior to marrow transplantation.

Chemotherapy - The 'other' Big C:
The goal of chemotherapy is to poison the body JUST ENOUGH that the tumor cells die but the patient does not. Chemotherapy is generally administered to the entire body. This is good if you have tumor around the entire body, but it also means that you are exposing all the normal cells in the body to the drug.

Nearly all chemo drugs target fast growing cells. This makes sense because the tumors are usually growing quickly. However, there are lots of cells in the body that have to grow quickly. Bone marrow, cells lining the intestines, and hair follicles are the major players. Not all drugs cause the same problems. For instance - vincristine is one of the drugs in lymphoma treatment. It is VERY well tolerated and is pretty uncommon to cause any issues. Doxorubicin, on the other hand, is quite likely to cause pretty severe gastrointestinal problems. In some dogs, it will cause balding.

The moral of the story is that you should not let the name chemotherapy scare you away all together. Some drugs are fairly simple and may provide excellent responses with nearly NO side effects. Others may be tolerated well in one patient but horribly in another. You simply have to weigh all the variables - patient, prognosis, finances, transportation, side-effects.

This posting does not even begin to cover everything. My hope was to at least cover the big picture. Like I say - I'm happy to entertain questions about specific tumors, drugs, or topics anytime. Just e-mail me!

AMH

The Big "C"

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.

AMH