a hundred different types of cancer. But many people don't really know what is cancer? And

the answer to that question is very simple. If we look at a normal cell, on the inside

of the cell is the nuclei. And that contains DNA. And the DNA contains genes that control

the actions of the cell. And one of those important actions is how a cell makes a copy

of itself. How it goes through what we call the cell cycle. And so if you take a normal

cell and put it in culture it will simply make a copy of itself. And if there's room

those cells will make copies of themselves and they'll keep doing that until they fill

up that area. And if one of these cells dies then an adjacent cell is going to jump into

that cell cycle and it's going to fill that hole. And so that's how you went from a zygote

to the trillions of cells that are inside your body. And that's also how you replace

cells. And so your skin is constantly losing cells off the surface. But we're creating

cells underneath that. And so the cause of all cancers is the same. There is going to

be damage to the DNA. And so that DNA is made up of what are called nucleotides. And there

are tons of genes in there that are controlling this cell cycle. When a cell should make a

copy of itself and when it should stop dividing. And so a mutation is simply damage to that

DNA. Now it could just occur spontaneously. If we all live long enough we're all going

to develop cancer because these mutations are going to start to accrue during our life

time. But we can also increase the rate of those mutations using the environment. And

so for example if we smoke cigarettes that could cause mutations to the DNA. Increases

in UV radiation. We're finding decreases in exercise. Increases in certain types of diet

can cause mutations. And that can cause problems in the cell cycle. And so let's say we get

a mutation in this cell right here. There are going to be genes within that cell that

sense something is wrong. And lots of times it will undergo apoptosis where that cell

dies and another cell moves inside. But during our lifetime we start to accrue more and more

mutations. And eventually enough mutations build in one of those cells and it becomes

not a normal cell but a cancerous cell. And this takes a long time for that to occur.

And so this is a pretty awful graph. This is the increase in the popularity of cigarettes.

And so this is the number of cigarette smoking per person per year. And so as they were doing

that they were increasing the mutations inside their body. And we can look decades later,

we see the causation. We can see an increase in lung cancer in men as well. And so as we

make those mistakes in our cell we form these cancerous cells. Now what does a cancerous

cell do? It doesn't matter that there are cells around it. It is simply going to divide

and divide and divide. Over and over and over again. And eventually what you create is a

tumor. Now there are two types of tumor. If those cells are restricted to that one area

and stay within a membrane we call those benign tumors. And that's not cancer. But if there

is no restriction to that area it becomes what's called a malignant tumor. And that's

really a definition of what cancer is. It's when we have these uncontrolled cell growth

and those cells show uncontrolled cell growth spread throughout our body. And so this is

a video of some cancerous cells. And so instead of just growing and doing the jobs of the

cell, you can see they are kind of misshapen. And all they do is make copies of themselves

and copies of themselves over and over and over again. That's where all of the energy

is going. Now if that was restricted to one area it wouldn't be as big a deal. But they

can move to different areas of the body. And so if we have a tumor right here, it can start

to invade the tissues around it. And so that tumor can not only get larger, but it can

move into new areas. And if that tumor gets into the lymphatic system or the circulatory

system, it can move around our body and it can settle somewhere else. And so that's the

problem with a malignant tumor. And so we name cancers based on the tissues and the

organs that they infect. So this would be lung cancer. But we could also have colon

cancer. Or maybe pancreatic cancer or breast cancer. It's basically named on the tissue

of where it is. Now each of those cancers, even though the cause is the same, damage

to the DNA which produces uncontrolled cell growth, the way they manifest the disease

is going to be totally different. And so if you look at this x-ray we can see that this

is somebody who has lung cancer. And there's going to be a tumor right there. And what

we're finding is not only are all these different types cancer different, but each of those

individual tumors are different. And between two people those tumors are going to be different.

And even within the cells of the tumor they're going to be different. And so what does that

mean? Well even though we might treat one tumor, we're going to find that within that

tumor there are going to be different cells. Each of those have different genetic problems.

And so we could treat most of the tumor, remove most of it, but it is going to come back eventually

over time. And so what do we have for treatments? And so since cancer is uncontrolled cell growth

we want to find those cells and quickly as we can. And so screening is the most important

thing. Once we find that cancer has developed and we find that tumor, the first thing that

we want to do is we want to remove that. And so surgery is generally what happens next.

We remove that tumor. We also use radiation. In other words we're not going to be able

to remove all of those cell. There are going to be extraneous cells around it. And so we

can target this with ionizing radiation. And we can kill all those cells. Now this has

dangers as well. And so we try to restrict that to that one area. But it can cause damage

to the cells around it. And then often times we'll use chemotherapy. Now what is chemotherapy

doing? It's going throughout your whole body. And it is targeting cells that are actively

dividing. Cells that are going through this cell cycle. And so that's why it affects,

for example, you get a lot of nausea. Because it's affecting those cells in your digestive

tract. Or you lose your hair because it is affecting those cells that are quickly making,

that are constantly making new hair. And so with all of these we're getting better and

better at treating cancer. What's the future hold? Well we're really just treating just

all cancers with these three methods the same. And so what we'll see is if we can get into

the genetics and we start to understand how each of those cancers are different then we

can start to target them. And so one of the breakthroughs was Gleevec which is one of

these first drugs that's targeting a specific type of leukemia. And it was affecting a specific

machinery within that cell. And so again, the more we understand about cancer we find

that they are all the same but the causes are going to be different. And so what is

cancer? It's simply uncontrolled cell growth. And I hope that was helpful.