Cancer: What is it, risks, detection, treatment

Cancer...it is something that is happening all the time in our bodies, yet most of the time our bodies fight it off with ease. Cancer is nothing more than a cell, part of ourselves, that starts growing uncontrollably. That’s all. And yet it can kill.

With Elizabeth Edwards relapsing after recovering from cancer, I thought it a good idea to give a brief lesson on cancer. This is a topic I am very familiar with. A big chunk of my professional career has involved studying subjects that are related to cancer. I have also seen someone die of cancer. I know what happens in cancer on the level of molecules, cells…and to a whole person and that person’s family.

Cancer is what happens when a cell escapes from the normal controls that limit its ability to divide. Cell division is how we develop from a single cell—a fertilized egg—into a human being. Cell division is how our hair grows, and how our intestinal lining and blood cells constantly replenish themselves. It is also how injuries heal. Cell division is a very tightly regulated process. It isn’t easy for a cell to divide. Our cells are constantly exchanging messages about what’s going on in our bodies, and most of those messages prevent cell division.

Cells require survival signals from other cells. Without these, a cell will simply commit suicide. They don’t just die. They actually chew up their own DNA, package up their insides into parcels that immune cells can dispose of, and kill themselves. Every cell in our body has to receive these survival signals or they kill themselves. That is one level of control.

Cells normally don’t divide. They have to actively receive signals that TELL THEM to divide. This is in addition to survival signals. If they get survival signals but no division signals, they just sit there, carrying out their basic function, never dividing. Most of the cells in an adult are like this—functioning but not dividing. Of course in children many more cells are dividing because children are growing. And if we are injured, cell division signals are released that tell surrounding cells to divide and close the wound. And some cells, hair follicles, blood cells and intestinal cells, are constantly dividing to keep up with use. But most of an adult’s cells don’t divide. They are quiescent.

Finally, most cells in our body can only divide a certain number of times before they start to lose that ability. This is called senescence. In essence, a cell that has divided too many times starts to have too many problems and they essentially get too old to divide.

These three levels of control have to fail for a cell to become cancerous. Cells have to think they are continuously getting survival signals and division signals, and gain the ability to escape senescence. Such cells become, essentially, immortal and can grow indefinitely. This is cancer. However, at this point cells are generally still benign. That means they are immortal and always want to grow, but there are still some kinds of control that keep them from becoming too crazy. Such cells are dangerous…but usually not deadly.

Cells that are next to each other exchange signals saying “STOP!” This prevents these cells from dividing or moving any closer. This is called “contact inhibition.” Contact inhibition blocks cell division even if division signals are being sent. This keeps cells from piling up. This is one thing that can help keep a benign tumor under control. Also, most cells stay in one place. They don’t move around, so at worst, a benign tumor affects only one part of the body. Cancer cells are also susceptible to attack by the immune system. Our body fights off cancerous cells all the time. Finally, cells need a blood supply. This limits the size of most tumors.

But, something can happen that turns a benign cancer malignant. For this to happen, it has to lose its ability to respond to contact inhibition, often will gain the ability to move out into the body (metastasis), becomes less visible to the immune system and gains the ability to attract new blood vessels, establishing a new blood supply. When this happens you have malignant cancer, which can essentially appear anywhere, grow almost anywhere, and grow to any size.

There is some oversimplification in what I just wrote, but by and large this is how cancer works. It is not a single event. Many changes have to occur for a cell to become cancerous, and several more for it to become malignant. Generally, each step along the way is caused by a mutation in the DNA, caused either by random errors in copying the cell’s DNA, or caused by environmental factors like chemicals (carcinogens) and radiation (including sunlight). Anything that damages DNA can cause a mutation. Some mutations interfere with the control mechanisms I describe above and set the cell on its way to becoming cancerous. In some cases, mutations in particular genes are almost always seen in a type of cancer. Some 80% of all pancreatic cancers have a specific mutation in a particular gene called Ras. This mutation convinces the cell that it is ALWAYS receiving a signal telling it to divide. Other cancers, however, seldom have mutations in Ras. Other mutations play the same role. In other cases a particular mutation can be used to predict the severity of a cancer. Mutations in one gene, Her-2/neu, are found in some breast cancer. If it is found, it is a sign that the cancer is likely to be more aggressive and hence requires more aggressive treatment.

Because the breakdown in control of cell division requires mutations, some cancers have genetic components. Breast cancer and colon cancer in particular are associated with mutations in specific genes. Mutations in other genes can lead to an increased chance of getting almost ANY cancer. If you have such a mutation, it doesn’t mean you WILL get cancer, but it means that you are more likely to get cancer. Such mutations are usually in genes that globally help us control cell division or fight off cancer cells. My wife suspects her family has such a mutated gene since several kinds of cancer crop up in her family.

The best way to PREVENT cancer is to not smoke. This alone will greatly reduce your chances of getting cancer, compared with a smoker. Lung cancer is one of the most preventable diseases we know. Very few people will get lung cancer if not exposed to cigarette smoke. Exposure HUGELY increases your chances of getting cancer. The one single best thing you can do for your health is to not smoke.

There is some evidence that other things can help prevent some kinds of cancer. Certain diets seem to reduce the chance of some cancers. Some chemicals are carcinogenic, so exposure to them increases cancer risk. If you live in an area that has a high rate of a particular kind of cancer, chances are there is a genetic link (if most people in the area are related) or there is a chemical around causing cancer. So far no single action you can take can PREVENT cancer as much as not smoking. But general health can improve your body’s ability to fight off cancer, some diets can limit your risk, and avoidance of industrial chemicals can reduce your risk.

But what is probably more effective even than prevention (since we are still only barely aware of what helps prevent) is early detection. Knowing you have a mutation in a gene linked to cancer can help a lot, and increasingly genetic tests are being developed to help detect these mutations. If someone in your family has had cancer, particularly breast or colon cancer, it is well worth looking into such genetic tests. Your risk is the same whether you know or not. But your ability to detect a tumor earlier goes up if you know your risks.

Breast exams and colonoscopies, particularly if someone in your family has had breast or colon cancer, are the best things you can do, other than not smoke and be healthy, to keep from dying of cancer. Both breast cancer and colon cancer are among the most treatable diseases we know…if they are caught early. If not caught early, they become very difficult to cure. Early detection is the main reason cancer survival has gone up so much in recent years. Better tests and better awareness allow doctors to find cancer earlier, meaning treatment can be more effective.

Cancer treatment is all about getting rid of the cancerous cells. Surgery is the most obvious thing: cut out the cancer. That can work well with small benign tumors. The best example is a colon polyp. This is a benign tumor that can be easily removed. If not removed, it can turn malignant and kill you. But sometimes the boundaries between normal tissue and cancer tissue is unclear. And when cancer is malignant, it can be anywhere in the body. A single cancer cell that escapes surgery can re-establish the tumor. This is what happens in most relapses. Somewhere in the body a cancer cell escaped the original treatment.

In addition to surgery there are chemo- and radiation therapies. Both are based on the principle of killing off all fast growing cells in the body. Both mutate DNA. If you mutate DNA enough, the cell can’t divide properly and it dies. Slow growing cells have time to repair their DNA after damage, but fast growing cells don’t. So if you mutate the DNA of all fast growing cells in the body. They die. This includes any cancer cell (you hope) but also includes hair follicles, the lining of the intestine, and our immune cells. This explains most of the side effects of chemo- and radiation therapies. These are crude methods for attacking cancer, but the fact is they work much of the time. Surgery, Chemotherapy and radiation therapy combined with early detection have greatly improved the chances of surviving cancer. HUGE progress has been made, again mostly in the field of early detection.

There are a whole slew of other possible treatments, but most are still uncertain. Since it takes so many mutations to lead to cancer, scientists view each and every one of those problem steps as a potential for treatment. In the past a lab I worked in studied the function of Ras, which, as I said before, is mutated in 80% of pancreatic cancers such that the cancer cells they are always being told to divide. We found ways to interfere with Ras function, and those can give us potential cancer treatments. Some are being used, with limited success, in the clinic. But what has been learned is that cancer often has to be hit with more than one treatment to be stopped. So what scientists are trying to do is find as many ways to hit cancer, even if individually the attacks aren’t so effective, in the hopes that in combination two or three of these treatments will be a powerful way to treat cancer.

Find out your family history of cancer. If there is a history, find out about possible genetic tests and early screening methods to find out your risks. Get informed yourself! Find a doctor who is familiar with the kinds of cancers that run in your family and who is open to finding tests and early screening methods. If a doctor won’t listen to you, find another doctor. Get screened, particularly if you have a family history. Breast and colon exams in particular CAN SAVE YOUR LIFE. If something is detected, do not hesitate to get treatment. Some of the treatments really suck. But believe me, dying of cancer is far, far worse. I have seen it. Getting a colonoscopy is far less horrible than dying of cancer.

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