I thought I might go over a few concepts of cancer therapies for those of you who are interested but might not have the background to make sense of some of it.
Surgery: If surgery for the cancer can be done it will. Surgery is often curative (long-term survival with the cancer or with the complete absence of the cancer). Surgery refers to the complete removal of the tumor and it is usually performed when the cancer is well-defined (like a solid tumor) and works well with cancers that are caught early. Some cancers are small but located in areas that the surgeon may not have access to (like parts of the brain stem, parts of the spinal column, or even near some major arteries, etc.). If the surgery might end up killing the patients, then it is not performed. If the patient is very old or has heart conditions, the surgery for cancer removal might not be performed as well.
Radiation therapy: high energy frequencies that are directed at the cancer with hopes of ‘burning it off’ and causing the tumor and surrounding tissue to die. Better and better forms of radiation therapy are available in some centers that allow for more accurate focusing on the beam of energy to the tumor and not the healthy tissue. Not all cancers are radio-sensitive. Radiation has several side effects and too much radiation damage can also lead to cancer down the road….so killing one cancer but inducing another is not a good idea. Sometimes the addition of radiation therapy to surgery can help kill off any remaining cells that were not removed during the operation. Many times radiation is not a one time deal, but must be performed numerous times and the patient must come back to the hospital for all the cycles.
Chemotherapy: There are many kinds. In essence, they are drugs that kill cells that rapidly divide. Cancer cells rapidly divide and thus are usually very sensitive to this form of therapy. Many types of chemotherapies are used against many types of cancers including solid and liquid cancers (or blood cancers). These types of agents can kill cells directly, poison them so they can’t make DNA, stop them from cycling (a terms used to describe the process of cell division), starve them from nutrients, or prevent their DNA repair machinery from working, etc. These agents have a lot of side effects as they almost always target other cells that divide in your body in addition to the cancer cells. For example, they target hair follicles (and the hair will fall out) or they hit the cells lining the gut which turn over quickly and cause patients to vomit severely sometimes. Some patients can be on several of these drugs at a time and often they are combined with surgery and/or radiation therapy. These are not fun to take, but in some cases they do help to reduce the cancer to a very small size and allow patients to live longer. However, many people who get treatment with chemotherapy do see their cancers come back after some time and thus it is not curative in most cases.
Transplantation: One can have the entire organ transplanted if it has cancer or one can get a type of blood transplant know as a hematopoetic cell transplant. In the latter case, the patients own bone marrow is killed off using drugs and radiation and then a new bone marrow from another person is given to them. It is a horrific procedure that used to kill many patients and sometimes still does. However, it can be curative and the patient can live cancer free for the rest of his/her life in some cases. There are a lot of complicated things that the doctor must do before performing this kind of procedure and the younger the patient is the better. For some childhood blood cancer, this procedure has been short of a miracle. It is best used when cancer of the immune system are detected. This procedure can cost hundreds of thousands of dollars in some countries and is very dangerous.
Immunotherapy: This is a newer type of therapy and refers to any product of the immune system that is given to patient to help them fight off their cancer. For example, a potentially curative form of this therapy works for a type of skin cancer and renal cell carcinoma. The drug is IL-2 a cytokine or protein mediator that helps activate T cells and these cells then look for and kill the cancer. However, only 10-15% of patients respond to this drug well and most patients do not and subsequently die of their disease. High-dose IL-2 therapy is also very toxic. Another form of this therapy is being used now (just recently developed) on advanced skin cancer and uses another immune molecule called CTLA-4. Blocking this protein seems to enhance T cells to kill the patients own cancer cells. Again, this only works well in a small fraction of people with this type of skin cancer. Many other forms of this therapy are being tested now and it is hoped that this is one way that some cancers may be cured in the future, but honestly we are quite far from that at the moment. These drugs cost a huge amount and are not very well tolerated by many patients (too many side effects). They also try to use the patients of immune system and thus can cause other damage in many cases.
Targeted or Individualized therapy: This is a large and new area of development in the anti-cancer arena. Here patient as well as cancer specific molecules are attacked by certain drugs that recognize them. The most well-known example of this is a drug called Gleevec(Tm) that is used for the treatment of a blood cancer called CML. It targets a very specific cancer protein that only affects the CML cancer cell. The drug basically poisons this cancer protein and kills the cancer cell. It needs to be taken for life and can be very expensive. The other problem is that about 15% of all patients develop resistance to the drug (or rather the cancer cell changes before it is all killed and starts to make a protein that does not bind the drug). A very new example is used with some success against advanced skin cancer to target a very common mutation in a protein that is essential for the cancer cell to grow. So a drug is used to bind to that very specific mutation (50% of all patients with advanced skin cancers have this mutation present) can block this survival factor for the cancer cell and it is then killed. Many new proteins are being targeted such as those that cancer cells use to get blood supply, allow the cancer to move to different areas in the body, and so on. In all the cases, these drugs are aimed at blocking these things that the cancer cell need to survive. In many cases, these are unique to the cancer cells and not to the normal cells in the body.
Unique category: The last type of therapy I wish to discuss is a rare but successful type of anti cancer drug known as a vaccine immunization type. For bladder cancer there is a drug that is injected into the area of the bladder…the drug is actually the same thing that is used to vaccinate children and some adults for tuberculosis: BCG. Intrathecal BCG (or intravesical) works very well in about 50-60% of patients with early stage bladder cancer. It works by stimulating the immune response against the cancer, but besides that we do not know much about the mechanism. It is one of the most successful drug therapies used today for cancer….but no one really understands it and it does not seem to work well against other cancers.
There are other examples, but the most common ones have been mentioned. I hope you have found this information useful. I kept it general and vague intentionally. I know that some of you may be looking for more specific information and want more detail. Do ask me if you want more information or do check out some of the additional resources that I have one my web page.
Thanks D C – Cancer Made Simple