Cancer is not one disease but more than two hundred in all. Just enumerating all the different types of cancers can take up all the space I have available for this article. As such writing about cancer in a short format might seem a bit fruitless. My purpose today is to talk of general principles and some common concepts.
First, why is cancer called cancer. Early physicians that described malignant tumours found that when cut open, the cancerous tissue spread out in the normal tissues like a crab. Hence the name cancer for such tumours.
What causes cancer? At the very basic, all the cells in the human body are programmed to divide into new cells and those cells that are defective die a normal death. Some cells, however, become abnormal and refuse to die. The defense mechanism in the body identifies such cells and kills them. The production of such abnormal cells and their destruction by the body is a normal and ongoing process. Occasionally, something upsets this balance and these abnormal cells keep on multiplying and replacing normal cells in a particular part of the body (organ) and eventually spreading all over the body. If unchecked, this process replaces and kills enough normal cells in the body and finally kills the person.
Before tackling some of the reasons why the abnormal cancer cells become dominant in a body system or a body organ let me first make one very basic statement/observation. Not all cancers will kill even if left untreated. Why? Because some cancers are very slow growing and by the time they become big enough to cause problems, the person might be dead from something else. One important example is cancer of the prostate gland in men. This cancer when found in older men often might not need to be treated because it is unlikely to kill and also because the treatments are frequently more unpleasant than the disease itself.
So now to what causes cancers. Most cancers are probably due to unknown factors or what might be called pure chance. This fact is often understated by cancer doctors (oncologists) since most of them want to stress certain aspects of lifestyle and behaviour that they think of as cancer producing. Some are well known. Smoking increases the chance of getting lung cancer but then all smokers do not get lung cancer. Similarly, many foods are also blamed as is alcohol. Obesity is another frequently mentioned factor that increases the risk of developing cancer. The list of possible risk factors is long and keeps on getting longer.
There are four risk factors that indeed contribute to development of cancer. First are hereditary factors, then exposure to known carcinogens (cancer producing substances) like smoking, asbestos and other environmental pollutants, then we have radiation and finally different viruses. Here again all of these factors increase the risk of particular cancers but do not inevitably lead to cancer. Other than hereditary factors, exposure to most carcinogens can be avoided or in case of certain viruses, an infection can be prevented by appropriate vaccination.
However, there are three types of cancer that could be generally preventable at this time. First of course is Liver Cancer. The three most common reasons for developing this cancer are Hepatitis B and C and alcoholic cirrhosis (liver damage). Hepatitis B is preventable with appropriate vaccination, Hepatitis C is preventable with appropriate public health measures but most importantly at the present time if detected before liver damage and cancer occurs, it is quite treatable and almost for once curable. Damage to the liver due to alcohol excess is obviously preventable.
As it is, a major effort is being made in the Punjab to detect early hepatitis and to treat it and also develop liver transplant centres to treat end stage liver disease leading to liver cancer. The problem with liver damage as well as Hepatitis B and C is that it is rarely detectable unless too far advanced. And at the present time it is estimated that anywhere between five and fifteen per cent of the population in certain areas of the Punjab might already have Hepatitis C.
The other preventable cause of cancer involving the cervix of the uterus is due to infection with the Human Papilloma Virus. A vaccination to prevent this infection exists and young women are being advised in the United States to get this vaccination. And in other cases of cancer of the cervix, routine PAP test (scraping from the cervix during a routine examination) can catch cancer early enough to be essentially curable with surgery.
The third type of preventable cancer is the one that is due to an inherited tendency. Of the best known inherited causes of cancer are the BRCA1 and BRCA2 genes. Women with these genes have a very high chance of developing breast and ovarian cancer. The risk can be as high as five or six out of ten. Such women may seek a ‘prophylactic’ (preventive) removal of both breasts, an operation that the famous actress Angelina Jolie went through recently. With advances in genetics it is possible that in a few decades most inherited tendencies for cancer will be discovered and possibly treated even before the child is born.
One cancer that is of importance in the context of preventability is lung cancer. The relationship between smoking cigarettes and developing lung cancer is pretty well established. However, in my opinion rather than cancer, the damage done to the lungs from smoking is much more common and also quite dangerous leading to what is called Chronic Obstructive Pulmonary Disease (COPD).
Before any discussion about treatment, a few words about detection. Early detection of most cancers facilitates better treatment. Many different ‘routine’ tests and procedures for early detection of cancers have been proposed and recommended. These include blood tests for different types of hepatitis, mammography (special X-Rays) for detection of early breast cancer, colonoscopy (a look inside the large bowel) to identify and remove ‘polyps’ (small, usually non-cancerous growths). Most cancers of the colon are thought to arise from polyps. Then there is the often excessively used blood (PSA) test for cancer of the prostate gland.
Most localised types of cancer, if detected early, can be successfully removed through surgery. However, one of the more important developments in the treatment of most cancers is the realisation that cancer is not just a localised disease. For this reason, surgery is usually supplemented with medicines that kill cancer cells and radiation that kills cancer cells in a localised area.
The use of medicines to kill cancer cells is called ‘chemotherapy’. Generalised cancers like those of the blood are primarily treated with chemotherapy and or radiation. Newer ‘targeted’ methods are being developed using novel drugs that are specific to a particular person and a particular cancer. Another area of major research is in the ways to improve the human immune system that normally fights cancer.
Over the last few decades with advances in medical treatment of cancer, extensive and deforming surgery has become quite rare. This is most evident in treatment for breast cancer where the ‘radical mastectomy operation’ is now only of historical interest.