After more than 3 decades of Medical Oncology practice, now I am firmly convinced about the importance of cancer prevention.
We cure a very small percentage of cancer patients and in others it is at its best a prolongation of useful life. Even when we achieve cure it is many times at a great financial and organ loss. In general the popular notion that cancer is the greatest misfortune that can descend on man is true.
The only cost effective way of dealing with cancer is to prevent it. Wherever the etiology is firmly known, prevention is possible. Where cause is not known, screening the high risk groups for cancer can detect precancerous conditions or early chances and cure rates can be high. The best person to advise prevention in my opinion is an oncologist who will be in a priviliged position to be in touch with family, friends of a cancer patient, who will be amenable to preventive advice.
At least 40% of cancers are tobacco related and are perfectly preventable. About 30–40% are related to wrong diet,obesity,lack of exercise and wrong sexual practices. These require change of life style and this change also is possible to achieve. Some common cancers are virus induced and vaccination will be the perfect answer for their prevention.
Cancer arises from a loss of normal growth control. In normal tissues, the rates of new cell growth and old cell death are kept in balance. In cancer, this balance is disrupted. This disruption can result from uncontrolled cell growth or loss of a cell’s ability to undergo “apoptosis”. Apoptosis, or “cell suicide,” is the mechanism by which old or damaged cells normally self-destruct.
Cancer can originate almost anywhere in the body. Carcinomas are the most common types of cancer arise from cells that cover the external and internal body surfaces. Sarcomas are the cancers arising from the supporting tissues of the body like bone, cartilage, fat, muscle etc. Lymphomas are cancers that arise from the lymph nodes and tissues in the bodys immune system. Leukemias are cancers of the immature blood cells that grow in the bone marrow and tend to accumulate in the blood stream.
Cancers are capable of spreading through the body by two mechanisms- invasion and metastasis. Invasion refers to the direct migration and penetration by cancer cells into the neighbouring tissues. Metastases refers to the ability of the cancer cells to penetrate into lymphatic and blood vessels, circulate through the blood stream and invade normal tissues elsewhere in the body.
70–75% of the patients are preventable. In the rest 25% many of them can be detected early if screened regularly. Cancers related to tobacco like lung cancers, head and neck cancers, pancreatic cancers, bladder cancer are preventable if the patient does not use tobacco or stops using tobacco. About 30% of the cancers are related to obesity, wrong diet and lack of exercise. These cancers like colon cancer, breast cancer and prostate cancer can be reduced by the right lifestyle intervention.
About 15–20% of cancers are related to infection either a viral infection like HPV, EBV and Hepatitis B and C viruses. Cancer of uterine cervix, liver cancer, some head and neck cancers can be prevented by vaccination against these viruses. Some bacterial infections also can cause cancer as exemplified by stomach cancer and stomach lymphoma caused by H Pylori. Lack of physical exercise can be responsible for 15% of the cancers directly and several other cancers indirectly.
