Cancer is an abnormal increase in the number of cells that build up
But sometimes, due to some unknown reasons, either the old cells continue to grow beyond their normal life span or there is an uncontrolled production of new cells. In either case, there is a surplus in the number of cells. This accumulation of extra cells results in a ‘tumor’.
Tumors can be either benign or malignant in nature.
A benign tumor normally remains localized and do not regenerate on removal. They are seldom serious.
A malignant tumor, on the other hand, tends to invade the surrounding tissues and may even involve distant organs by spreading through blood or lymphatic chain. It can pose serious danger to life and may recur even after its extraction. It is commonly known as cancer.
Cancers are generally named after the organ from which they originate like colon cancer, breast cancer, lung cancer, etc. When a cancer spreads to other organs, the process is known as metastasis. The original site of cancer is called the ‘primary’, while the subsequently invaded sites are called the ‘secondaries’.
Factors associated with the development of cancer
There are several factors known as the risk factors which are commonly associated with the development of cancer. They are:
- Ageing: Though cancer can be found in people of all age groups, the overall incidence markedly increases after the age of 65.
- Use of Tobacco: Regular use of tobacco and its products has been associated with several different types of cancers like those of mouth, larynx, lungs, bladder, kidneys, cervix, etc. Smoking has been held responsible for more than 180,000 deaths annually in the US alone.
- Ionizing radiations: Exposure to ionizing radiations, either accidentally, as in case of mining or radioactive leak from a nuclear plant or deliberately, as in case of radiotherapy, cause cell damage and increase the chances of cancers of lungs, breasts, stomach and blood (leukemia).
- Microscopic organisms: Many viruses and bacteria have been implicated for cancer. Some of the examples are Epstein Barr virus with lymphoma, Human Herpes virus 8 with Kaposi’s sarcoma, Human Papilloma virus with cervical cancer, Helicobacter Pylori with cancer of stomach, etc.
- Family history: Some cancers like those of breast, ovary, prostate, etc are found more commonly in successive generations. This can be because f the inheritance of a mutated gene or because of common environmental factors.
- Sunrays: Excessive exposure to the harmful ultraviolet radiations in the sunrays can lead to the development of skin cancer.
- Chemicals: Constant exposure to certain chemicals like asbestos, benzene, cadmium and nickel may lead to development of cancer. This is more of an industrial hazard.
- Hormones: Certain hormones like those used in the treatment of perimenopausal symptoms have been associated with increased incidence of breast cancer.
- Diet: Overweight people or those consuming a diet that is rich in fats run a risk of developing cancers of breast, colon, prostate and uterus.
- Alcohol: Excessive alcohol consumption over a long period of time has been associated with cancer of liver, stomach and esophagus.
Awareness about these risk factors results in more and more people avoiding them wherever possible. Certain risk factors like family history cannot be avoided, but then risk factors like smoking, exposure to chemicals and ionizing radiations can definitely be controlled. This increased awareness has resulted in a mark decrease in the number of cancer deaths in the new millennium. Deaths due to lung cancer have reduced by 21% among men and 12% among women due to drop in smoking rates, besides early recognition and management. Moreover, the knowledge about the risk factors has resulted in the development of a number of screening tests. People exposed to the risk factors can undertake these tests so that the cancer can be detected at a very early stage where it is possible to cure it completely. Some of these screening tests are:
- Mammography: It is normally advised once every two years for women above the age of forty but can be advised earlier for those who have a more than normal risk of developing breast cancer. Newer techniques like digital mammography and magnetic resonance imaging (MRI) help in earlier detection of suspicious growths in such patients. As compared to traditional mammography, digital mammography is better in females having dense breast tissue and in perimenopausal women.
- Colonoscopy, sigmoidoscopy, double contrast barium enema and testing for fecal occult blood after the age of fifty are some of the screening methods to rule out polyps and inflammatory bowel disease, conditions that may lead to cancer of the colon. This screening is done after the age of forty in case the person has a family history or is exposed to other risks associated with the disease. Researches are being done to develop drugs that help in the reduction of the polyps. Dietary components like calcium and vitamin D are being looked upon as an alternative to polyp preventing drugs and their exact mechanism of action is being studied. Virtual colonoscopy, which gives a three dimensional view of the colon in a non invasive manner, is a new development. As compared to ten years back, now there are almost six to seven approved drugs for the treatment of colon cancer. This has lead to better life expectancy in patients of this form of cancer. There has been a fall in the number of new case detected by at least 3% in men and 2.2% in women between 2001 and 2006.
- PAP smears are advised for women every three years after they are twenty one years old or after they have become sexually active, to rule out cervical cancer. Newer techniques like using fluid-based monolayers (ThinPrep, CytoRich), Automated cytological testing (Pap Net, Auto Pap 300 QC) and Human papillomavirus deoxyribonucleic acid testing by Hybrid Capture have vastly improved upon the specificity of the screening test.
Decoding of the human genome and its sequencing has opened up new frontiers in linking certain gene patterns with some aggressive forms of cancers which regenerate quickly and metastasize far and wide. Bone marrow or stem cell replacement therapy has revolutionized the cancer treatment. Here, the bone marrow is extracted before chemotherapy and then re-implanted and re-stimulated using medicines called as colony stimulating factors so that the patient’s immune system is hardly compromised. This enables the patient to undergo more cycles of chemotherapy thereby increasing the chances of eliminating the cancer. Invention of surgical techniques, like the gamma knife have offered scope for previously inoperable brain growths.
Thus, we can conclude that we have entered an exciting phase in the treatment of cancer in the new millennium where novel methods of cancer prevention and its treatment are being discovered everyday.