Cancer is now the world’s biggest killer; fourteen (14) million new cases were reported globally in 2012.
In the same year, 8.2 million persons died globally of cancer. Of these deaths, it is said that 3.7million could have been prevented. Additional causes of cancer are discussed below:-
Most forms of radiation if not all can cause cancer, from medical x-rays to radio-pharmaceuticals. Even solar radiation is said to damage DNA and inactivate tumor suppressor gene leading to cancer – especially skin cancer. Exposure to high dose of various forms of radiation increases risk of leukaemia five –fold.
Certain drugs used in the treatment of cancer can cause cancer in other locations. Also drugs used to suppress rejection of foreign bodies and some anti-hormone drugs have also been found to cause cancer.
Some chronic infections are associated with cancer. It is said that about 25% of all cancers in developing countries can be traced to chronic infections. Such infections include – Hepatitis B and Hepatitis C (associated with liver cancer), Human Papilloma Virus infection (associated with cancer of the cervix) and Helicobacter Pylori Infection (associated with stomach cancer). About 30 – 40% of HIV patients end up with cancer.
Drugs used to prevent the body from rejecting transplants can cause cancers. Some viruses are also implicated in this and they rarely affects persons who are not immuno-suppressed. A person’s immunity can also be suppressed by certain viruses like HIV, and the Human Papilloma Virus (HPV).
About 5 percent of all cancers are attributed to heredity. This could be due to a change in the sperm or ovum before fertilization. Thus cancers are known to run in families- such as breast cancer, prostate cancer and colon cancer.
Studies have even gone far enough to identify the particular genes involved in these cancers.
6.Reproductive factor and Hormones
Risk of breast cancer depends to an extent on use of oestrogen hormone. Long use (above 5 years) of oestrogen replacement therapy in post menopausal women increases risk of cancer of the breas; same with high levels of male hormones in post menopausal women. Some hormones are also associated with cancers of prostate, endometrium, colon and lungs.