Cancer is a term used to define an uncontrolled growth of abnormal cells anywhere in the body. There are hundreds of different types of cancers. When the cells start behaving abnormally inside the body they disrupt the normal functioning of body cells. Cancer symptoms may or may not manifest in the early stages – and in some cases – during the advanced stages as well. When symptoms manifest they depend on the specific type and grade of cancer. Some cancers do have certain specific signs and symptoms, but in general the signs and symptoms are not very specific though. However, individuals suffering from cancer may develop fever, lumps, tissue masses, changes in skin colour, change in bladder or bowel function, fatigue, weight loss and unusual bleeding.
What is cancer?
Abnormal cells flourish uncontrollably and in an unprecedented manner. By doing so they can enter any normal body cell or tissues and turn those cells into malignant cells or tumour cells. Therefore, the uncontrolled growth and proliferation of abnormal body cells is termed as cancer. This can start anywhere or in any cell or tissue of the body. When these abnormal cancerous cell infiltrate or spread or become invasive to the surrounding organs or distant organs of the body they become metastatic. Metastatic cancers can be life-threatening. Cancers are identified by the name of the tissue from where the abnormal cancerous cells originated – for instance – lung cancer, breast cancer, oral cancer, colon cancer, stomach cancer, liver cancer, bladder cancer, kidney cancer, prostate cancer, cervical cancer, ovarian cancer, and so on.
The most common cancers in men, women and children in India are as follows:
Women: Breast, Cervical and colorectal cancer
Men: Oral cancer, Lung cancer, prostate cancer, stomach and colorectal cancer
Children: Brain tumour, leukaemia, lymphoma
The incidences of cancers and the types of cancer are influenced by many factors including gender, age, diet, environmental factors, race and genetics – genetic makeup. Therefore, cancer types and incidences of cancers vary depending on these variable factors. Whatever may be the cause of cancer, according to a report from WHO – cancer is the leading cause of deaths across the world – and among the cancer-related deaths, lung cancer, colon cancer, breast cancer, liver cancer and stomach cancer cause most cancer deaths each year. This projection is poised to increase in the future.
What causes cancer?
Anything that is capable of turning a normal body cell into abnormal can potentially cause cancer. Therefore, there are many causes or factors that can lead to cancer growth and development. In addition, there are some unknown causes while some types of cancers are due to lifestyle or environmental factors – and some cancer can develop due to one or more known cause – yet some other may develop owing to personal genetic make-up and strong family history. Some individuals may develop cancer due to a combination of one or more of these factors. Though it is impossible to determine the starting events that cause the development of cancer in an individual, yet several research studies have identified several likely causes that alone or in combination with other causes can lead to cancer. The following are the likely causes, but not all inclusive:
Exposure to chemical or toxic substances: Cigarette smoke contains known cancer-causing carcinogens that cause cancer. In addition, nickel, asbestos, benzene, tobacco, N-nitrosamines, benzidine, vinyl chloride and cadmium are the other cancer-causing chemicals.
Radiations from X-ray emitting devices and other ionizing radiations like beta, gamma, alpha, radon, UV from sunlight can cause cancer.
There are several cancers that have been linked to genes including ovarian, breast, colorectal, skin and prostate cancers.
Some viruses have been potentially linked to cancer – such as hepatitis B & C viruses, Human Papilloma virus (HPV), Epstein-Barr virus and polyomavirus.
Helicobacter pylori and parasite Schistosoma sp. Are being studied as potential cancer-causing agents.
What are the risk factors for cancer?
Age, lifestyle, exposure to chemicals, tobacco usage, certain bacterial and viral infections, exposure to ionizing radiations, exposure to cancer-causing substances in the environment, immunosuppression, some hormones, excessive alcohol consumption, sedentary lifestyle, inadequate or poor diet, genetic make-up and a strong family history and obesity are the risk factors for cancer.