An abnormal growth of cells which tend to proliferate in an uncontrolled way and, in some cases, to metastasize (spread).
Cancer can involve any tissue of the body and have many different forms in each body area. Most cancers are named for the type of cell or organ in which they start. If a cancer spreads (metastasizes), the new tumour bears the same name as the original (primary) tumour.
Cancer is ultimately the result of cells that uncontrollably grow and do not die. Normal cells in the body follow an orderly path of growth, division, and death. Programmed cell death is called apoptosis, and when this process breaks down, cancer begins to form. Unlike regular cells, cancer cells do not experience programmatic death and instead continue to grow and divide. This leads to a mass of abnormal cells that grows out of control.
Cancer is a group of diseases that can cause almost any sign or symptom. The signs and symptoms will depend on where the cancer is, how big it is, and how much it affects the organs or tissues. If a cancer has spread (metastasized), signs or symptoms may appear in different parts of the body.
As a cancer grows, it can begin to push on nearby organs, blood vessels, and nerves. This pressure causes some of the signs and symptoms of cancer. If the cancer is in a critical area, such as certain parts of the brain, even the smallest tumour can cause symptoms.
Some common symptoms that may occur with cancer are as follows:
Persistent cough or blood-tinged saliva
These symptoms usually represent simple infections such as bronchitis or sinusitis.
They could be symptoms of cancer of the lung, head, and neck. Anyone with a nagging cough that lasts more than a month or with blood in the mucus that is coughed up should see a doctor.
A change in bowel habits
Most changes in bowel habits are related to your diet and fluid intake.
Doctors sometimes see pencil-thin stools with colon cancer.
Occasionally, cancer exhibits continuous diarrhoea.
Some people with cancer feel as if they need to have a bowel movement and still feel that way after they have had a bowel movement. If any of these abnormal bowel complaints last more than a few days, they require evaluation.
A significant change in bowel habits that cannot be easily explained by dietary changes needs to be evaluated.
Blood in the stool
A doctor always should investigate blood in your stool.
Hemorrhoids frequently cause rectal bleeding, but because hemorrhoids are so common, they may exist with cancer. Therefore, even when you have hemorrhoids, you should have a doctor examine your entire intestinal tract when you have blood in your bowel movements.
With some individuals, X-ray studies may be enough to clarify a diagnosis.
Colonoscopy is usually recommended. Routine colonoscopy, even without symptoms, is recommended once you are 50 years old.
Sometimes when the source of bleeding is entirely clear (for example, recurrent ulcers), these studies may not be needed.
Unexplained anaemia (low blood count).