Cancer is a disease in which some of the body cells grow uncontrollably and spread to other parts of the body. Cancer can start almost anywhere in the human body. Normally, human cells grow and multiply (through a process called cell division) to form new cells as the body needs them. When cells grow old or become damaged, they die, and new cells take their place. Sometimes this orderly process breaks down, and abnormal or damaged cells grow and multiply when they shouldn’t. These cells may form tumours, which are lumps of tissue. Cancerous tumours spread into, or invade, nearby tissues and can travel to distant places in the body to form new tumours. This process is called metastasis.
For further information, please refer the following websites
https://www.cancer.gov/
https://www.cancerresearchuk.org/about-cancer/
https://main.mohfw.gov.in/sites/default/files/3651434918nccp4_0.pdf
https://gco.iarc.fr/en
https://www.iarc.who.int/