Cancer is a generic term for a large group of diseases that can affect any part of the body. Other terms used are malignant tumours and neoplasms. One defining feature of cancer is the rapid creation of abnormal cells that grow beyond their usual boundaries, and which can then invade adjoining parts of the body and spread to other organs; the latter process is referred to as metastasis. Widespread metastases are the primary cause of death from cancer.
The problem
Cancer is a leading cause of death worldwide, accounting for nearly 10 million deaths in 2020 (1). The most common in 2020 (in terms of new cases of cancer) were:
breast (2.26 million cases);
lung (2.21 million cases);
colon and rectum (1.93 million cases);
prostate (1.41 million cases);
skin (non-melanoma) (1.20 million cases); and
stomach (1.09 million cases).
The most common causes of cancer death in 2020 were:
lung (1.80 million deaths);
colon and rectum (916 000 deaths);
liver (830 000 deaths);
stomach (769 000 deaths); and
breast (685 000 deaths).
Each year, approximately 400 000 children develop cancer. The most common cancers vary between countries. Cervical cancer is the most common in 23 countries.
