Cancer is the uncontrolled growth and spread of cells. It can affect any part of the body. The growth often invades surrounding tissue and can metastasize to different sites. Many cancers can be prevented by avoiding exposure to common risks factors, such as tobacco smoke. In addition, a significant proportion can be cured by surgery, radiotherapy or chemotherapy especially if detected early.
Cancer is a leading cause of death worldwide, accounting for 8.2 million deaths in 2012. The most common causes of cancer death are cancers of:
- Lung (1.59 million deaths)
- Liver (745 000 deaths)
- Stomach (723 000 deaths)
- Colorectal (694 000 deaths)
- Breast (521 000 deaths)
- Oesophageal cancer (400 000 deaths)
Cancer figure among the leading causes of morbidity and mortality worldwide, with approximately 14 million new cases and 8.2 million cancer related deaths in 2012. The number of new cases is expected to rise by about 70% over the next 2 decades. Among men, the 5 most common sites of cancer diagnosed in 2012 were lung, prostate, colorectal, stomach, and liver cancer.
Among women, the 5 most common sites diagnosed were breast, colorectal, lung, cervix, and stomach cancer.
Around one third of Cancer deaths are due to the 5 leading behavioural and dietary risks, high body mass index, low fruit and vegetable intake, lack of physical activity, tobacco use, and alcohol use.
Tobacco use is the most important risk factor for cancer causing around 20% of global cancer deaths and around 70% of global lung cancer deaths.
Cancer causing viral infections such as HBV/HCV and HPV are responsible for up to 20% of Cancer deaths in low and middle income countries.
More than 60% of world’s total new annual cases occur in Africa, Asia and Central and South America. These regions account for 70% of the world’s Cancer deaths.
It is expected that annual Cancer cases will rise from 14 million in 2012 to 22, within the next 2 decades.
What causes Cancer?
Cancer arises from one single cell. The transformation from a normal cell into a tumour cell is a multi stage process, a progression from a pre-cancerous lesion to malignant tumours. These changes are a result of the interaction a person’s genetic factors and three categories of external factors, including physical carcinogens, such as ultraviolet and ionizing radiation;
chemical carcinogens, such as asbestos, components of tobacco smoke, aflatoxin (a food contaminant) and arsenic (a drinking water contaminant); and biological carcinogens, such as infections from certain viruses, bacteria or parasites.