Cancer refers to a group of diseases caused by uncontrolled growth and spread of abnormal cells in any organ of the body. They are also called malignant tumors or neoplasms. This disease is characterized by the rapid increase in abnormal cells which invade other organ systems outside their boundaries in a process called metastasis. This is the major cause of death in cancer. They are related to genetic factors as well as environmental factors such as ultraviolet and ionizing radiation, chemical carcinogens and certain types of bacterial, viral and parasitic infections.

Worldwide, cancer is one of the leading causes of death. Cancer ranks as the number one cause of death in developed nations and second in developing nations. In 2012 alone, there were 8.2 million deaths from cancer. The top five types of cancer with the highest mortality rates are: lung cancer, liver cancer, stomach cancer, colorectal cancer and breast cancer.

In developed countries, the top three causes of cancer deaths among men are: lung cancer, colorectal cancer and prostate cancer. In women, the leading cause of death is breast cancer, followed by lung and colorectal cancer. Different trends are seen developing nations. In men, the top three causes of cancer deaths are lung cancer, liver cancer and stomach cancer. In women, these are breast cancer, cervical cancer and lung cancer.

Certain modifiable determinants account for 30% of cancer deaths including obesity, poor diet, lack of exercise, smoking and alcohol use. Smoking is related to 20% of cancer deaths worldwide, and causes 70% of all lung cancer deaths.

Although the incidence of cancer is lower in developing countries, they account for a larger percentage of cancer deaths worldwide. In 2008, 72% of cancer deaths were from low to middle income countries. This is due to lower survival rates caused by poor accessibility to optimal health care. For instance, of the 275,000 women who die annually from cervical cancer, more than 85% are from developing nations.

This disparity is notable even in palliative care. More than 99% of untreated and painful deaths from cancer occur in the developing world. In these countries, many patients diagnosed with cancer are sent home untreated without the benefit of palliative relief.

Due to the aging global population, it is estimated that many non communicable diseases including cancer will rise over the next 30 years.