Cancer is a group of diseases characterized by the uncontrolled growth and spreadof abnormal cells. If the spread is not controlled, it can result in death. Cancer is causedby external factors, such as tobacco, infectious organisms, and an unhealthy diet, andinternal factors, such as inherited genetic mutations, hormones, and immune conditions.These factors may act together or in sequence to cause cancer. Ten or more years oftenpass between exposure to external factors and detectable cancer.Worldwide, one in seven deaths is due to cancer; cancer causes more deaths thanAIDS, tuberculosis, and malaria combined. When countries are grouped according toincome, cancer is the second leading cause of death in high-income countries withcardiovascular diseases and the third leading cause of death in low and middle-incomecountries with cardiovascular diseases and infectious and parasitic diseases. According toestimates from the International Agency for Research on Cancer (IARC), there were 14.1million new cancer cases in 2012 worldwide, of which 8 million occurred in economicallydeveloping countries, which contain about 82% of the world's population.