ABSTRACT
In this review, epidemiological, physiological, pathophysiological and pharmacological themes of cancer are dealt. So far, there are over 200types of cancers, which are linked to six key events that collectively lead to the formation of a malignance: self-sufficiency in growth signals, insensitivity to growth inhibitory signals, evasion of apoptosis, unlimited replication potential, sustained angiogenesis and invasion and metastasis. These six capabilities are possibly shared by most human tumors. In2000, there were 10 million new cancer cases and 6 million cancer deaths worldwide. According to estimates by the American Cancer Society, the disease produced approximately 556,000 deaths in 2003, corresponding to 1,500 deaths from cancer every day in America. Annually, in Chile, cancer is responsible for 23 percent of all deaths, constituting the second leading cause of death after cardiovascular diseases. They have identified several risk factors for cancer such as smoking, chronic infections, alcohol consumption, reproductive factors, hormone replacement therapy, dietary habits, sunlight, among others. These factors may cause multiple genetic alterations that involve activation of several oncogenes and the loss of two or more suppressor genes, but not a single change will lead to the formation of a neoplasm. The Knowledge of the molecular differences between normal and malignant cells could be used to target specific pathways and receptors of the latter, thus preventing normal cell death.