Understanding the Cancer Process
Cancer is a disease in which abnormal cells develop and grow uncontrollably throughout the body. This growth and spread can disrupt normal tissue functions and co-opt and kill noncancerous cells, resulting in pain, loss of function, and death. It also causes a great deal of stress and emotional upheaval in those who suffer from it, and is responsible for the deaths of about 10 million people each year worldwide.
What makes cancer so difficult to understand and treat is the fact that it is a complex process. It is a disease that occurs in multicellular organisms and arises from long runs of cell division in which certain genes get mutated. Cancer cells have a different genetic code than the cells from which they originated and have mutations in a variety of other genes that influence their normal functions, such as growth control, proliferation, and cell death.
Because of these changes, cancer cells no longer respond to the signals that normally regulate cell growth and cell death. This allows the cancer cells to proliferate and accumulate more and more mutations over time, which creates a series of progressively more malignant phenotypes. Each of these phenotypes is adapted to fill a particular ecological niche in the tumor and, in turn, influences cancer progression and therapeutic resistance.
As a consequence, natural selection acts upon cancer cells and selects for those with advantageous traits, such as greater capacity to survive or reproduce, promotion of angiogenesis, evasion of the immune system, and resistance to cell death. This selection results in increased frequencies of the phenotypes and eventually in the formation of new phenotypes that contribute to tumor progression, drug resistance, and metastasis.
Cancer cells are constantly competing with each other, as well as with normal noncancerous cells and with other types of tumors. This competition drives a selection for cells that are better able to take up nutrients, promote angiogenesis, resist apoptosis, and invade other parts of the body. It also favors those that can evade the immune system and co-opt normal noncancerous cells.
When a person is diagnosed with cancer, tests are done to see how big the cancer is and whether it has spread from where it started in the body (its stage). This information helps doctors decide what treatment may be best for the patient.
Until recently, scientists knew little about the origin of cancer. They knew that cancer cells were very different from normal cells, but they did not know how a person could get cancer or what caused it to start. Scientists also understood that viruses, chemicals, radiation, and even some infections might trigger cancer, but they did not know what happened inside the body to cause this change. What they did learn was that cancer starts when one or more genes become mutated and that most, if not all, human cancers are monoclonal, meaning that all the cancer cells in a tumor have come from the same initial mutationed cell.
Cancer is a disease in which abnormal cells develop and grow uncontrollably throughout the body. This growth and spread can disrupt normal tissue functions and co-opt and kill noncancerous cells, resulting in pain, loss of function, and death. It also causes a great deal of stress and emotional upheaval in those who suffer from it, and is responsible for the deaths of about 10 million people each year worldwide. What makes cancer so difficult to understand and treat is the fact that it is a complex process. It is a disease that occurs in multicellular organisms and arises from long runs of cell division in which certain genes get mutated. Cancer cells have a different genetic code than the cells from which they originated and have mutations in a variety of other genes that influence their normal functions, such as growth control, proliferation, and cell death. Because of these changes, cancer cells no longer respond to the signals that normally regulate cell growth and cell death. This allows the cancer cells to proliferate and accumulate more and more mutations over time, which creates a series of progressively more malignant phenotypes. Each of these phenotypes is adapted to fill a particular ecological niche in the tumor and, in turn, influences cancer progression and therapeutic resistance. As a consequence, natural selection acts upon cancer cells and selects for those with advantageous traits, such as greater capacity to survive or reproduce, promotion of angiogenesis, evasion of the immune system, and resistance to cell death. This selection results in increased frequencies of the phenotypes and eventually in the formation of new phenotypes that contribute to tumor progression, drug resistance, and metastasis. Cancer cells are constantly competing with each other, as well as with normal noncancerous cells and with other types of tumors. This competition drives a selection for cells that are better able to take up nutrients, promote angiogenesis, resist apoptosis, and invade other parts of the body. It also favors those that can evade the immune system and co-opt normal noncancerous cells. When a person is diagnosed with cancer, tests are done to see how big the cancer is and whether it has spread from where it started in the body (its stage). This information helps doctors decide what treatment may be best for the patient. Until recently, scientists knew little about the origin of cancer. They knew that cancer cells were very different from normal cells, but they did not know how a person could get cancer or what caused it to start. Scientists also understood that viruses, chemicals, radiation, and even some infections might trigger cancer, but they did not know what happened inside the body to cause this change. What they did learn was that cancer starts when one or more genes become mutated and that most, if not all, human cancers are monoclonal, meaning that all the cancer cells in a tumor have come from the same initial mutationed cell.