Cancer and Evolution by Natural Selection
Cancer is a disease that starts in cells, the body’s basic units of life. Normally, cells grow and divide to make more cells as needed to keep the body healthy. But sometimes these cells can become abnormal and keep growing without control. They may also spread to other parts of the body.
Cancers can start in many different types of cells, including tissue or skin cells and cells that line organs and create blood vessels. But they can also start in stem cells, which are located in bone marrow and make blood cells. Cancers that start in stem cells can eventually form a mass of abnormal blood cells called leukemia.
All cancers start when some genes that control cell growth and death are mutated. Most gene mutations happen before you’re born, and others develop throughout your life due to things like smoking, sun exposure, cancer-causing chemicals (carcinogens) and other factors. Mutations can change how a gene functions or stop it from functioning at all. When enough genes change, the cell can’t repair itself and becomes cancerous.
Normal cells are designed to survive and pass on their traits (including growth and survival characteristics) to new cells that will replace them. But as the population of cells grows, there is selection pressure to promote individuals with certain traits that are better adapted to their environment and more likely to reproduce and pass on their advantageous characteristics to future generations. This is referred to as evolution by natural selection.
The selection pressures that can drive cancer progression include the ability to evade apoptosis, to resist growth inhibitors and cytokines, and to attract and trick immune cells. In addition, the microenvironment of a tumor can provide selection pressures that favor cells with certain features such as the ability to promote angiogenesis and invasion and to avoid opportunistic infection and inflammatory response.
If these conditions are met, the cancer cells can continue to evolve until they have a lethal phenotype. All of the processes and features that characterize evolution by natural selection – heritable variation, a struggle for existence and variations influencing this struggle – are evident in cancer. Over time, the accumulation of these inherited and acquired mutations in cancer cells leads to the development of a malignant phenotype that is increasingly able to thrive and spread despite treatment. This is how cancers progress from a benign to lethal phenotype and kill people. Fortunately, there are steps that you can take to help prevent cancers from developing. See your healthcare provider for regular screenings, such as colonoscopies and mammograms, to find them early when they’re most treatable. And protect your skin with sunscreen when going outdoors. You can also reduce your risk by maintaining a healthy weight, not smoking and getting plenty of exercise.
Cancer is a disease that starts in cells, the body’s basic units of life. Normally, cells grow and divide to make more cells as needed to keep the body healthy. But sometimes these cells can become abnormal and keep growing without control. They may also spread to other parts of the body. Cancers can start in many different types of cells, including tissue or skin cells and cells that line organs and create blood vessels. But they can also start in stem cells, which are located in bone marrow and make blood cells. Cancers that start in stem cells can eventually form a mass of abnormal blood cells called leukemia. All cancers start when some genes that control cell growth and death are mutated. Most gene mutations happen before you’re born, and others develop throughout your life due to things like smoking, sun exposure, cancer-causing chemicals (carcinogens) and other factors. Mutations can change how a gene functions or stop it from functioning at all. When enough genes change, the cell can’t repair itself and becomes cancerous. Normal cells are designed to survive and pass on their traits (including growth and survival characteristics) to new cells that will replace them. But as the population of cells grows, there is selection pressure to promote individuals with certain traits that are better adapted to their environment and more likely to reproduce and pass on their advantageous characteristics to future generations. This is referred to as evolution by natural selection. The selection pressures that can drive cancer progression include the ability to evade apoptosis, to resist growth inhibitors and cytokines, and to attract and trick immune cells. In addition, the microenvironment of a tumor can provide selection pressures that favor cells with certain features such as the ability to promote angiogenesis and invasion and to avoid opportunistic infection and inflammatory response. If these conditions are met, the cancer cells can continue to evolve until they have a lethal phenotype. All of the processes and features that characterize evolution by natural selection – heritable variation, a struggle for existence and variations influencing this struggle – are evident in cancer. Over time, the accumulation of these inherited and acquired mutations in cancer cells leads to the development of a malignant phenotype that is increasingly able to thrive and spread despite treatment. This is how cancers progress from a benign to lethal phenotype and kill people. Fortunately, there are steps that you can take to help prevent cancers from developing. See your healthcare provider for regular screenings, such as colonoscopies and mammograms, to find them early when they’re most treatable. And protect your skin with sunscreen when going outdoors. You can also reduce your risk by maintaining a healthy weight, not smoking and getting plenty of exercise.