The Basics of Cancer
Cancer is a complex and widespread disease, but it all starts as one abnormal cell. A cell is the smallest unit of a living organism, which can be anything from a single-celled bacteria to a multicellular animal such as a human. Cells perform essential biological functions, and are responsible for the creation of new cells and the replacement of old ones. In addition, they form the basis for multicellular structures such as tissues and organs that make up the body, and they also form the basis for an organism’s genetic identity.
Cancer forms when genes that manage a cell’s activity mutate. The mutated genes produce abnormal cells that multiply and spread out of control. They may start in a single tissue, but they can then spread to other parts of the body, where they interfere with normal functions. For example, if a tumor grows in the lungs, it can make it difficult to breathe. Normally, when cells die, they are replaced by healthy cells from the same tissue. But in some cases, the cancerous cells continue to grow and replace normal cells. The resulting mass of abnormal cells is known as a tumor or cancerous growth.
Over time, the mutations that occur in cancer cells accumulate and select for heritable traits. These characteristics give the cells a competitive advantage over normal cells in their tissue. As the population of cancer cells increases, they adapt to their environment by filling specific ecological niches. They develop traits such as faster nutrient uptake, the ability to evade the immune system, and an aggressive phenotype that promotes growth and metastasis.
When a person is diagnosed with cancer, it is often discovered as the result of routine medical tests or when a person seeks treatment for a problem like persistent pain. The early diagnosis of cancer can improve outcomes. If the cancer is confined to the area in which it started, or if it has not spread, treatments can often stop the cancer from returning and help a patient live longer.
Symptoms of cancer can range from very mild to severe and vary from person to person. Common symptoms include fatigue, weight loss, and pain that does not go away. Some people with cancer have blood in their urine or stool, and others may have abnormal skin changes, such as a mole that changes shape or color.
Some types of cancer can be treated with surgery, radiation, or drugs. Many types of cancers can be prevented by avoiding tobacco, maintaining a healthy weight, and getting regular screening exams, including a physical exam and a history of previous health problems.
Cancer is a complex and widespread disease, but it all starts as one abnormal cell. A cell is the smallest unit of a living organism, which can be anything from a single-celled bacteria to a multicellular animal such as a human. Cells perform essential biological functions, and are responsible for the creation of new cells and the replacement of old ones. In addition, they form the basis for multicellular structures such as tissues and organs that make up the body, and they also form the basis for an organism’s genetic identity. Cancer forms when genes that manage a cell’s activity mutate. The mutated genes produce abnormal cells that multiply and spread out of control. They may start in a single tissue, but they can then spread to other parts of the body, where they interfere with normal functions. For example, if a tumor grows in the lungs, it can make it difficult to breathe. Normally, when cells die, they are replaced by healthy cells from the same tissue. But in some cases, the cancerous cells continue to grow and replace normal cells. The resulting mass of abnormal cells is known as a tumor or cancerous growth. Over time, the mutations that occur in cancer cells accumulate and select for heritable traits. These characteristics give the cells a competitive advantage over normal cells in their tissue. As the population of cancer cells increases, they adapt to their environment by filling specific ecological niches. They develop traits such as faster nutrient uptake, the ability to evade the immune system, and an aggressive phenotype that promotes growth and metastasis. When a person is diagnosed with cancer, it is often discovered as the result of routine medical tests or when a person seeks treatment for a problem like persistent pain. The early diagnosis of cancer can improve outcomes. If the cancer is confined to the area in which it started, or if it has not spread, treatments can often stop the cancer from returning and help a patient live longer. Symptoms of cancer can range from very mild to severe and vary from person to person. Common symptoms include fatigue, weight loss, and pain that does not go away. Some people with cancer have blood in their urine or stool, and others may have abnormal skin changes, such as a mole that changes shape or color. Some types of cancer can be treated with surgery, radiation, or drugs. Many types of cancers can be prevented by avoiding tobacco, maintaining a healthy weight, and getting regular screening exams, including a physical exam and a history of previous health problems.