Image Caption : Cell Growth : In adults, cells normally grow and divide slowly and in a controlled way. This ensures that the number of cells in a tissue or system stays about the same. But in cancer, something goes wrong. One cell starts dividing out of control. In most types of cancer, a growing mass of cells called a tumor is formed.
Differences between Cancer Cells and Normal Cells
Cancer cells differ from normal cells in many ways that allow them to grow out of control and become invasive. One important difference is that cancer cells are less specialized than normal cells. That is, whereas normal cells mature into very distinct cell types with specific functions, cancer cells do not. This is one reason that, unlike normal cells, cancer cells continue to divide without stopping.
In addition, cancer cells are able to ignore signals that normally tell cells to stop dividing or that begin a process known as programmed cell death, or apoptosis, which the body uses to get rid of unneeded cells.
Cancer cells may be able to influence the normal cells, molecules, and blood vessels that surround and feed a tumor-an area known as the microenvironment. For instance, cancer cells can induce nearby normal cells to form blood vessels that supply tumors with oxygen and nutrients, which they need to grow. These blood vessels also remove waste products from tumors.
Cancer cells are also often able to evade the immune system, a network of organs, tissues, and specialized cells that protects the body from infections and other conditions. Although the immune system normally removes damaged or abnormal cells from the body, some cancer cells are able to "hide" from the immune system.
Tumors can also use the immune system to stay alive and grow. For example, with the help of certain immune system cells that normally prevent a runaway immune response, cancer cells can actually keep the immune system from killing cancer cells.
NIH: National Cancer Institute
Also called: Carcinoma, Malignancy, Neoplasms, Tumor
Cancer begins in your cells, which are the building blocks of your body. Normally, your body forms new cells as you need them, replacing old cells that die. Sometimes this process goes wrong. New cells grow even when you don't need them, and old cells don't die when they should. These extra cells can form a mass called a tumor. Tumors can be benign or malignant. Benign tumors aren't cancer while malignant ones are. Cells from malignant tumors can invade nearby tissues. They can also break away and spread to other parts of the body.
Cancer is not just one disease but many diseases. There are more than 100 different types of cancer. Most cancers are named for where they start. For example, lung cancer starts in the lung, and breast cancer starts in the breast. The spread of cancer from one part of the body to another is called metastasis. Symptoms and treatment depend on the cancer type and how advanced it is. Most treatment plans may include surgery, radiation and/or chemotherapy. Some may involve hormone therapy, biologic therapy, or stem cell transplantation.
NIH: National Cancer Institute
Cancer cells are cells that grow and divide at a rapid and unregulated pace. Although cancer cells are regularly created in the body, the disease known as cancer only occurs when immune cells (particularly natural killer cells) fail to recognize and/or destroy them. In the past a common belief was that cancer cells failed to be recognized and destroyed because of a weakness in the immune system. However more recent research has shown that the failure to recognize cancer cells is caused by the lack of particular co-stimulated molecules, such as CD80, that aid in the way antigens react with lymphocytes.
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