Definition
What is a malignant tumor?
A malignant tumor is a tumor made of cancer cells. Unlike a benign growth, it does not respect tissue boundaries: its cells break through the basement membrane that normally holds them in place, grow into surrounding tissue and can enter blood and lymph vessels to set up new tumors in distant organs. Cancer and malignancy are other names for the same thing.
Malignant cells differ from normal ones in several ways. They keep dividing without growth signals, ignore signals to stop or to die, often look disorganized and immature under the microscope, and can coax new blood vessels to grow in and feed the tumor. Their chromosomes frequently carry many changes. The more abnormal the cells look, the higher the tumor's grade and, as a rule, the faster it grows and spreads.
Malignant tumors are named for their tissue of origin, for example carcinomas from epithelium and sarcomas from bone, cartilage, muscle or fat. Spread to distant organs, rather than the original lump, is responsible for most cancer deaths, which is why finding malignant tumors early matters so much.
Word parts
Where does the term “malignant tumor” come from?
- malign-
- bad by nature, harmfulLatin malignus, from malus (bad) + genus (kind)
- tumor
- a swellingLatin tumor
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Terms that go with it
- TumorA tumor is an abnormal mass of tissue made by cells that multiply too much or fail to die on time; it can be benign or malignant.
- Benign tumorA benign tumor is an abnormal growth of cells that stays in one place and does not invade nearby tissue or seed new growths elsewhere.
- MetastasisMetastasis is the spread of a cancer from its first site to distant organs, where escaped cells settle and grow into secondary tumors.
- CancerCancer is a group of diseases in which abnormal cells divide without control, invade nearby tissue and can spread to distant parts of the body.
- CarcinomaA carcinoma is a cancer that starts in epithelial cells, the cells that cover the skin and line the inner and outer surfaces of organs.
- OncogeneAn oncogene is a mutated or overactive form of a normal growth-promoting gene that pushes cells to divide uncontrollably and can cause cancer.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- NCI Dictionary of Cancer Terms: malignant
- National Cancer Institute: What Is Cancer?
- WHO Fact Sheet: Cancer
- Cancer Research UK: How cancer can spread
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