What is a tumor?

The word tumor is a broad term to identify any growth within the body but has become synonymous with a benign or malignant growth. At times the word neoplasm is used which is essentially a new growth of tissue that has no purpose or function in the body.

A tumor arises from uncontrolled or an abnormal growth of cells that has no physiological function in the body, occupies space or destroys surrounding tissue to fit in the specific area and can affect the function or health of the organ it affects.

Tumors should not be confused with other growth phenomenon in the body like hyperplasia or hypertrophy. These terms are used when an organ enlarges or when there is an increase in the organ’s cells or layers of tissue than would be considered the norm leading to an increase in size of the affected organ. This enlargement is not a tumor.

Types of Tumors

Simply, there are two types of tumors – benign or malignant. A benign tumor is not always thought of in the same serious light as malignant tumors. Benign growths usually have little or no clinical effect, however, depending on the location, a benign tumor can cause a number of signs or symptoms if it presses against important neighboring organs like a gland or nerve. A malignant tumor invades surrounding tissue while growing in size, destroying organs and tissue and may spread to other areas of the body.

Difference between a Benign and Malignant Tumor

Benign TumorMalignant Tumor
Mobile mass.Fixed or ulcerating mass.
Smooth and round with a surrounding fibrous capsule.Irregular shaped with no capsule.
Cells multiply slowly.Cells multiply rapidly.
Tumor grows by expanding and pushing away and against surrounding tissue.Tumor grows by invading and destroying surrounding tissue.
Mass is mobile. Not attached to surrounding tissue.Mass is fixed. Attached to surrounding tissue and deeply fixed in surrounding tissue.
Never spread to other sites (metastasize).Almost always spreads to other sites if not removed or destroyed.
Easier to remove and does not recur after excision.Difficult to remove and recurs after excision.

Differences between a benign and malignant tumor.
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Malignancy

Normal body cells are made up of organelles and a nucleus that contains the chromatin, which is a combination of DNA and proteins that make up a chromosome. This nucleus also contains a nucleolus, a small structure with RNA that plays an important part in protein synthesis. Under normal circumstances, cells of the same type are somewhat equal in size, have a common shape and spread out evenly. The cells grow slowly by a process known as mitosis, adhere (stick) to each other and spread out in a layer formation to collectively form a tissue.

Benign tumors also have normal cells and grow in an ordered manner. However a benign tumor has no physiological function and is therefore considered as an unnecessary growth in the body.

A malignant tumor does not have normal cells. These ‘cancer’ cells are different from normal cells in the following ways :

  • Irregular size of cell and nucleus.
  • Irregular shape of cell and nucleus.
  • Malignant cells stain differently from normal cells under microscopic examination.
  • Chromatin within nuclei clump irregularly.
  • Nuceloli are large, prominent and irregular.
  • Malignant cells do not stick (adhere) to each other as well as normal cells.
  • Malignant cells are compacted within a smaller area.

It is the abnormal genetic material in a malignant cell that is responsible for carcinogenesis (the process of malignancy). This genetic material causes the cells to behave, multiply and grow in the manner that is referred to as a malignancy.

What does cancer mean?

Cancer means that you have a malignant tumor. This tumor will grow over time and consume the surrounding tissue and will eventually metastasize. Once the tumor spreads (metastasis) it will consume the tissue at the new site and completely destroy the organ where it lodges. Death will occur once many organs are affected by cancer or if a vital organ, like the brain, liver or lungs, are extensively damaged. The only treatment for cancer is surgery (excision or removal of the tumor), radiation therapy or chemotherapy (drugs that are toxic to cancer cells). However once metastasis occurs, the prognosis is very poor and treatment at multiple sites is usually not viable.


Article reviewed by Dr. Greg. Last updated on December 11, 2009