In spite of several check points in a cell cycle to check any modifications in DNA before its transfer to next generation, certain mutations takes place in DNA leading to loss of certain characters and control over its multiplication rate.
The consequences of these modifications result in pathological over growth of modified tissues generally referred as Tumor or Neoplasia (meaning new formation) or “cancer”.
The altered character of tumor cells makes them immortal and they do not respond to the signals sent for regulation of growth. Even though rapid multiplication and uncontrolled growth are common characters for all tumors, certain tumors are less hazardous than the others.
The hazardous character of tumors depends upon the metastasis nature of tumors. Metastasis is the ability of cells to separate from the mass and move through lymph or blood to invade the surrounding tissue.
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The tumors with metastasis are referred as “Malignant tumors” and the tumors with out metastasis are referred as “Benign tumors”.