UPSC 2017 CDS I GK Paper

In a human body, the cell growth and differentiation are highly controlled and regulated, but in cancer cells, there is breakdown of these regulatory mechanisms, leading to the formation of benign and malignant tumours. Cancer starts when the cells in a part of the body start to grow out of control. Cancer cell growth is different from normal cell growth. Instead of dying, cancer cells continue to grow and form new, abnormal cells. Cancer cells can also grow into other tissues, something that normal cells cannot do.