The human body is made of a large number of minerals, and one of the most commonly present is calcium. Most of this mineral is in bones where it has the function of maintaining the density and strength. Calcium cannot be produced in the body so we have to take it with food. Vitamin D is particularly important for its absorption. Ca 2+ was not found throughout the cell and the flow cytometry technology offers many advantages over traditional techniques for measuring intracellular Ca 2+ level. The disorder of normal Ca 2+ signal contributes to the development of malignant phenotypes. Physiologically, calcium can be divided into either intracellular or extracellular. Calcium-binding intracellular protein, calmodulin, is an intermediary molecule in many calcium activities because it allows its movement from one part of the cell to another. Intracellular Ca 2+ homeostasis changes in the cancer cell and change is also involved in tumor initiation. Cancer cells use the same calcium channels and pumps as non-malignant cells. Transition of Ca 2+ through the plasma membrane is a key trigger or cellular processes in tumor progression.Tumor represents a set of changed cells that show an irregular and progressive tissue growth. The process of transforming normal cells into tumor cells is called a neoplastic transformation. A malignant tumor that can be life-threatening is called cancer.