|Cancer is a malignant tumor which is a group of diseases that involve abnormal cell growth with the potential to invade or spread to other parts of the body. Not all tumors are cancerous. The benign tumors do not spread to other parts of the body and hence are not cancerous. The signs and symptoms include- a new lump, prolonged cough, abnormal bleeding, unexplained weight loss, and a change in bowel movements. These symptoms are not only of cancer, they may also be due to other infection so the occurrence of such symptoms should not be regarded as cancer. Cancer cells divide uncontrollably to form lumps or masses of tissue called tumors and harm the body. Tumors when grow, they interfere with the nervous, digestive and circulatory systems and release hormones that may alter body function. Tumors that remain at one point and have limited growth are benign or non-malignant.
Cancer is caused due to the cells that grow uncontrollably and are immortal. The healthy and normal cells of the body follow a systematic path of growth, division, and death. Every cell in the body has programmed cell death called apoptosis, and when this process is disturbed, cancer begins to form. This leads to formation of mass of abnormal cells that grows out of control. There is uncontrolled growth of cells only when there damage or mutation is caused to the DNA, and so the genes involved in cell division are damaged. Generally four types of gene are responsible for the normal cell division process- oncogenes that tell cells when to divide, tumor suppressor genes that tell cells when not to divide, suicide genes that control apoptosis and tell the cell to kill itself if something goes wrong, and DNA-repair genes gives instruction to the cell to repair damaged DNA.