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Cancer is the general term for malignant tumors, which is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. Compare with benign tumors, infectious tumors are named for malignant tumors. When a cell mutates in the body, it will continue to divide due to loss of control for proliferation, eventually forming cancer.
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Cancer Cancer is the general term for malignant tumors, which is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. Compare with benign tumors, infectious tumors are named for malignant tumors. When a cell mutates in the body, it will continue to divide due to loss of control for proliferation, eventually forming cancer. All organs in the body are composed of cells. Cell proliferation, differentiation and apoptotic pathways allow cells in the body to keep balance. However, if cells sustain to divide owing to loss of control, the extra cells will form tumors. In malignant tumors, it always shows the biological characteristics of abnormal cell differentiation and proliferation, loss of growth control, invasiveness and metastasis. These characters are necessary for cancer. In cancer, the biological characteristics also shows similar phenomena, such as: 1. Cell growth and division is out of control; 2. Cancer cell can avoid apoptosis; 3. Blood vessel construction is promoted; 4. Invasion of tissue and formation of metastases. Therefore, cells of malignant tumors can invade and destroy adjacent tissues and organs. Moreover, cancer cells can pass through the tumor and enter the blood or lymphatic system, which allows cancer to form new tumors from the original site to other parts of the body. This process is called cancer metastasis. Cancer is a multi-factor, multi-step complex process, and its causes are also very complicated. For example, smoking, infection, occupational exposure, environmental pollution, unreasonable diet, and genetic factors can cause cancer. According to previous studies, the result shows that tobacco use is the cause of about 22% of cancer deaths, another 10% are due to obesity, poor diet, and lack of physical activity or excessive drinking of alcohol. Other factors include certain infections, exposure to ionizing radiation and environmental pollutants. Approximately 5–10% of cancers are caused by inherited genetic defects from a person's parents. In addition, 15% of cancers are caused by infections in the developing world.
