There is normally a pair of each human chromosome. In cancer, there may be alterations in chromosomes, including gain or loss of copy number, deletion of genetic material, or joining together of unrelated chromosomes. I.Smoking - tobacco smoke is the most lethal carcinogen in the US Smoking is associated with cancers of the lungs, esophagus, bladder and pancreas.
Risk is dependent on frequency of smoking, tar content, and age at which smoking began.
Second hand smoke also puts people at higher risk. Most serious danger is overexposure to the UV B rays of the sun which can cause melanoma skin cancer. B. Radon gas Emitted from soil in some areas and may collect in well-insulated basements. Also occurs in mines. Place Compounds such as asbestos, benzene, formaldehyde and pesticides.