19. present in fossil fuels; animal fats during process of broiling meats; smoked meat and fish
20.
21.
22. Any gene may be the target commonly mutated are RAS and p53
23.
24. Degree of risk depends on:Type of UV ray Intensity of exposure Quantity of light-absorbing protective coat of melanin
25.
26. UVB radiation is the main cause of sunburn and skin cancer although mounting evidence suggests UVA may also play a role. UVB does not penetrate the skin as deeply as UVA but has more energy and therefore does more damage to the skin.
27. UVB sunlight is directly absorbed by DNA resulting in single strand breaks and the formation of pyrimidinedimers.
79. Cancer cells entering the bloodstream form complex thromboemboli with platelets and leukocytes, which are thought to facilitate arrest at ectopic sites, assist interactions with the endothelium, and help in evasion of the immune system. Current data suggest that this phenomenon can be explained by interactions between platelet and/or endothelial P-selectin and carcinoma mucins.