That’s not cancer, but cutaneous fibromas. Does not affect the meat. Look here - http://home.mdwfp.com/wildlife/species/deer/articles.aspx?article=115
According to Mississippi Game Department, these are ‘fibromas’ that are commonly called deer warts by hunters. See excerpts below.
‘Fibromas are caused by a virus which is thought to be transmitted by various biting insects. However, another possible means of transmission of the viral agent is direct contact through any assortment of contaminated objects which may scratch or penetrate the skin of the deer…
...Rarely do fibromas cause deer any problems, but occasionally the location of a large single or multiple clump of fibromas can interfere with sight, eating, breathing, or even affect the ability of the deer to walk. Occasionally, the larger fibromas acquire a bacterial infection through a break in the skin…
...No human infection from cutaneous fibromas has been reported. The only concern for hunters would be from an animal with extensive bacterial infection, which would render the deer unsuitable for human consumption. These animals would be readily apparent due to the unpleasant exudate produced at the infection site…
...In summary, cutaneous fibromas are merely skin blemishes of white-tailed deer. They are of no significance to the health of the deer population. ’