This was one experiment by a guy who was criminally convicted for his illegal methodology for the same experiment. His experiments never reached the conclusion you are claiming, generally because his victims were cancer patients who already had cancer.

Half a century of medical research following this experiment suggests that cancer is not contagious in any real way. Comparing this to HIV is wild when in your OP you claim that transmissible cancer is somehow airborne. Apparently you think that people are just breathing out lung cells or something…

Your whole tone here is coming across as “14 year old who just read about a medical atrocity and thinks it would be edgy to evangelize human butchery as respectable medical science”. Southam was a quack, and treating his experiments as scientifically sound is a form of malice.