I think we need cancer and disease to control population
You think that this will fix the problem with the population?
Yes, and we need a good solution.
There's nothing wrong with having an unpopular belief here and there, but there's a difference when the belief is so offensive as wishing cancer on people. You shouldn't hope that anyone gets any sort of disease, even if you believe that it would solve a population issue.
I'm not wishing anything on people, I just think it's good for the cancerous population to die at some point since we need more room on the planet.
Population should not be controlled through diseases that cause suffering and death and your assumption that this idea is okay is wrong. There are other ways of controlling our population through freewill and choice.