Fun fact: protein and fats are essential to your diet. Carbohydrates are optional. In any case, I'm a runner and it is just one of my sources of protein, typically after exercise.

Interactions with Cancer Metabolism:

https://examine.com/supplements/whey-protein/#summary10

Comparison to Other Protein Sources:

https://examine.com/supplements/whey-protein/#summary15

Even if whey protein grew cancer (which is a pretty dubious claim), you could say the same thing about the sun.

"Stop going outside. The sun literally grows cancer. Are you a baby cow?"

Do you have a source for this insane claim?