What Does 20 Chance Of Getting Cancer Mean?

I assume you mean a twenty per cent chance of getting cancer. A number mentioned in terms of percent automatically means that it is a unit out of hundred units. In simple words, fifty percent of something pertains to fifty out of hundred, meaning half. In the same way, twenty percent refers to twenty out of hundred. A percentage is just a simple way of describing a quantity, as it is always compared to a hundred units of the quantity. This is equal to 0.2 units. So when you say a twenty percent chance of cancer it simply means that you have a 0.2 percent chance of getting cancer. This means you only have a slight risk of contracting the disease as opposed to sixty per cent which means a 0.2 risk factor.