First, you have to accept the fact that in medical terms there are no guarantees. You can predict a risk factor, there is no 100% certainty. Consider this: Smoking increases your risk for lung cancer by 30%. And yet, many people smoke all their lives and live long and healthy without any cancer. Thousand of studies do show that vegans have a 35% lower risk for cancer. But it is not guaranteed. Ironically, so many people quit smoking because of the association with cancer, yet, many people refuse to give up meat to reduce their risk for cancer.
Also, being a vegan, or vegetarian does not mean you are eating healthy! Vegans may still conjsume plenty of fats, sugars and processed food-like items that have about as much nutrients then the box they came in. You can only reach optimum health if you consume the most nutrient-rich raw foods on this planet, and they include: fruits, vegetables, legumes, beans, nuts and seeds. You may Google and research some miracle-like cases where people reversed their cancer, heart disease, diabetes and many other illnesses by going on a radical plant based diet. Bill Clinton is a popular example, but there are many more.
So, when someone tells me that vegans still get cancer, I reply with just that.
Here is to good health and compassion!