I prefer papers with a concrete conclusion and evidence in support of it,
When are studies ever really concrete? The majority of studies out there are based on manipulation and interpretation, which is why there are always conflicting studies. This is also why we have to weed through the studies to see how they were performed and interpreted.
But what the article was saying is that IGF-1 can cause cancer. And many studies back this up. But it is not going to cause cancer in everyone. They go on to say that there must therefore be contributing factors. We know that estrogen can cause cancer so why doesn't everyone on estrogen get cancer? Smoking causes cancer, so doesn't everyone who smokes get cancer? Again their are contributing factors like the article pointed out about IGF-1. So if we wrote an article about estrogen or smoking we could title them Does estrogen cause cancer? And does smoking cause cancer?