Can anyone help me understand why we're even performing studies like this anymore? It would seem that all these years of "x can cause cancer" studies have just

Can anyone help me understand why we're even performing studies like this anymore? It would seem that all these years of "x can cause cancer" studies have just revealed that we generally know very little about what causes cancer. Is prevention really a viable avenue of control anymore? Shouldn't we just be focusing on early detection and treatment?