Pedro Alcazar

I was reading this boxing magazine recently, and there was an article talking about deaths in boxing. One of the fighters pictured was Pedro Alcazar who died in a TKO loss in the 6th round (I think that was the 6th round). They said that the cause was due to a previously undiagnosed brain injury. This concerned me, especially when I saw his record and saw that he had no previous losses. It made me wonder, did the guy take some pretty big shots in previous fights and not get checked up afterwards or did the doctors simply not notice it? The magazine said that his brain was bleeding before the fight, and that just seems like something that if a doctor looked at would be noticable. It got me thinking again about the woman who died in the amatuers just recently. Originally, I didn't give it much thought. But that's the first time I've ever heard of anyone dying in the amateurs. Did she take alot of heavy blows or was it just a shot thing?