I read a study in a doctors magazine about 3 weeks ago that they did a preliminary study of this with 17 people! They move quick when there's a chance to prove Cannabis is evil don't they!?
Maybe if they did the same for all of it's benefits and published those then weed wouldn't have such a bad name.
Honestly, they shouldn't publish ANY pre-clinical trials. They can be COMPLETELY wrong and it just misleads the public because they won't follow up on it later on (the people or the media) and majority of people know fuck all about the scientific method and will just take the headline as gospel.

"and all were residents of the Seattle-Puget Sound region."
So maybe there was an environmental factor? Maybe there's some sort of pollution right next to their house? A number of other things are possible, that's why real studies look at a wide group of people and also don't just ask them how much they smoke.
"The men reported any history of marijuana use, as well as alcohol and smoking habits, and the same information was collected from about 1,000 healthy men."
Now I don't know where the actual study is, but why did the reporter not mention the use of alcohol and tobacco? Hmmmm.... tough one there, she/he has gots the reefer madness!
I'm pretty sure all the studies about Cannabis and lowering sperm count/quality has been shown to be bullshit. I'm pretty sure smoking tobacco and drinking alcohol lowers your sperm count too. (both which are PROVEN to cause cancer beyond a doubt)
But that's kinda beside the point because how does lower sperm count correlate with an aggressive form of cancer?
Who the fuck knows!