Testicle cancer

I had a miscarriage a few months ago. My partner has just been diagnosed with testicular cancer. I don't want to say anything to him but I can't help but think what if the "sick" testicle made a "sick" sperm that created a "sick" foetus that didn't survive past 10 weeks. I mentioned this to my best friend and she said "I don't think it works like that." Well then how does it work? Can anyone shed any light?