Neutering actually increases the risk of prostate cancer (up to 4 times for some types, and up to 8 times for other types -- it's quite a signifigant increase in risk). There is alot of misinformation out there about prostate cancers.
But yes, unneutered dogs will be more prone to developing cysts and enlargement of the prostate -- most often in dogs over 9 years of age. Issues like this can usually be treated with medication, but neutering can also help or cure the problem. The last male I bred to was over 10 years of age. I liked the litter so much I tried to repeat it, but at over 10, he's now developed prostate issues, and the litter didn't take. His owners are going to put him on medication for his prostate. It can happen in younger dogs too, though much less common. a friend's male started having prostate issues at age 7. She put him on medication and it got rid of the problem. Another friend has a 6 year old male; Medication didn't help in his case, he neutered the dog, but the dog is still having prostate issues several months later. It seems to run in some lines.