Neutering at 18-24 months should NOT increase their risk for testicular cancer or prostate issues. If it did, I would of had Blue castrated by now. They're first reaching maturity at this age. The prostate issues don't start until they're much older.
The point of waiting for us is not so he grows bigger, it's because testosterone does help in proper joint development which to me, is very important in bulldogs considering how they have hip issues.
In fact, ask your vet the following specific question (this is only for male bullies) and see how they answer.
1. How does neutering at 6 months of age improve my dogs health?
The truth is it doesn't. Again, social issues- yes, marking yes.. health wise, absolutely none. There is not one study out there, that shows neutering a male dog so young decreases any kind of cancer or has any other health benefit.
edited to add: I'm wondering where exactly in this thread did you get the "Waiting until 18-24 months ensures full maturation in males (masculinity, etc), but may increase their risk of cancers and shorter life."
No one said, or even implied anything of the sort.