I don't spay/neuter my dogs and from Akitas/Black Russian Terriers/American Bulldogs/Shiba-Inus/Staffordshire Bull Terriers and Yorkies, I have yet to come across one at any age to have any sort of reproductive cancers or tumors. Except the one that was spayed. That was a female Akita and she came up w/ mammory tumors years AFTER she was spayed, a full ovarian hysterectomy.
I AGREE w/ spay/neuter, I really REALLY do. Just not for me. And I've never had an accidental pregnancy either.
IF you (the "royal you") decides to spay/neuter I also advise my clients on waiting until the dog is 16 + months of age, THEN have it done. I have an attached link that explains quite nicely.
http://www.caninesports.com/SpayNeuter.html
If you've already spayed/neutered your pet, this post is not implying you've done something wrong. Again, for me it's mostly about timing IF/when it's to be done.
Promote responsible ownership- that should be a vet's focus when it comes to this issue!