I don't know if it causes those cancers, but the risk increases. My uneducated theory is that we all have cancer cells, and the hormones and function of those glands can keep all things in a balance, and thus more healthy. When they are removed, especially early before maturation takes place, the lack of them causes other things to be a bit out of whack and for some dogs the cancer cells then are not kept in check and the develop cancer sooner.
As for testicular cancer it is rare, and relative easy to diagnose and generally can be treated by neutering at that point. With a retained testicle, abnormalities will be harder to notice and therefore the risk becomes greater, for the retained testicle. Testicular cancer generally hits older dogs.
The other cancers whose risk is increased by early neuter, take them younger and are tougher to manage, these are osteosarcoma, hemangiosarcoma, and prostate cancer.
Wandering is a containment issue. A wondering dog can get themselves in a world of pain whether neutered or not. I think the reason a lot of intact dogs are picked up wandering is while not everyone that doesn't alter their pet is irresponsible, but most irresponsible people do not bother to neuter, and dogs that are wandering, their owners are irresponsible. So, most wandering dogs will be intact.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC