I see that you're in California... is your father also a California resident?
If so, he should immediately apply for MediCal, especially if he has no or very little financial resources. He may also be eligible for county medical services in the city where he lives. Again, assuming that he lives in California... and, assuming that he has limited finances.
Other states may operate similarly... I'm only familiar with California. My brother is in a similar situation as your dad... no health insurance and the likelihood that he has Prostate Cancer. He's also unemployed.
It took some time and research... but, he now has city funded health insurance which is now covering all of his medical expenses including the services of a Urologist and an upcoming surgical procedure.
You might also consider a local medical clinic... often, they see people (even on a walk-in basis) at little or no cost to the patient. But, they are limited in what they can treat. And, they don't always have the kind of on-site specialists that patients need... They have, however, affiliations with other medical resources and they may be able to locate and arrange the kind of care that your father needs.
Take care... good luck... and my best wishes to your dad.
google ....clinical trials.... in a search engine and try to get in a free trial. there are many throughout the world, especially in the U.S.A. good luck!