HFsbertram, - More information is needed to intelligently reply regarding your Father's specific case, but these realistic "in general" considerations may be sufficient to remove some of the present confusion in your mind
First, there are no absolutely right or wrong answers to your fathers dilemma, since recognized experts disagree on the best way to treat Prostate Cancer (PCa) at various stages of the disease.
Second, your Father's age, is a major consideration when weighing viable treatment options, since the average life expectancy for an 80 year old male, according to Social Security Life Actuarial Tables, is 7.9 years.
Third, statistically, most men diagnosed at the age of 80 are more likely to die of something other than PCa, since it is often, but not always, a slower growing tumor than many other competing threats to survival at more advanced ages.
Fourth, co-morbidity (other diseases and symptoms that may simultaneously exist) are to be considered when weighing advantages and disadvantages of varying treatment options.
Fifth, one of the most important considerations is the clinical Gleason SCORE which helps to determine the likely aggressiveness of the current disease. The effectiveness of specific treatments in "curing" or "controlling" the present disease is highly dependent on whether the STAGE of present disease is thought to be "localized", "locally extended, which is sometimes called regional" or whether it is already "systemic" and is circulating in the blood system.
Unfortunately, some of these factors cannot usually be determined with certainty and the statistical likelihoods (the odds) must be used to predict most likely probabilities.
Sixth, you are already, there is a great deal of misinformation in the public sources (like the Internet), as well as its ability to provide many very good resources. The problem is that the newly diagnosed have little background or scientific knowledge to judge which is reliably accurate and which is NOT.
The fact is that the the strength of the photon rays and the proton rays used in the two forms of Radiation Therapy (RT) are determined, planned and controlled by the those professionals rendering the treatment. At the same level of measurement arriving at the targeted area, the rays themselves, are equally strong and effective at that point of delivery. There are other differences in delivery but NOT in the presently PROVEN or KNOWN effectiveness in Cancer Control.
I am NOT a physician but If you will E-mail me, I will furnish you with my medical background and my telephone number in Scottsdale, AZ if you wish. - John@newPCa.org (aka) az4peaks