My husband went through prostate cancer over two years ago. Perhaps I can help with something.
It sounds like your father may have had prostate cancer. Not sure of his treatment. But he may be watching his PSA numbers. If they rise, cancer may be reoccurring. I would really need additional information to suggest anything more.
Frequent bathroom trips at his age could be BPH, diabetes, medication, etc. I don't think this must mean the cancer is progressing. His elderly age brings many other problem to the forefront, especially with elimination, eating, circulatory, etc.
I'd say whatever your dad is doing, I would do the same.
He actually sounds pretty healthy for 95.