Inoperable prostate cancer for 5 yrs: Low energy and worried

@trazzy We did not know before we saw a neurologist that problems with gait and balance while walking can be a symptom of mild cognitive impairment (for my wife's father.) He was 78. Physical therapy helped, but the physical therapist we saw stopped treatment because he was not continuing to progress. In his case, the therapy was helping to prevent further decline which that therapist did not think met insurance guidelines. I would get another therapist now in that situation.
I mention this because the other symptoms may also be neurological. Foggy, forgetful, and "not hearing" is a frequently used proxy for not processing the same as before. The brain scan recommendation goes with this line of thought as does the geriatrician. In our context we do not have many geriatricians, and neurologists are usually the ones dealing with these concerns, so that may be an alternative referral possibility.
Of course, it could also be spread of the cancer although the oncologist is apparently ruling that out at this time.
Regardless, our hearts go out to you both with this multifaceted set of challenges.

trazzy, it's so good that you are taking close care. The MRI is a good measure it won't measure TIA, unless it recent, but brain bleeds tumors and structural abnormalities
Never hurts to see a geriatrician.
I would want a second from an oncologist. There have been many changes in prostate cancer care in the last five years with checkpoint inhibitors and a new contrast agents for detecting spread. Our brains are often a destination for metasatic cancers. I pray not and it is good that the oncologist thinks not, but it is something that you'd need to know.
On the other hand, sometimes the elderly are too quickly slotted into a dementia diagnosis. Depression is a cause of fatigue. And fatigue on its own can cause lack of concentration which causes loss of balance and seeming hearing loss.
Low testosterone usually causes some fatigue and depression. I can't think that low dose testosterone gel would be restorative.
From my experience aftercare for cancer isn't great, especially after the five year mark.
You might take him for a hearing test. It is easiest at the hearing aid retailers, though you could see an otolargyngologist. I would want to test testoserone levels, if they haven't been tested.
We drive ourselves crazy speculating. I would schedule both doctors at right away, so you aren't waiting so long. You probably don't need a referral for either.
I'm praying that it's low B12.
Best wishes

Just a note: I'm 15 years younger, but my balance and gait problems came because my (then-undiagnosed) prostate cancer had metastasised to my spine and the lesion was compressing my spinal cord. So make sure that they check for that, and don't just assume that it's because of aging.

As mentioned above, the balance problem could be a low B12 level. Our B12 absorption becomes less as we age. Several years ago I had to walk with a cane just to keep my balance. At home if standing, I would lean against the wall or the kitchen counter. My B12 level was 85. Added to that I was later diagnosed with low testosterone (186). The two together made life horrible. Monthly B12 injections and daily Androgel have me back a normal life. Low B12 can also affect the nerves in the ears which could affect hearing. Might be worth checking, it's just a routine blood exam.

Thank you so much for sharing your experience it points out some very interesting facts. Especially regarding physical therapy. He is extremely disciplined with daily exercise and even when exhausted he still exercise’s. He and I know how important it is especially with cancer.

Thank you, here in Australia our medical system is different and you can’t see a specialist doctor without an appointment from your GP. Lucky we have an great GP who has organised an appointment with a geriatrician because then all test, scans etc will be managed in one place.
Last test his testosterone level has shown an increase and he will have that checked again in a month. B12 is definitely something I will check into as well. Thanks again

Oh so sorry to hear but very interesting regarding your spine. Many years ago he had 2 laminectomy’s so I will definitely look into this
Thanks again

Thank you, will definitely look into the B12 and the gel he has been prescribed is Testogel not sure if that is similar to Androgel. He has been using this for about 3 months and has had a slight increase in testosterone. But certainly not energy.

This morning there was a relevant link shared under a new topic "Cognitive Impairment Amongst Prostate Cancer patients." by @gkm The article was not so much new research, but rather highlighting that cognitive impairment can be a side effect of treatments for prostate cancer. The article also highlighted that this is an aspect of care that is receiving little attention. Here is the link https://link.springer.com/article/10.1007/s12325-023-02721-9

Thank you very much the article is extremely interesting