MRI's are not a big deal, and should be considered. But I would think hard before doing a Biopsy, as there are significant risks, especially for an 85 year old. I knew gentleman in his 80s who died of sepsis the day after a biopsy. (And the biopsy was negative).
If there is cancer, treatment is only worthwhile if the cancer would reduce your father-in-laws life expectancy. Life expectancy of an 85 year old male is 6 years, and most cancers would not reduce this. If there will be no treatment, irrespective of the result of a biopsy, then there is no point in a biopsy.
I would certainly veer away from any treatment which does not increase life expectancy. Then there is the question of quality of life. There are degrees of dementia. If I was 85 and suffering severe dementia, then I would not do any treatment that increased my life expectancy.
Best of luck with everything.
Edited by member 10 Feb 2020 at 18:11
| Reason: Not specified