Yes--I agree it should be reported.
Maybe tell his doctor about it if you don't want to do it yourself?
I do think the doctor would be obliged to report is an an offiical.
I'm so sorry.
My mother had this happen to her as well--lung cancer diagnosis on top of COPD
Because she refused to quit smoking or drinking or modify her lifestyle in any manner,
the doctors decided she was a poor prognosis for surgery and told me to contact Hospice,
and pretty much kicked her to the curb for treatment.
Hospice was amazing.
They helped me with counseling / visits and talked to her weekly directly about her life
and life decisions. They kept her physically as comfortable as possible, and not arguing
for pain meds constantly with a doctor was also helpful for both of us. I was done in by then.
I would also suggest you check with his town / county about *elder care services.
They can be official advocates for your brother if abuse is going on and will be a "front line" of defense legally to protect him and look after his rights.
*I'm assuming your brother is older from recalling the posts so apology if I'm incorrect.
Most important are Power of Attorney for Health and also financial if applicable.
Sometimes abusive children of elderly drain resources so again, the elder rights organization can become POA if you or other family members are unwilling / unable.