This is the NHS advice re existing medical conditions and being a donor
Can I become an organ donor if I have existing medical conditions?
Having an illness or medical condition doesn't necessarily prevent a person from becoming an organ or tissue donor. The decision about whether some or all organs or tissue are suitable for transplant is made by a medical specialist at the time of donation, taking into account your medical, travel and social history.
There are very few conditions where organ donation is ruled out completely.
A person cannot become an organ donor if they have or are suspected of having:
Creutzfeldt-Jakob Disease (CJD)
Ebola virus disease
Active cancer*
HIV
* Someone with current active cancer cannot become an organ donor. However, it may be possible for people with certain types of cancers to donate after three years of treatment. It may also be possible to donate eyes and some tissue in these circumstances.
** In rare cases, the organs of donors with HIV have been used to help others with the same conditions.
The decision about whether some or all organs or tissue are suitable for transplant is always made by a medical specialist at the time of donation, taking into account your medical history