You may donate if HIV positive to transplant centers that have HIV positive programs…ie you can donate to another hiv positive person, so it is possible, but not common at all.

Potential donors who have or had cancers, for instance, are almost always ruled out, since the drugs that suppress the immune system of the recipient so the organ isn’t rejected also stops the immune system from killing cancer cells. The immune system catches most cancer cells before they have the chance to find a location in the body to grow.