However, some chemotherapeutic drugs are taken at home in pill form - this includes drugs like
dacarbazine,Nautal/Matulan (procarbazine), Cytoxan/Sendoxan (cyclophosphamide) and others, used for melanoma, lymphomas as well as other type of cancer.
So in short, there's no reason to worry about the HIV test being affected. But if the person is indeed undergoing chemotherapy, avoid sexual contact or at least use a condom, 48 hours after administration.