Patients with AIDS and PCNSL have a median survival of only 4 months with radiotherapy alone. Untreated, median survival is only months, sometimes due to concurrent opportunistic infections rather than the lymphoma itself. Extended survival has been seen, however, in a subgroup of AIDS patients with CD4 counts of more than 200 and no concurrent opportunistic infections, who can tolerate aggressive therapy consisting of either methotrexate monotherapy or vincristine , procarbazine, or whole brain radiotherapy. These patients have a median survival of 10–18 months. Of course, highly active antiretroviral therapy (HAART) is critical for prolonged survival in any AIDS patient, so compliance with HAART may play a role in survival in patients with concurrent AIDS and PCNSL. 
One of the main side effects is risk of infection . Chemotherapy temporarily reduces the number of white blood cells, which help fight infection. You may be given drugs to reduce your risk of getting an infection. Chemotherapy can also affect red blood cells, which carry oxygen around the body, and platelets which help the blood to clot. Other side effects can include feeling sick , sore mouth and hair loss . There are different ways side effects can be controlled or managed. Always let your doctor or nurse know about any side effects you have. We have more detailed information on side effects of chemotherapy .