There eventually is enlargement of the lymph nodes, liver, and spleen. Common to all leukemias are the tendency to bleed and the resultant anemia and increased susceptibility to infection. The diagnosis of leukemia requires confirmation of leukemic cells in the bone marrow by bone marrow biopsy and aspiration.
River Phoenix's autopsy showed deadly levels of cocaine and morphine (heroin shows up as morphine, as it's metabolized by the body), Valium, marijuana and ephedrine. Ephedrine is the main ingredient found in crystal meth. Official cause of death was Acute multiple drug ingestion. River Phoenix was just 23 years old.
The Phoenix, still pretending to be Jean, died on the moon (arguably Jean's most famous death, but not actually Jean), and its conciousness was later added to Jean's, along with that of Madelyne Pryor, a clone of Jean who had also died.