HOUSTON-Physicians at Ben Taub General Hospital, Houston, noticed that an unusual number of patients were presenting with lymphoma as their first AIDS-defining event. This observation prompted a retrospective study of all HIV-positive patients with non-Hodgkin’s lymphoma presenting between 1989 and 2000.
HOUSTONPhysicians at Ben Taub General Hospital, Houston, noticed that an unusual number of patients were presenting with lymphoma as their first AIDS-defining event. This observation prompted a retrospective study of all HIV-positive patients with non-Hodgkin’s lymphoma presenting between 1989 and 2000.
Indeed, the analysis showed that 33 (35%) of the 88 patients identified in the study were newly diagnosed with HIV, whereas 55 were known to be HIV positive when their lymphoma was diagnosed, Suleiman Alfred Massarweh, MD, told ONI in an interview. In other cohorts of patients with HIV-related lymphoma, he noted, only 3% to 5% typically present with lymphoma as their first AIDS-defining illness.
This discrepancy may be explained, in part, by Ben Taub’s status as a community hospital. The hospital serves as the first destination for these patients at presentation, thus eliminating potential referral bias. "Most patients in the large cohorts already have their HIV diagnosis when they go to these referral centers," Dr. Massarweh said at the 43rd Annual Meeting of the American Society of Hematology (abstract 1434). He is a clinical fellow at Baylor College of Medicine.
The substantial number of newly diagnosed HIV patients with lymphoma in the Ben Taub database gave the Houston researchers a unique opportunity to compare these patients with lymphoma patients with known HIV infection.
Of the 55 known-HIV patients presenting with lymphoma in the study, 10 had no history of an AIDS-defining illness and were being followed by primary care physicians in the HIV clinic. The rest had a previous AIDS-defining event before their lymphoma presentation.
Dr. Massarweh noted that the new-HIV lymphoma patients tended to be a few years older than the known-HIV patients: an average of 41 vs 38 years.
A more important finding was that the new-HIV patients were significantly more likely to have Burkitt’s or Burkitt’s-like lymphoma. Conversely, the known-HIV patients, who typically were more immunocompromised, were more likely to have diffuse large B cell immunoblastic lymphoma.
In addition, gastrointestinal involvement was rare in the new-HIV patients, but was very strongly associated with known HIV. "Out of the 33 new-HIV patients, only one had GI involvement at diagnosis. The other 14 cases of GI involvement were in the known-HIV group," Dr. Massarweh said.
He noted that in most previous studies involving large cohorts, the investigators did not distinguish among different lymphoma types when determining trends in the incidence and outcome of AIDS-related lymphoma. "They put everything together," he said. "Central nervous system lymphoma should be out of the equation; it should be looked at separately because we know it occurs in very advanced patients with very low CD4 counts."
The Ben Taub cohort, he said, suggests that not all systemic lymphomas are the same either. "There is a variety that can develop in patients who do not have advanced immunosuppression, and this category may be amenable to treatments to reconstitute the immune system," he said. "These patients may be more likely to respond to their lymphoma therapy and have a chance of long survival."
The fact that patients with early HIV infection still develop lymphoma suggests, Dr. Massarweh said, that some pathogenetic pathway other than prolonged low CD4 counts may be responsible. "It might be due to other factors such as an endogenous cytokine imbalance," he said.