DURBAN, SOUTH AFRICA – The good news about non-Hodgkin lymphoma in the setting of HIV infection is that the risk drops dramatically after several years of antiretroviral therapy. The bad news? The risk still remains extraordinarily high, compared with the risk seen in the general population, Mathias Egger, MD, reported at the 21st International AIDS Conference.
That was a key finding in a new analysis of lymphoma trends in more than 210,000 HIV-positive adults on combination antiretroviral therapy (ART) during more than 1.1 million person-years of follow-up in North America, Europe, Latin America, and South Africa.
Bruce Jancin/Frontline Medical News
Dr. Mathias Egger
The non-Hodgkin lymphoma (NHL) incidence rate standardized to 40 years of age was 287 cases per 100,000 person-years. From a pre-ART baseline of about 500 cases per 100,000 person-years, it dropped “massively” within a year after going on ART. Even after 5 years of ART, however, the rate remained in the range of 60-200 cases per 100,000 person-years, depending upon geographic location and HIV transmission route. In contrast, the incidence rate among the general population of the U.S. and Canada, which is among the world’s highest, is less than 10 per 100,000 person-years, according to Dr. Egger, professor of epidemiology and public health at the University of Bern, Switzerland.
The risk of developing NHL in the setting of HIV infection varied by continent. It was slightly higher in HIV-infected patients in North America than in Europe or South Africa, although the South African data are considered unreliable due to underascertainment of cancers.
In Latin American HIV-infected adults the NHL rate was lowest of all, fully 54% lower than in Europe after adjustment for current CD4 cell count, ART regimen and duration, and transmission risk group. The low NHL rate in Latin America was driven by a very low risk in HIV-infected women.
Across the world, NHL rates in patients on ART were consistently lowest in women, intermediate in heterosexual men, and highest in men who have sex with men.
The explanation for the regional variation in NHL trends might plausibly involve differing prevalences of Epstein-Barr virus–2 and other oncogenic viruses as well as differences in the completeness of cancer ascertainment, Dr. Egger said.
While NHL is categorized as an AIDS-defining condition, Hodgkin lymphoma is not. Nonetheless, the risk of Hodgkin lymphoma is markedly increased in the setting of HIV infection. In one classic meta-analysis, it was increased by 11-fold, compared with that seen in the general population (Lancet. 2007 Jul 7;370(9581):59-67).
In a study of more than 41,000 HIV-infected European adults by Dr. Egger and his coworkers, the incidence of Hodgkin lymphoma was 49 cases per 100,000 person-years. Importantly, unlike in NHL, the cumulative incidence and mortality of Hodgkin lymphoma were unaffected by ART (Blood. 2011 Jun 9;117(23):6100-8).
The clinical implication of these trends in HIV-related lymphomas is clear: with more than 2 million new cases of HIV infection occurring annually worldwide, and with infected patients living far longer as ART transforms HIV infection into a chronic manageable condition, physicians can anticipate encountering a steadily growing number of patients with NHL and Hodgkin lymphoma, he said.
The NHL study was funded by the European Union and the U.S. National Institutes of Health. The analysis utilized data collected by the Collaboration of Observational HIV Epidemiology and Research Europe (COHERE) and the International Epidemiologic Databases to Evaluate AIDS (IeDEA). Dr. Egger reported having no financial conflicts of interest.