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NCI sees "sizeable absolute risk" of cancer in elderly with HIV
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CROI 2015, February 23-26, 2015, Seattle, Washington
Mark Mascolini
HIV-positive people 65 and older in the United States have a "sizeable absolute risk" of cancer--including several non-AIDS cancers--according to a large case-cohort analysis by Elizabeth Yanik and National Cancer Institute (NCI) colleagues [1]. Among non-AIDS cancers, elderly people with HIV had more than a 30 times higher relative risk of anal cancer than people without HIV.
Previous research links HIV to a higher risk of several cancers, the NCI team noted, but whether the size of this inflated risk remains as high in older age is poorly understood. Elderly people in the general population certainly run a higher risk of many cancers, and HIV populations are now living long enough to permit cancer-risk comparisons with older HIV-negative controls. To address these issues, Yanik and colleagues planned this analysis with two aims: (1) evaluate the relationship between HIV and cancer incidence in people 65 and older, (2) estimate absolute risk of cancer in HIV-positive people 65 and older.
The NCI team created their study group by using the Surveillance, Epidemiology, and End Results (SEER) database linked to Medicare rolls. (US citizens must start using Medicare at age 65.) The investigators identified HIV-positive people through Medicare files and identified cancer diagnoses through SEER. The analysis excluded basal and squamous cell skin cancers. The researchers used weighted Cox regression to estimate hazard ratios comparing cancer incidence with and without HIV. Multivariable regression analysis adjusted for age, race, sex, and calendar year. The NCI team estimated cumulative cancer incidence after accounting for competing risks of death.
The analysis included 469,954 people, 361 (0.08%) of them with HIV infection. During the 2002-2009 study period, 42,485 cancers were diagnosed in this 469,954-person cohort. Among people with HIV, the most frequent cancers were lung cancer and prostate cancer (111 each), followed by non-Hodgkin lymphoma (57), colorectal cancer (40), anal cancer (27), and liver cancer (22).
Cumulative 5-year cancer incidence in people with HIV approached 12% in men and reached 6% in women. Compared with HIV-negative people, the HIV group ran significantly higher risks of Kaposi sarcoma, anal cancer, Hodgkin lymphoma, non-Hodgkin lymphoma, liver cancer, and lung cancer, as indicated by the following adjusted hazard ratios (aHR) (and 95% confidence intervals [CI]):
-- Kaposi sarcoma: aHR 79.2 (42.9 to 146)
-- Anal cancer: aHR 32.4 (21.6 to 48.5)
-- Hodgkin lymphoma: aHR 9.96 (4.89 to 20.3)
-- Liver cancer: aHR 3.83 (2.46 to 5.97)
-- Non-Hodgkin lymphoma: aHR 3.01 (2.24 to 4.05)
-- Lung cancer: aHR 1.52 (1.21 to 1.91)
Of these cancers, Kaposi sarcoma and non-Hodgkin lymphoma are the only AIDS cancers. Risk of non-Hodgkin lymphoma with HIV varied greatly by type: Risk with HIV was highest for Burkitt lymphoma (aHR 21.8, 95% CI 6.91 to 68.5) and diffuse large B-cell lymphoma (aHR 5.56, 95% CI 3.69 to 8.39) but lower for other types. Among non-Hodgkin lymphomas diagnosed in people with HIV, almost half were diffuse large B-cell lymphoma.
The NCI team noted that their analysis is limited by the unknown duration of HIV infection in these people and by lack of information on cancer risk factors like HPV infection and tobacco or alcohol use. With those limitations in mind, they concluded that, "reflecting the effects of both HIV and aging, the absolute risk of cancer was sizeable in HIV-infected men and women." That finding underlines the need for better cancer prevention and screening in people with HIV.
Yanik and colleagues noted that HIV in this elderly study group "is associated with higher risk for many cancers identified as HIV-associated in younger populations." They observed that the relative risk elevation of non-Hodgkin lymphoma was lower than in younger people, a finding that reflects "higher frequency of non-Hodgkin lymphoma subtypes less strongly associated with HIV."
Reference
1. Yanik EL, Katki HA, Engels EA, et al. High cancer risk among the HIV-infected elderly in the United States. CROI 2015. February 23-26, 2015. Seattle, Washington. Abstract 725.
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