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Oral Cancer Rate Higher With HIV--Lower CD4s Implicated in People Over 49
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19th Conference on Retroviruses and Opportunistic Infections, March 5-8, 2012, Seattle
Mark Mascolini
Overall oral cavity and pharynx cancer incidence (the new diagnosis rate) in North American patients with HIV is 60% higher than in the general population, according to a large NA-ACCORD analysis [1]. Among HIV-positive people 50 or older, oral cancer incidence is almost twice higher in those with an initial CD4 count below 350 than in those with a higher initial count.
Oral cavity and pharynx cancers are relatively rare in North America, though some evidence suggests HIV-positive people run a higher risk, for two reasons, according to NA-ACCORD investigators. First, about 75% of cases result from smoking or drinking alcohol, and people with HIV smoke more than the general population. Second, human papillomavirus (HPV) has been implicated in a subset of oral cavity and pharynx cancers, and both HPV and HIV are sexually transmitted infections.
This analysis involved 51,151 HIV-positive people in 14 cohorts across North America. The researchers tracked down cases of oral cavity and pharynx cancer and validated them through chart review with clinical confirmation or cancer registry linkage. They calculated prevalence and incidence stratified by smoking history (ever versus never), age, calendar time, and first recorded CD4 count (below 350 versus higher). The investigators compared rates in these HIV groups with the Surveillance Epidemiology and End Results (SEER) population restricted to people 20 or older.
The NA-ACCORD team found 7 prevalent (existing) cases of oral cavity and pharynx cancer for a prevalence of 14 cases per 100,000 people. Forty-three oral cavity and pharynx cancers got diagnosed during follow-up to yield an incidence of 16.4 cases per 100,000 people (95% confidence interval [CI] 12.1 to 22.1). The age-standardized incidence rate came to 21.7 cases per 100,000 people (95% CI 92. To 34.3).
Among the 43 people with incident (newly diagnosed) oral cavity and pharynx cancer, median age stood at 44, compared with 38 in the entire cohort. Median initial CD4 count was 324 in the cancer group and 333 in the entire cohort. People diagnosed with oral cavity and pharynx cancer had a lower baseline viral load than the entire cohort: 5382 versus 13,068 copies. Everyone who got cancer smoked. Only one quarter of the cancer group and one quarter of the entire cohort were taking combination antiretroviral therapy when follow-up began.
Compared with the SEER database, oral cavity and pharynx cancer incidence was similar in the HIV group before 1996, from 1996 through 2000, and from 2001 through 2005. But from 2006 through 2010, oral cavity and pharynx cancer incidence was 30.1 per 100,000 in the HIV group and 14.9 per 100,000 in SEER, a significant difference (P = 0.03).
Overall incidence was 21.7 per 100,000 in the HIV group and 16.7 per 100,000 in SEER. The oral cavity and pharynx cancer standardized incidence ratio was 1.6 (95% CI 1.1 to 2.1), meaning people with HIV had a 60% higher incidence than the general population.
Among people with HIV, oral cavity and pharynx cancer incidence varied greatly by age, but it varied by CD4 count only in people 50 or older. For people under 40 years old, incidence was 0 with a baseline CD4 count below 350 and 5.6 per 100,000 with a higher CD4 count (versus 1.7 per 100,000 in SEER). Respective incidence rates in 40-to-49-year-olds were 20.3 and 22.8 per 100,000 (versus 9.5 in SEER).
But among HIV-positive people 50 and older, incidence was almost twice higher in those with a baseline CD4 count below 350 than in those with a higher baseline CD4 count: 45.7 versus 24.3 per 100,000, though that difference fell short of statistical significance (P = 0.08). Oral cavity and pharynx cancer incidence in SEER for the 50-and-older group is midway between these rates--36.6 per 100,000.
The NA-ACCORD investigators called the incidence of oral cavity and pharynx cancer "modestly higher" in HIV-positive people than in the general population. The higher incidence among people 50 and older with a baseline CD4 count under 350 versus over 350 suggests poor immune status may contribute to the risk of these cancers in older HIV-positive people. The investigators cautioned that they have smoking histories for only about half of the cohort, and they have not yet collected data on sexual behavior and alcohol use, which could affect risk of oral cavity and pharynx cancers.
Reference
1. Abraham A, Jing Y, Beachler D, et al. Incidence and risk factors for oral cancer among HIV+ individuals: North America. 19th Conference on Retroviruses and Opportunistic Infections. March 5-8, 2012. Seattle. Abstract 133.
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