A review of the medical records of over 4000 HIV-positive Americans has revealed that cancers of the skin, anus and prostate gland and Hodgkin’s lymphoma are more common in people with HIV than in the general population. The study was published in the online version of the journal Cancer on 15th August.
In contrast to the AIDS-defining cancers Kaposi’s sarcoma, non-Hodgkin lymphoma and cervical cancer, non-AIDS-defining cancers do not lead to an AIDS diagnosis. However, a number of studies have found them to be more common in HIV-positive patients. Some studies have also linked them to the degree of immune damage. However, not all studies have agreed on the link between HIV infection and the incidence of non-AIDS-defining cancers.
In this study, investigators working on behalf of the United States government set out to assess the rates of non-AIDS-defining cancers in HIV patients being treated in military clinics. After comparing the rates of cancer diagnoses to those in the general population, they found that new cancer diagnoses were linked to being older, being HIV-positive for longer, being white and having had an opportunistic infection in the past.
In contrast, antiretroviral therapy reduced the overall incidence of non-AIDS-defining cancers.
“Based on the findings of the current study, we recommend considering the placement of cancer surveillance programmes within HIV clinics,” the investigators write. “Screening for skin malignancies as well as prostate and anal carcinomas among HIV-infected patients appears to be the highest priority”.
The investigators reviewed the records of 4144 HIV-positive patients attending one of the United States military clinics between 1988 and 2003, giving a total of almost 27,000 person-years of follow-up. Overall, 133 non-AIDS-defining cancers were diagnosed, with an overall rate of 980 diagnoses per 100,000 person-years.
The commonest cancers were skin cancers, affecting three different cell types. Basal cell cancers were the most common in 43 cases. These were followed by 16 squamous cell cancers and nine cases of melanoma.
After adjusting the results for age, the investigators found that squamous cell skin cancers were more common in the HIV-positive patients than in the general population (p = 0.001). Information on the incidence of cancers in the general United States population was gathered from the Surveillance, Epidemiology and End Results Program, a national registry of cancer information collected by the National Institutes of Health.
Anal cancer and Hodgkin’s disease were also more common in the HIV-positive patients (p < 0.05). In addition, Caucasian HIV-positive patients had a greater incidence of prostate cancer and melanoma than the general population, while African Americans showed a link between colorectal cancer and HIV disease (p < 0.05).
Using a multivariate analysis, the investigators calculated that a number of factors were linked to the incidence of non-AIDS-defining cancers. These were age over 40 years (odds ratio [OR] = 12.2, p < 0.001), being Caucasian and non-Hispanic (OR = 2.1; p < 0.001), being HIV-positive for longer (OR= 1.2; p < 0.001) and ever having had an opportunistic infection (OR = 2.5; p < 0.001).
Use of highly active antiretroviral therapy (HAART), defined as three or more antiretroviral drugs, was linked to lower rates of cancer (OR 0.21; p < 0.001). However, lowest-ever CD4 cell counts and CD4 cell counts at the time of diagnosis were not linked to cancer rates.
Due to small numbers of patients with each type of cancer, the investigators were unable to assess the risk factors for each type of cancer. Therefore, the lack of an association between overall non-AIDS-defining cancer rates and CD4 cell counts may not apply to individual cancer types.
However, the investigators presume that the increased incidence of cancer in white patients reflects the elevated risk of skin cancers in these patients. “Our finding that Caucasians / non-Hispanics had a two-fold greater risk of non-AIDS-defining cancers was noteworthy and likely is related to the high rate of skin cancers within our study cohort,” they write.