Outcomes from screening study for anal cancer in HIV positive compared to HIV negative patients

A recent paper in the September 2009 issue of Gut reported significantly poorer diagnostic results from colonoscopy screening in HIV positive compared to HIV negative controls.

This included higher prevalence of lesions, larger and more advanced lesions and that these were occuring at a younger age in the HIV positive group.

Bini and colleagues from New York performed coloscopy screening for colonic neoplasms in 136 asymtomatic HIV positive men older than 50 years and 272 HIV negative controls matched for age, sex and family history. All participants were patients at a single VA site, with screening performed from 2002-2004. Exclusion criteria included previous screening (5-10 years) or positive faecal occult blood test.

The median duration of infection in the HIV-positive groups was 11 years (IQR 7-14), median CD4 count was 346 cells/mm³ (IQR, 236-707) and around 90% were on HAART, 73% of who had had undetectable viral load.

The study found a significantly higher prevalence in HIV positive patients (62.5% vs 41.2% (p<0.001). This remained highly significant after adjustment for potential confounding variables, including age, sex, race/ethnicity, current alcohol use, current smoking, use of NSAIDs and aspirin, family history of colorectal cancer and history of screening.

Compared with control subjects, HIV positive patients had significantly increased odds of having a neoplastic lesion (OR = 2.38; 95% CI, 1.56 to 3.63). This association remained highly significant after adjustment baseline characteristics (OR = 3.00; 95% CI, 1.83 to 4.93) and after further adjustment for tobacco, alcohol, aspirin and NSAIDs (OR = 2.84; 95% CI, 1.74 to 4.62).

Compared with controls, HIV positive patients were significantly less likely to have hyperplastic (benign) polyps and were more likely to have adenomas 6-9 mm in diameter. More HIV positive subjects than control subjects had two or more adenomas detected (41.2% vs 30.9%, p = 0.04).

Among the 11 adenocarcinomas that were diagnosed, HIV positive patients were significantly younger than those without HIV (52.4 (SD 1.3) vs 60.3 (SD 4.0) years, p = 0.002), a difference of 7.9 (95% CI, 3.6 to 12.2) years. Late-stage adenocarcinoma of the colon (stage III or IV) was more common in HIV positive subjects (3/5 (60.0%)) than in controls (1/6 (16.7%)), although this difference was not statistically significant (p = 0.24).

The study found no association between neoplastic lesions of the colon and duration of HIV infection, CD4 count, or viral load, but a protective effect was reported in HIV positive people on HAART (OR = 0.13; 95% CI, 0.02 to 1.02).

The authors concluded that their findings suggest that screening colonoscopy should be offered to HIV positive patients, although the age of initiation and the optimal frequency of screening require further study.

These add to the growing evidence supporting a screening programme for HIV positive people as a targeted high risk group. See coverage in the EACS conference report earlier in this issue of HTB. [2]