Anal cancer occurs more frequently in HIV-positive gay men, doesn’t respond to HAART, is difficult to treat, has a poor outcome, but is, thankfully, rare, according to data from the largest UK HIV cohort presented to a forum on HIV and cancer on January 17th organised by London University's Wolfson Institute.
Since 1986, 8,640 individuals have been enrolled into the Chelsea and Westminster HIV cohort, providing over 40,000 patient years of follow-up. A total of 26 cases of invasive anal cancer have been diagnosed during this period, 25 of them in gay men (the remaining case being in a heterosexual woman).
Although a pre-HIV US study showed that gay men were 33 times more likely to develop anal cancer, data from the Chelsea and Westminster cohort showed that the incidence of anal cancer was even higher in HIV-positive individuals, at 60 cases per 105 patient years of follow-up, against 0.5 cases per 105 patient years in the age and sex matched Thames Cancer registry. This finding was consistent with a US study which found that gay HIV-positive men had a risk ratio of developing anal cancer of 66.
Unlike the AIDS-defining cancers Kaposi’s sarcoma and non-Hodgkin’s lymphoma, the development of anal cancer was not linked to severe immune suppression, the median CD4 cell count of individuals presenting with anal cancer being 206 cells/mm3.
The incidence of anal cancer has not fallen with the introduction of HAART (p>0.05). Since 1996, 67% of individuals diagnosed with malignancy have been taking HIV therapy, and 28% (18 individuals) have had a viral load below 50 copies/mL.
Clinicians at the Chelsea and Westminster used chemoradiotherapy to treat anal cancer in 22 individuals, surgery in two patients with small cancerous lesions, with the remaining two patients, who had advanced HIV disease, receiving palliative care only. A total of eleven patients died, seven of anal cancer and four of an AIDS-defining condition.
This provided a two-year survival rate of 47%. Further, the prognosis of patients with anal cancer in the Chelsea and Westminster cohort has not improved since the use of HAART. Neither CD4 cell count, use of HAART, history of a prior AIDS-defining illness, nor length of HIV diagnosis of prognostic value.
To further enhance these data, the London investigators pooled their findings with those of US clinicians. This provided the investigators with information on a total of 46 individuals. The findings were consistent with those from the 26 London patients. A third of individuals died of anal cancer within a year of diagnosis and the 66% one-year survival rate continued to decline with time.
The bad news didn’t end there. Screening for anal cancer appears to be of no particular value.
A pilot programme to detect cancers and precancerous cells in the anus - anal intraepithelial neoplasma (AIN) – was conducted at the Chelsea and Westminster Hospital. A total of 156 screens were conducted on 100 patients. All individuals with AIN were infected with the HPV virus, which causes genital and anal warts. Certain strains of HPV, particularly HPV-16, have been associated with an increased risk of cancer. However, the London investigators found that no particular strain of HPV was associated with the presence of AIN, suggesting that infection with any strain of HPV increased the risk of precancerous cells developing.
Furthermore, no correlation was found between the presence of AIN and either CD4 and CD8 cell count, or HIV viral load.
To see if HAART had an impact on the AIN, 23 gay men were assessed six months after starting HIV therapy. The grade of AIN went down in 35% of individuals, remained stable in 43%, and become worse in 22%. Changes in CD4, CD8, or viral load after starting HAART were not related to alterations in the grade of AIN.
Difficulties in the management of AIN were also encountered by the Chelsea and Westminster clinicians. The use of surgery to remove the precancerous lesions left 50% of individuals in uncontrollable pain for over three weeks, and 75% experienced a recurrence of AIN within three years.
Further information on this website
Anal cancer risk high in all HIV-positive men regardless of sexual behaviour - news story
Genital warts - factsheet
Bower M. HIV associated anal cancer and anal intraepithelial neoplasma. Oral presentation, AIDS-related cancer forum, Wolfson Institute for Biomedical Research, University College London, January 17th, 2004.