HIV-related Anal Cancer: Has HAART Reduced the Incidence or Improved the Outcome?  
 
HAART reduced the incidence and improved the survival of patients with Kaposi sarcoma and AIDS-related non-Hodgkin lymphoma. This study evaluates its effects on incidence and survival in HIV-associated anal cancer.

The investigators measured the incidence and survival of patients with invasive anal cancer from our prospective cohort of 8640 HIV-seropositive individuals.

Results

In our cohort of 8640 HIV-seropositive individuals, the incidence of invasive anal cancer (diagnosed in 26 patients) is 60 per 100,000 patient-years. This is 120 times higher than in the age- and gender-matched general population.

The incidence of invasive anal cancer in the HIV cohort was 35 per 100,000 patient-years of follow-up in the pre-HAART era (1984-1995) and 92 per 100,000 patient-years of follow-up in the post-HAART era (1996-2003).

These figures are significantly higher than those for the general population (P < 0.001 for both) and give a relative risk of 67 and 176 in the pre- and post-HAART eras, respectively, compared with the general population.

The 5-year overall survival is 47%, and the 5-year disease-free survival is 66%. There is no difference in overall survival between the pre- and post-HAART eras (log rank P = 0.19).

Conclusions

In conclusion, the authors note, “Unlike other HIV-associated cancers, there has been no significant change in the incidence, clinical features, or overall survival since the introduction of HAART.”

Discussion

Although there has been no significant change in the incidence since the start of 1996 when HAART was introduced into standard care for patients in our cohort, there is a trend toward an increasing incidence. This finding is in marked contrast to the declines in KS and NHL.

One explanation for this is the lack of clear correlation between anal cancer incidence and falling CD4 cell count. Moreover, HAART does not cause regression of anal intraepithelial neoplasia (AIN), the presumed precursor of invasive anal cancer.

In the case of cervical cancer, the progression from infection to invasive cervical cancer takes 10 to 20 years. Certainly, the prolonged survival of people with HIV in the HAART era may account for the trend toward an increasing incidence of anal cancer, because people are now living long enough for this progression to invasive anal cancer to occur.

There are no major differences between patients diagnosed in the pre- and post-HAART eras, suggesting little or no influence of HAART on the biology of the disease.

In this cohort, the overall survival at 5 years is 47%, whereas the anal cancer disease-free survival at 5 years is 66%. The 2-year survival rate is 74%, however, with no relapses of anal cancer occurring after this time, and all deaths after this time point are attributed to HIV infection.

These results are particularly encouraging because they include 2 (8%) patients who received palliative care only. Moreover, 9 of the patients had locally advanced disease, and this is associated with 5-year survival rates of less than 50% in the general population.

12/10/04

Reference
M Bower and others. HIV-Associated Anal Cancer: Has Highly Active Antiretroviral Therapy Reduced the Incidence or Improved the Outcome? Journal of Acquired Immune Deficiency Syndromes  37(5): 1563-1565, December 15, 2004.

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