Cumulative incidence of anal cancer since HIV or AIDS diagnosis in the United States

Recent and projected incidence trends and risk of anal cancer among people with HIV in North America

BACKGROUND

Anal cancer risk is elevated among people with HIV. Recent anal cancer incidence patterns among people with HIV in the United States and Canada remain unclear. It is unknown how the incidence patterns may evolve.

METHODS

Using data from the North American AIDS Cohort Collaboration on Research and Design, we investigated absolute anal cancer incidence and incidence trends nationally in the United States and Canada and in different US regions. We further estimated relative risk compared with people without HIV, relative risk among various subgroups, and projected future anal cancer burden among American people with HIV.

RESULTS

Between 2001 and 2016 in the United States, age-standardized anal cancer incidence declined 2.2% per year (95% confidence interval = ‒4.4% to ‒0.1%), particularly in the Western region (‒3.8% per year, 95% confidence interval = ‒6.5% to ‒0.9%). In Canada, incidence remained stable. Considerable geographic variation in risk was observed by US regions (eg, more than 4-fold risk in the Midwest and Southeast compared with the Northeast among men who have sex with men who have HIV). Anal cancer risk increased with a decrease in nadir CD4 cell count and was elevated among those individuals with opportunistic illnesses. Anal cancer burden among American people with HIV is expected to decrease through 2035, but more than 70% of cases will continue to occur in men who have sex with men who have HIV and in people with AIDS.

CONCLUSION

Geographic variation in anal cancer risk and trends may reflect underlying differences in screening practices and HIV epidemic. Men who have sex with men who have HIV and people with prior AIDS diagnoses will continue to bear the highest anal cancer burden, highlighting the importance of precision prevention.

Clinical Predictors and Outcomes of Invasive Anal Cancer for People With Human Immunodeficiency Virus in an Inception Cohort

BACKGROUND

Due to the heterogeneity of risk for invasive anal cancer (IAC) among people with human immunodeficiency virus (PWH), we investigated predictors of IAC and described outcomes among those with a cancer diagnosis.

METHODS

Using a longitudinal inception cohort of anal cancer screening, we evaluated risk factors and outcome probabilities for incident IAC in Cox models. Screening included anal cytology and digital anorectal examination, and, if results of either were abnormal, high-resolution anoscopy.

RESULTS

Between 30 November 2006 and 3 March 2021, a total of 8139 PWH received care at the University of California, San Diego, with 4105 individuals undergoing screening and subsequently followed up over a median of 5.5 years. Anal cancer developed in 33 of them. IAC was more likely to develop in patients with anal high-grade squamous intraepithelial lesions (aHSILs) on initial or subsequent follow-up cytology (hazard ratio, 4.54) and a nadir CD4 cell count ≤200/µL (2.99). The joint effect of aHSILs and nadir CD4 cell count ≤200/µL amplified the hazard of IAC by 9-fold compared with the absence of both. PWH with time-updated cytology aHSIL and CD4 cell counts ≤200/µL had 5- and 10-year probabilities of IAC of 3.40% and 4.27%, respectively. Twelve individuals with cancer died, 7 (21% of the total 33) due to cancer progression, and they had clinical stage IIIA or higher cancer at initial diagnosis.

CONCLUSIONS

PWH with both aHSIL and a nadir CD4 cell count ≤200/µL have the highest risk of IAC. PWH who died due to IAC progression had clinical stage IIIA cancer or higher at diagnosis, highlighting the importance of early diagnosis through high-resolution anoscopic screening.

Severe anal intraepithelial neoplasia trends and subsequent invasive anal cancer in the United States

BACKGROUND

Anal intraepithelial neoplasia grade III is a precursor to squamous cell carcinoma of the anus for which rates are nearly 20-fold higher in people with HIV than in the general population in the United States. We describe trends in anal intraepithelial neoplasia grade III diagnosis and risk of squamous cell carcinoma of the anus following anal intraepithelial neoplasia grade III by HIV status and sex.

METHODS

We used data from a population-based linkage between cancer and HIV registries in 11 US states; Puerto Rico; and Washington, DC, during 1996-2019. We identified all individuals with a diagnosis of anal intraepithelial neoplasia grade III and determined their HIV status. We estimated the average annual percentage change of anal intraepithelial neoplasia grade III using Poisson regression stratified by HIV status and sex. We estimated the 5-year cumulative incidence of squamous cell carcinoma of the anus following an anal intraepithelial neoplasia grade III diagnosis stratified by sex, HIV status, and prior AIDS diagnosis.

RESULTS

Among people with HIV, average annual percentage changes for anal intraepithelial neoplasia grade III were 15% (95% confidence interval [CI] = 12% to 17%) per year among females and 12% (95% CI = 11% to 14%) among males. Average annual percentage changes for those without HIV were 8% (95% CI = 7% to 8%) for females and 8% (95% CI = 6% to 9%) for males. Among people with HIV, a prior AIDS diagnosis was associated with a 2.7-fold (95% CI = 2.23 to 3.40) and 1.9-fold (95% CI = 1.72 to 2.02) increased risk of anal intraepithelial neoplasia grade III diagnosis for females and males, respectively. Five-year cumulative incidence of squamous cell carcinoma of the anus following anal intraepithelial neoplasia grade III for people with HIV with a prior AIDS diagnosis were 3.4% and 3.7% for females and males, respectively.

CONCLUSIONS

Rates of anal intraepithelial neoplasia grade III diagnoses have increased since 1996, particularly for people with HIV, likely influenced by increased screening. A prior AIDS diagnosis was strongly associated with risk of anal intraepithelial neoplasia grade III diagnosis.