Negative Predictive Value of Human Papillomavirus Testing: Implications for Anal Cancer Screening in People Living with HIV/AIDS

Comparison of anal pre-cancer screening strategies among men who have sex with men

PURPOSE

Comparison of anal pre-cancer screening strategies in men who have sex with men (MSM).

METHODS

MSM in the Multicenter AIDS Cohort Study underwent repeated anal cytology (aCyt), oncogenic human papillomavirus (oncHPV) testing. A subset received High-Resolution Anoscopy (HRA). We evaluated three screening strategies for their ability to predict anal histological High-Grade Squamous Intraepithelial lesion (HSIL): single aCyt, sequential aCyt, and oncHPV co-testing. Multivariable logistic regression models evaluated risk of HSIL among participants undergoing HRA within 5 years of screening. Sensitivity and specificity were estimated among participants with HRA, and results corrected for verification bias using weighted generalized estimating equations.

RESULTS

There were 1426 MSM with aCyt screening (48% people with HIV [PWH]) and 428 that underwent HRA. Median age was 57 years, 14% of PWH had CD4< 350 cells/mm3. HSIL probability was higher in MSM with one (39%, p < 0.01) or two abnormal aCyt results (46%, p < 0.01), versus those with normal aCyt (23-24%). Among men with abnormal aCyt, men with oncHPV+ had significantly higher risk than those who were oncHPV- (47% vs. 16%, p < 0.01). Specificity was modest with single aCyt+ (50%) but increased with sequential aCyt+ (79%) or oncHPV+ (67%). Sensitivity was high with single oncHPV+ (88%), moderate with single aCyt+ (66%) and oncHPV+ co-testing (61%), and low with sequential aCyt+ (39%). After correcting for potential verification bias, specificity increased and sensitivity decreased, but inferences were similar.

CONCLUSION

None of the screening strategies evaluated had both sufficient specificity and sensitivity to warrant routine widespread use.

Anal cancer screening and prevention: a review for dermatologists

The incidence of and mortality from anal cancer, predominantly squamous cell carcinoma (SCC), have been increasing since the 1980s, during an era when many common malignancies have seen decreases in mortality. Dermatologists may be more likely to see patients at an increased risk for anal SCC, such as those living with HIV, MSM and those presenting for management of anogenital warts, yet there is little guidance in the field on how to manage these patients. We underwent a project to review the evidence surrounding screening and prevention of anal SCC. HPV vaccination, the main preventative measure for anal SCC, is often underutilized and may not be effective for those most at risk. Screening methods currently include high-risk HPV and anal cytology testing, with high-resolution anoscopy (HRA) reserved for biopsy and confirmatory testing. High-risk HPV testing has been associated with high sensitivity for intraepithelial neoplasia, but low specificity in high-risk groups. Recent meta-analyses examining AIN detection using anal cytology estimate a similarly high sensitivity of 74-87%, with a relatively higher specificity (44-66%) for identifying high-grade AIN. HRA is the gold standard for diagnosis, but its accessibility and cost are deterrents from its use as a screening tool. Cervical cancer screening, initially adopted without significant evidence of its impact, has significantly decreased cervical cancer rates. The argument can be made that rates of anal SCC may also benefit from appropriate screening methods, particularly anal cytology. It is prudent for dermatologists to be aware of the methods available to them in the management of at-risk patients, the data supporting them, and the potential benefits of screening in order to counsel patients appropriately and address the increasing burden of disease.

Screening Women for Anal Cancers: Guidance for Health Care Professionals

Anal cancer is rare in the general population but is steadily increasing in incidence over the past decade especially in women. Identification and screening of women with high risk facilitates detection of anal precancer and early-stage cancer, improves survival, and potentially uses less invasive therapies compared with the conventional chemoradiation treatments used for advanced cancers. No recently published guidelines currently describe details about screening women for anal squamous cell cancer (ASCC). The available evidence supports the existence of groups of women with higher prevalence of ASCC (e.g., women with human immunodeficiency virus, immune suppression, or previous lower-genital high-grade lesion or cancer) who would likely benefit from screening with some combination of anal cytology and human papillomavirus testing. Additional research is needed to establish the cost-effectiveness and the influence of screening on ASCC mortality rates.

Comparing Anal Cancer Screening Algorithms Using Cytology and HPV DNA Testing in Three High-risk Populations

BACKGROUND

Screening strategies for high-risk human papillomavirus (hrHPV)-associated anal cancer are evolving. This study compares the screening performance of anal cytology to hrHPV DNA testing and two novel cytology/hrHPV cotesting algorithms among three high-risk populations.

METHODS

Anal cytology, hrHPV DNA testing, and high-resolution anoscopy (HRA)-guided biopsy results were analyzed from 1,837 participants comprising 1,504 HIV-infected men who have sex with men (MSM), 155 HIV-uninfected MSM, and 178 HIV-infected women. Screening performance to detect histological high-grade squamous intraepithelial lesions (HSIL)/cancer was compared between four strategies with distinct HRA referral thresholds: cytology (ASCUS); hrHPV testing (any hrHPV+); algorithm A (benign cytology/HPV16/18+ or ASCUS/hrHPV+); and algorithm B (benign or ASCUS cytology/hrHPV+).

RESULTS

Histological HSIL/cancer was detected in 756 (41%) participants. Cytology alone had the lowest sensitivity (0.76-0.89) but the highest specificity (0.33-0.36) overall and for each subgroup. Algorithm B was the most sensitive strategy overall (0.97) and for MSM (HIV-infected 0.97; HIV-uninfected 1.00). For HIV-infected women, hrHPV testing and both algorithms yielded higher sensitivity than cytology (0.96, 0.98, and 0.96). Specificity was low for all strategies and subgroups (range 0.16-0.36).

CONCLUSIONS

Screening algorithms that incoporate cytology and hrHPV testing significantly increased sensitivity and further decreased specificity to detect anal precancer/cancer among high-risk populations.