HIV and ID Observations

Should every person with HIV over age 35 (if MSM or transgender woman) or 45 (everyone else) have an anal Pap smear, a digital anal rectal exam (DARE), and possibly a high-resolution anoscopy every 1–2 years? According to recent guidelines, yes. But here’s the problem: we don’t know if this screening effort actually prevents cancer.

First, some facts:

1. Human papillomavirus (HPV) infection is necessary, but not sufficient, for the development of anal cancer.
2. Both HPV prevalence and anal cancer incidence are higher in PWH than in those without HIV.
3. The natural history of HPV leading to anal cancer is similar to cervical cancer.
4. Cervical cancer screening programs have reduced incidence of that disease.
5. In the ANCHOR trial, treatment of biopsy-confirmed, high-grade squamous intraepithelial lesions (HSIL) in PWH reduced the risk of anal cancer.

So far, so good.

The temptation, therefore, is to apply our cervical-cancer-prevention model directly to anal cancer, and that’s an approach many have advocated for years. But here’s the problem — there’s no proof this works. As Dr. Hayden Andrews wrote in a recent State-of-the-Art review in Clinical Infectious Diseases (Note: I am currently editor-in-chief of this journal):

To date, no trial has been conducted to determine if anal cancer screening among PWH decreases anal cancer incidence.

And if you think about it for a nanosecond, that’s not surprising! Demonstrating that cancer screening improves outcomes is notoriously hard. Just ask anyone who studies breast, prostate, lung, or colorectal screening — and those cancers are far more common than anal cancer, and have been far more widely studied.

This gets to the core of why I believe the International Anal Neoplasia Society guidelines — later reinforced by the Department of Health and Human Services HIV guidelines — are premature and overly aggressive. They’re posted in our clinic workroom, so I’m constantly reminded of just how broad they are. The recommendations show up in this Bluesky post of mine, along with my incredulous query:

Calling all HIV/ID providers: How many are able to do this screening for anal cancer according to IANS? Including the HRA and repeat screening every 1-2 years (!!) for normal results? Wow, that's a lot of screening tests in a lot of people! #IDSky #HIVsky onlinelibrary.wiley.com/doi/10.1002/…

— Paul Sax (@paulsaxmd.bsky.social) 2025-08-15T17:39:22.614Z

Wow (again) — all MSM and transgender women older than 35? All men and women older than 45? Referral of all abnormal results to high-resolution anoscopy? Then repeat the process if normal results every 1-2 years? My goodness.

Some issues that make broad screening problematic:

• Poor test performance: Anal cytology via Pap smears has low sensitivity for HSIL even in high-prevalence populations; it also has high interobserver variability and lots of unsatisfactory or ASCUS results. Read Dr. Amit Achhra’s paper describing their experience at Yale — disappointing, both in terms of accuracy of anal cytology and patient participation! Digital anal rectal exams (DARE) can pick up anal cancer, but lack sensitivity for HSIL, the key precancerous lesions.
• Limited access to the best test:  High-resolution anoscopy (HRA) is superior to anal cytology, but many clinical sites have few or even no trained providers to do the exams. I know of one site that cares for thousands of patients and has zero access to HRA.
• Patient burden:  Local anaesthesia, discomfort, repeat visits, cost, and anxiety aren’t trivial.
• Unclear screening frequency:  The evidence for how often to screen is even weaker than whether we should screen at all.

Add to this the medicolegal bind these guidelines create — if you follow them, you may overwhelm your local system or excessively burden your patients; if you don’t, you risk looking negligent in hindsight. It’s the perfect recipe for a frustrated group of HIV providers, as we’re doomed to fail (and we obsessive ID types hate failing). I really do wonder what fraction of us are in “compliance” with these guidelines. I’d bet good money it’s very low!

As the late David Sackett, one of the founders of evidenced-based medicine, once wrote, “the fundamental promise we make when we actively solicit individuals and exhort them to accept preventive interventions must be that, on average, they will be the better for it… Without evidence from positive randomized trials … we cannot justify soliciting the well to accept any personal health intervention.”

That’s exactly the unease many of us feel with these guidelines (and thanks to Amit for pointing me to this great quote).

I shared my concerns with Dr. Grant Ellsworth, a member of the DHHS guidelines committee who heads the HPV section, and obviously knows a lot more about this field than I do. In addition to looking forward to a time when HPV testing is routinely incorporated to reduce over-screening, he made some additional valuable comments:

Amit Achhra’s paper really highlights how poor a screening tool cytology can be. They had high unsatisfactory rates and frankly outlying poor performance — even at a place like Yale. If Yale can’t pull it off, who can? My other hesitation with the current recommendations is that I’m not sure ANCHOR’s results can be reproduced in the real world. The study sites had an onerous and expensive training process, with ongoing audits to maintain quality. Sure, we can screen for anal HSIL, but will your clinic be able to find and treat it at the same level as ANCHOR?

That last question is key — if the idealized trial environment can’t be replicated in everyday practice, then the guidelines risk being aspirational rather than accomplishing their goal.

Here’s what I’d do until we have better evidence.

• State up front that although we know that anal cancer is more common in people with HIV, we don’t know if screening helps reduce the risk over a strategy of not screening.
• Start discussions at age 50 (or younger if other strong risk factors:  low nadir CD4, smoking).
• Offer shared decision-making, not automatic screening. What does the patient want? We do this with the PSA, why not this test?
• Skip the anal Pap entirely, and go directly to HRA for those who choose screening. If HRA isn’t available, focus on HPV testing.
• Repeat no more often than every 3-5 years, or some other interval to be determined by baseline risk.

This approach acknowledges that the ANCHOR trial answered only one question — whether treating HSIL reduces cancer incidence. It emphatically did not address the important questions of how to screen, whom to screen, and how often to do it.

I’m afraid answers will only come from further clinical studies.