Reports based on a press release in October 2021 suggested it, but now the full data tell the story:
“We now show, for the first time, that treatment of anal HSIL is effective in reducing the incidence of anal cancer,” said Joel Palefsky, MD, lead investigator of the Anal Cancer/HSIL Outcomes Research (ANCHOR) study and founder/director of the Anal Neoplasia Clinic at the University of California, San Francisco. “These data should be included in an overall assessment for inclusion of screening for and treating HSIL as standard of care in people living with HIV.”
Dr. Palefsky presented the full results in a special session at the Conference on Retroviruses and Opportunistic Infections, which drew excitement, gratitude, and relief from both researchers and clinicians, who flocked to the session.
But it’s not just people with HIV who will benefit from this research. Dr. Palefsky suggested that the findings should also be considered as guides for other people at high-risk for anal cancer, such as people who are immunocompromised for other reasons, including those with lupus, ulcerative colitis, Crohn’s disease, or cisgender women who have had vulvar or cervical cancer or precancer.
“If we can show efficacy in the most challenging group of all, which are people living with HIV, we think the results can be as good, if not even better, in the other groups at high risk of anal cancer,” Dr. Palefsky said.
But to serve anyone – whether living with HIV or not – infrastructure, algorithms, and workforce training are going be needed to meet the currently unserved people through use of high-resolution anoscopy (HRA) and other screening technology, he said.
Dr. Palefsy and colleagues screened 10,723 people living with HIV being served at 15 clinics nationwide. More than half, 52.2%, had anal HSIL – 53.3% of the cisgender men living with HIV in the trial, 45.8% of the cis women living with HIV, and a full 62.5% of transgender participants.
Those 4,446 participants were split evenly between the treatment arm and the control arm. Those in the treatment arm received treatment for HSIL on their first study visit via one of five options: hyfrecation, office-based electrocautery ablation, infrared coagulation, topical 5-fluorouracil cream, or topical imiquimod. Then, every 6 months after that, they came in for HRA, blood tests, anal Pap smears, and biopsies to check for any lingering or new HSIL. If clinicians found such cells, they received treatment again. If biopsies still showed HSIL and clinician and participant were worried about cancer, they could come in as frequently as every 3 months and receive treatment each time.
The active-monitoring control group still received an anal Pap smear, blood tests, biopsy, and HRA every 6 months – a level of care that is currently not mandated anywhere for people living with HIV, Dr. Palefsky said in an interview. They were also able to come in for more frequent monitoring (every 3 months) if clinicians were worried about cancer.
“Those in both arms would have been getting more attention than if they had not participated in the study,” he said.
In addition, during screening, researchers found that cancer was already present in 17 other people, who skipped the study to go right to treatment.
Participants reflected the demographics of the HIV epidemic in the United States. They were older (median age, 51 years), mostly gay (78%), and cisgender male (80%). Close to half, 42%, were Black, and 16% were Latinx. In addition, cisgender women made up 16% of the participants and transgender people, and nonbinary individuals accounted for more than 3% of the participants. In addition, one in three smoked.
The vast majority of participants had well-controlled HIV and healthy immune systems, though half in each arm had a history of AIDS, defined as lowest-ever CD4 immune cell counts below 200. Today, more than 80% of participants had undetectable viral loads, defined as a viral load less than 50 copies/mL, and another 7% had HIV viral loads below 200. In total, 9.3% in the treatment arm and 10.9% in the control arm had HIV viral loads higher than that. At time of enrollment, CD4 counts were above 600 in each group, indicating healthy immune systems.
Although all participants were there because they had anal HSIL, more than 1 in 10 – 13% – had abnormal cells so extensive that they covered more than half of the anal canal or the perianal region.
Once everyone was enrolled, researchers began monitoring and treatment, looking specifically for 31 cases of cancer – a number the team had determined that they’d need in order to draw any conclusions. Dr. Palefsky didn’t have to wait long. They were still trying to enroll the last 1,000 participants to have the power necessary to reach that number when the cancer diagnoses came in.
Dr. Palefsky told this news organization that the reason for that is unclear. It could be that some of those cases would have resolved on their own, and so the swiftness with which they reached the required number of cancer cases belies their seriousness. It could also be that the particular people who enrolled in this trial were engaging in behaviors that put them at even higher risk for anal cancer than the population of people living with HIV in the United States.
Or it could be that symptom-based screening is missing a lot of cancers that currently go untreated.
“So perhaps we will be seeing an increase in anal cancer reported in the future compared to the currently reported rates,” he said. “We don’t really know.”
Regardless of the reason for the speed to cases of cancer, the results were definitive: Nine participants were diagnosed with invasive anal cancer in the treatment arm, while 21 were diagnosed with invasive anal cancer in the control arm. That’s a 57% reduction in cancer occurrence between the arms. Or, to put it another way, the rate of anal cancer among people in the treatment arm was 173 per 100,000 people-years. In the active monitoring arm, it was 402 per 100,000 person-years. For context, the overall rate of anal cancer among people living with HIV is 50 per 100,000 person-years. The rate in the general U.S. population is 8 per 100,000 people-years.
The experimental treatment was such a definitive success that the investigators stopped the trial and shifted all participants in the control arm to treatment.