In a groundbreaking finding, a new study led by UC San Francisco found that routine screening for and removal of precancerous anal lesions can significantly reduce the risk of anal cancer, similar to the way cervical cancer is prevented in women.
The national study is published June 16, 2022, in the New England Journal of Medicine.
"This is the first randomized controlled trial showing that treatment of anal precursor lesions is effective in reducing progression to anal cancer, with progression approximately 60 percent lower in the treatment arm."
Joel Palefsky, MD
“Anal cancer is among a limited number of cancers that are potentially preventable through treatment of known cancer precursors,” said lead author Joel M. Palefsky, MD, a professor of medicine in the Department of Infectious Diseases at UCSF. “This is the first randomized controlled trial showing that treatment of anal precursor lesions is effective in reducing progression to anal cancer, with progression approximately 60 percent lower in the treatment arm.”
Palefsky established the world’s first clinic devoted to prevention of anal cancer in 1991 at UCSF. Called the UCSF Anal Neoplasia Clinic Research and Education Center, it is currently housed at the UCSF Medical Center at Mount Zion in San Francisco.
He was lead investigator of the seminal trial, known as the ANCHOR Study (Anal Cancer/HSIL Outcomes Research). The trial was performed at 25 clinical sites around the country.
Due to the statistically significant nature of the findings, the study was stopped last year. Primary findings were presented at the Conference on Retroviruses and Opportunistic Infections (CROI) in February 2022. The NEJM paper is the first time that data have been published in a scientific journal.
Though anal cancer is rare in the general population, cases have been increasing in the U.S. and other developed countries in recent decades.
Anal cancer is caused by human papillomavirus (HPV), which can cause changes to the skin inside and around the anus known as high grade squamous intraepithelial lesions (HSIL). Similar to cervical cancer, anal cancer is preceded by HSIL. The cell changes often disappear on their own, but some develop into anal cancer, a disease that can have no symptoms at its earliest stages and frequently people are unaware of having it. Anal cancer may be mistaken for hemorrhoids, and by the time it’s diagnosed, it may have spread elsewhere.