Risks of Anal Cancer Cut by Half in HIV-Positive Patients with Precancerous Anal Lesion Treatment

Recently, a large-scale clinical trial in people living with HIV found that treating precancerous anal growths known as high-grade squamous intraepithelial lesions reduces the risk of developing anal cancer by more than half.

Studying the Relationship between Anal Lesions and HIV

A large-scale clinical trial from the Anal Cancer/HSIL Outcomes Research study was published in the New England Journal of Medicine, titled "Treatment of Anal High-Grade Squamous Intraepithelial Lesions to Prevent Anal Cancer."

Joel Palefsky, M.D., of the University of California and lead author, says that they have now been able to show for the first time that treating anal HSIL is an effective method of reducing the incidence of anal cancer in a high-risk group of people living with HIV. Rober Yarchoan, M.D, director of the Office of HIV and AIDS Malignancy of the NCI, says that by showing that the HSIL treatment reduces the risks of anal cancer, the study also provides a rationale for screening for HSIL in HIV-positive people.

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Anal Cancer Risks and HIV

Even though anal cancer is relatively rare in the general population, it is the fourth most common form of cancer in people living with HIV. the incidence of anal cancer is roughly 89 per 100,000 in men living with HIV who have to sew with other men between 18.6 and 35.6 per 100,000 in women living with HIV. in comparison, the incidence of anal cancer among the general population is 1.6 per 100,000.

Almost all anal cancer cases are caused by infections of anal cells with cancer-causing types of HPV or human papillomavirus. Suppose the body's immune system does not fight off the infection. In that case, the lingering infection tends to cause cells to become progressively more abnormal, ultimately leading to HSIL and, in severe cases, anal cancer. This progression is similar to what is observed in cervical cancer, also caused by HPV, reports MedicalDialogues.

Despite HPV vaccinations preventing new anal HPV infections, there are currently no evidence-based recommendations to guide screening for and treating anal HSIL.

Routine cervical cancer screening with HPV and Pap testing and removing cervical HSIL have been shown to prevent numerous cases of cervical cancer. On the other hand, it had been unclear whether the treatment of HSIL found through screening similarly prevents anal cancer. Furthermore, treating anal HSIL is significantly more challenging than cervical HSIL treatments, and recurrences are much more common.

The recently concluded ANCHOR study is the first-ever randomized controlled trial to determine whether the treatment of anal HSIL is a safe and effective strategy for reducing the progression of HSIL to anal cancer.

Dr. Palefsky says the data supports treating anal HSIL as the standard of care for those living with HIV at least 35 years and older. He notes that the recent findings could also lead to recommendations for HSIL screening in people living with HIV and may also bring changes to the standard of care for other groups at lower but increased risks of anal cancer, including HIV-negative men who also have sex with other men, and women who have had HPV-related precancers.