Screening for precancerous lesions can prevent anal cancer

/ Sebastian Kaulitzki, stockadobecom

San Francisco – Early screening and treatment of high-grade anal intraepithelial lesions (HSIL), a precursor to HPV-induced cancer, nearly halved the incidence of anal cancer in a randomized Phase 3 trial of HIV-infected people now in New England Journal of Medicine (NEJM 2022; DOI: 10.1056 / NEJMoa2201048) show the published results.

Like cervical cancer, anal cancers are caused by oncogenic variants of human papilloma viruses (HPV). In both cases there are initially intraepithelial lesions, which gradually develop into carcinoma.

For decades, there has been an effective early diagnosis of cervical cancer, which has led to a significant decline in the incidence of cancer. Such a screening would not be worth it for anal cancer, as cancer is very rare.

One exception is HIV infection, which can become infected during anal sex. In HIV-infected men who have sex with men (MSM), the incidence of anal cancer in the United States is estimated to be 89 / 100,000 person-years, in HIV-infected women the incidence has been determined to be 18.6 and 35.6 / 100,000 person years.

In both groups, HPV-induced cancer is more common in the United States (and probably also in Europe) than cervical cancer in women (7.5 / 100,000 person-years). Regular screening of this risk group may therefore be useful.

As with gynecological cancer screening, screening would specifically look for precursors to a carcinoma. As with cervical cancer, there is initially a “low-grade squamous intraepithelial lesion” (LSIL) – formerly known as CIN1 in cervical screening – from which a “high-grade squamous intraepithelial lesion” (HSIL) may develop, which gynecologists refer to as also CIN2 / 3 and what is the reason for the treatment.

The National Cancer Institute of the United States has been studying in recent years whether early removal of HSIL can prevent the development of anal cancer. The Phase 3 study enrolled 10,723 HIV-infected people aged 35 and over at 25 US centers. HSIL was found in 4,459 participants during high-resolution anoscopy screening.

These were then randomized to immediate treatment or active observation. Treatment for most patients consisted of outpatient electrocautery, in which heat is used to destroy the lesions. In both groups a control anoscopy was performed every 6 months in order to be able to identify and promptly remove a carcinoma.

During a median follow-up of 25.8 weeks, 9 people (173 per 100,000 person-years) were diagnosed with anal cancer in the HSIL immediate removal treatment group compared with 21 people (402 per 100,000 people) in the group. of active observation.

Joel Palefsky of the University of California at San Francisco and collaborators found a 57% lower progression rate that was significant with a 95% confidence interval of 6% to 80%.

According to Palefsky, the results speak clearly in favor of screening and early removal of HSIL, which in the study was associated with only minor side effects: only 7 of the 2,227 patients had severe treatment-related complications such as abscesses (3 patients), pain ( 3 patients) or skin ulceration (1 patient) following topical application of fluorouracil, an alternative treatment to cauterization. © rme /

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