Infrared therapy could help prevent anal cancer in HIV-positive population

By Caroline Price, Senior medwireNews Reporter

Infrared coagulopathy (IRC) treatment of a potential precursor of anal cancer is effective and warrants further study as a way to reduce anal cancer incidence and mortality among HIV-infected people, report researchers.

In a study of HIV-positive patients found to have high-grade anal intraepithelial neoplasia (HGAIN) through a primary care screening program, those who underwent the IRC treatment were significantly less likely to have such histopathology 1-2 years later than were untreated patients.

Importantly, and in contrast to the untreated group, none of the patients treated with IRC progressed to anal squamous-cell carcinoma (SCC), "which is the goal of surveillance and treatment," authors Stephen Weis (University of North Texas, Fort Worth, USA) and colleagues point out.

As reported in Diseases of the Colon and Rectum, their study included 124 HIV-infected patients with HGAIN, identified during routine screening for human papillomavirus disease using high-resolution anoscopy.

Of 42 patients who were untreated, or underwent delayed IRC treatment, 37 (88%) had HGAIN and two (5%) had developed SCC at final histology evaluation a mean of 1.8 years after initial HGAIN detection.

By contrast, 73 (74%) of 98 patients who underwent immediate IRC had no evidence of HGAIN at final histology evaluation after a mean of 1.3 years, and none had progressed to SCC.

Fifteen of those who had not responded post-treatment underwent additional IRC and 12 (80%) of these had low-grade AIN on re-evaluation afterwards, while three still had HGAIN.

Overall, 85 (87%) patients had no evidence of HGAIN after completing initial and, if necessary, follow-up IRC treatment.

"Although the short duration of follow-up and small number of cancers that occurred in this study do not allow an inference that IRC affects the incidence of anal SCC, the rate of progression to SCC in our study is consistent with rates reported in immunocompromised populations from earlier studies and adds further support to the concept that HIV-infected patients with HGAIN are at increased risk for developing anal cancer," Weis and colleagues reason.

They also say that, although this was not a randomized study, the untreated patients represented a comparable "control group."

The researchers note that IRC is well-tolerated and can be performed on an outpatient basis with local anesthesia, and that it is much less likely to cause complications than surgical excision of AIN.

"These data support the premise that HGAIN treatment can be effective and can prevent the progression to anal SCC in HIV-infected persons," they conclude.

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