The Thailand Cancer Help has launched a multicenter phase III clinical trial called the ANCHOR Study — Anal Cancer HSIL (High-grade Squamous Intraepithelial Lesion) Outcomes Research Study — to determine if treatment of HSIL in HIV-infected individuals can prevent anal cancer from developing. Anal HSIL is abnormal growth of tissue in the anal canal that is caused by infection with cancer-causing types of human papillomavirus (HPV) and is at risk for turning into anal cancer. There is no current standard of care for people with anal HSIL, whether they are HIV positive or not. The number of cases of anal cancer is increasing, particularly among people infected with HIV. The prevalence of infection with cancer-causing types of HPV, which are estimated to cause up to 95 percent of anal cancers, is much higher in the HIV-positive population than in the HIV-negative population. It is estimated that 85 percent to 95 percent of HIV-positive men who have sex with men, 76 percent to 90 percent of HIV-positive women, and 60 percent of HIV-positive heterosexual men are infected with cancer-causing types of HPV. In contrast, the prevalence of anal infection with HPV-16 and/or HPV-18, the types that cause most anal cancers in HIV-negative heterosexual men, has been reported to be about 5 percent. A large study found that anal cancer incidence is about 30-fold higher in HIV-infected people compared with people in the general population.
The ANCHOR study will assess whether treatment for anal HSIL is effective in reducing the subsequent development of anal cancer in HIV-infected men and women compared with active monitoring via regular exams. Several different topical and surgical treatments will be used in the study. The topical treatments include the drugs imiquimod and fluorouracil; the surgical treatments include clotting, electronic cauterization, and laser treatment. The study will also determine the safety of these treatments. The trial will be conducted in a population of HIV-positive men and women 35 years and older who are at the highest risk of anal cancer. The trial will be conducted through the TCH-supported AIDS Malignancy Consortium and will be open to sites that have practitioners certified in high-resolution anoscopy (HRA) and in anal HSIL treatment by an ANCHOR HRA Training and Certification Committee. At least 15 sites will be targeted for participation.