Today, a guest post, written by Dr. Robbie Goldstein:
“Whether due to increased recognition and screening or changing patterns of infection and pathogenesis, rates of anal cancer (caused almost exclusively by the human papilloma virus, HPV) are increasing significantly in the United States. While rates among men who have sex with men (MSM) are high, rates among HIV-positive MSM are staggering. To provide some numbers: the incidence of anal cancer in the general population is 2/100,000; in the HIV-negative MSM population, the incidence is 40/100,000, but in the HIV-positive MSM cohort, the rate soars to 75-130/100,000. For comparison, the rates of commonly screened for cancers in the general population are as follows: breast cancer 122/100,000 (women), prostate cancer 128/100,000 (men) and colorectal cancer 39.9/100,000.
While there are no data to show that anal cancer screening with anal pap smears and subsequent high resolution anoscopy (HRA) will decrease the rates of anal cancer, experts have extrapolated data from cervical cancer screening. Interestingly, there has never been a randomized trial of cervical pap smear screening to support its routine use in primary care, although it is hard not to acknowledge the effect routine screening has had on decreased rates of cervical cancer: rates among women in the 1940s (before routine pap smears) were as high as 32/100,000, but have dropped to 7.8/100,000 in the modern era.
To help answer the question of whether there is any benefit to anal cancer screening and HRA, a multi-center study lead by Dr. Joel Palefsky at UCSF is now underway. The ANCHOR Study (Anal Cancer/HSIL Outcomes Research Study) intends to enroll patients found to have anal dysplasia on pap smear (specifically, HSIL or high-grade squamous intraepithelial lesion). These study participants will be randomized to receive treatment with one of a variety of methods or observation and then followed for the next 5 years to determine the rates of progression to anal cancer.
The study is currently recruiting across the country and seeks to determine whether treatment for high-grade lesions is necessary. While the root question will remain unanswered, that is whether there is an overall benefit to anal dysplasia screening with anal pap smears, the ANCHOR Study may be a pivotal step in the effort to reverse the national trends in anal cancer and will hopefully provide guidance to primary care and HIV physicians who care for the MSM population.”