Just as use of Pap smears has led to a dramatic drop in cervical cancer, so screening for anal cancer among gay and bisexual men would save many lives at a reasonable cost, according to a study conducted at the Harvard School of Public Health and University of California at San Francisco. Anal squamous cell cancer and cervical cancer are similar diseases, both caused by a sexually-transmitted virus called human papillomavirus (HPV).
The study, led by Sue Goldie, MD, assistant professor of Health Policy and Decision Science, at the Center for Risk Analysis, Harvard School of Public Health, predicts that the use of a simple and inexpensive procedure, comparable to a Pap smear, would lead to detection of pre-cancerous lesions among high-risk, HIV-negative men and allow for removal of these lesions and early treatment of anal cancer. A study by the same scientists last year reported similar findings for HIV-positive gay men.
The new research is reported in the June 1 issue of The American Journal of Medicine. The issue includes a supporting editorial written by Paul Volberding, MD, UC San Francisco professor of medicine at the UCSF-affiliated San Francisco General Hospital Medical Center.
Senior author of the study, Joel Palefsky, MD, says, "No one knew that cervical cancer was preventable before the use of Pap smears became widespread in the 1960s and cut the incidence of the disease by 80 percent. The hope is that a simple, early screening procedure for HPV-induced anal cancer would lead to a similar drop in disease and death." Palefsky is professor of laboratory medicine and of medicine at UC San Francisco.
Available statistics indicate that up to 35 gay men per 100,000 develop this form of anal cancer per year, the researchers report -- a figure comparable to the 40 women per 100,000 who contracted cervical cancer in the U.S. before the use of Pap smears.
The new model, based on current clinical evidence, predicts that anal Pap smear screening every two to three years would cost about $16,000 "per year of life gained, adjusted for quality of life." By comparison, annual mammography has been reported to cost approximately $120,000 per year of life gained. The analysis draws on the scientific information gained from cervical cancer screening and is based on health and other epidemiological data from large samples of at-risk men in San Francisco and Seattle.
The study does not conclude that practitioners should immediately begin offering the simple screening procedure. The investigators caution, "Before we proceed, we must first replicate the data we have from Seattle and San Francisco in other populations, to be able to dismiss the possibility that the disease pattern in these cities is unique." They also note that while the screening test is simple and appears reliable, it is not in widespread use and training of medical workers will have to be expanded to make the test more widely available. In addition, research is needed to determine the optimal surgical procedures to treat the pre-cancerous lesions.
The study was funded by the Agency for Health Care Policy and Research, the General Clinic Research Center at the University of California, San Francisco with funds provided by the Division of Research Resources (5 MO1-RR-00079), US Public Health Service, and by the National Cancer Institute (grant R01 CA 54053).