A basic connection of statistics lead a researcher at Women & Infants Hospital of Rhode Island to question whether women should be screened for anal cancer during a regular visit to the gynecologist, and what technique is most effective.
Anal cancer is rare in the United States, with only about 3,200 new cases in women estimated in 2010, but it is one of the few cancers where the numbers have been steadily rising. Existing research has also demonstrated an association between anal cancer and the human papilloma virus (HPV), which is a known cause of cervical cancer. In fact, HPV infection is related to 90% of anal cancers in women, which suggests that the majority of anal cancers could be prevented with the HPV vaccine.
Katina Robison, MD, a gynecologic oncologist with Women & Infants' Program in Women's Oncology and one of the hospital's Women's Reproductive Health Research (WRHR) Scholars, has launched recruitment for her new study, "Anal cytology and HPV genotyping in women with lower genital tract neoplasia." The two-year study is funded by a $20,000 seed grant from the Brown University Center for Women's Excellence.
"There is no literature currently suggesting how this should be handled in the general population. Should we test everyone? Who is at risk?" Dr. Robison said. "My goal is to gather basic information that I can use to design a larger, multi-site study that will analyze the sensitivity and specificity of anal cytology, which is basically a Pap of the anus, with the possible addition of HPV testing, to screen at-risk women."
Laying the groundwork
There are three goals to the current study:
- To determine the prevalence of abnormal anal cytology among women with a recent history of cervical, vulvar or vaginal high-grade pre-cancer or cancer
- To determine the prevalence of high-risk anal HPV among women with a recent history of cervical, vulvar or vaginal high-grade pre-cancer or cancer
- To compare the prevalence of abnormal anal cytology and high-risk HPV between at-risk and low-risk women
If her hypotheses are correct, it could change the way gynecologists conduct regular examinations of their patients with a history of cervical pre-cancer or cancer. Currently, they perform detailed exams of the vulva and vagina in these women, but do not routinely examine the anus.
"The goal of screening is to detect and treat anal dysplasia early, thereby preventing anal cancers," Dr. Robison said, adding that screening can be as simple as a Pap test designed for the anus.
Women will be considered eligible for the study if they are over 18 and have had a diagnosis of cervical, vulvar or vaginal cancer diagnosed through a biopsy within two years.
Dr. Robison hopes to enroll a total of 348 women with cancer and an additional 116 control subjects in the study. They will be recruited through the Program in Women's Oncology and the hospital's Center for Primary Care.
All participants will undergo cervical and anal cytologic screening and HPV genotype evaluation of the cervix, vulva and anus. Patients with cervical and anal cytologic abnormalities will be managed according to American Cancer Society guidelines. If an abnormal anal cytology is discovered, the patient will be referred to the Rhode Island Colorectal clinic.
"By looking at a larger group with a control, we'll be able to better decide if everyone should have anal cancer screenings. We will also be able to determine if HPV testing may be a useful screening tool," Dr. Robison said.