Although rare, a significant increase in incidence and mortality of anal cancer has been observed since 1975. In 2013, there were an estimated 7,060 new cases of anal cancer, of which 62% were in women.1 Women with human papillomavirus (HPV)-related cervical dysplasia are at risk for anal intraepithelial neoplasia and anal cancer.2,3
Cervical and anal cancers are strongly associated with oncogenic types of HPV.3 It is known that persistent high-grade squamous intraepithelial lesions are a risk factor for developing cervical cancer, but it is hypothesized that they may also be precursors to anal cancer.4 Women with high-grade cervical dysplasia and concurrent anal HPV may be at higher risk of HPV reinfection, leading to persistence of cervical dysplasia.2,5 The benefits of established screening for cervical dysplasia in reducing the overall incidence of invasive cervical cancer is well documented. High-risk HPV DNA is detected in 90–100% of women with cervical and 90.8% of women with anal cancers.6 Currently, there are no established guidelines endorsed by the U.S. Preventative Services Task Force for anal screening for precancerous anal lesions.4
This was a descriptive study to quantify the correlation between cervical dysplasia and anal HPV. Secondarily, we wished to examine the relationship between severity of cervical dysplasia and presence or absence of anal HPV and anal dysplasia. The prevalence in the population is unknown. This study was an exploratory analysis to look at this question.
MATERIALS AND METHODS
This was a prospective cohort study performed at a tertiary medical center on patients referred to the dysplasia clinic for evaluation of abnormal Pap test results. Our study population included military personnel and their dependents. The study was approved by the institutional review board at Naval Medical Center San Diego before initiation of the study. Voluntary informed consent was obtained. Evaluation included colposcopy and possible sampling of tissue from the cervical canal or cervix. Patients with referral Pap test results showing atypical squamous cells of undetermined significance with HPV (ASC-US/HPV+), atypical squamous cells (cannot rule out high grade dysplasia [ASC-H]), low-grade squamous intraepithelial lesions (LSIL), and high-grade squamous intraepithelial lesions (HSIL) were eligible for inclusion in this study. Patients with ASC-H, LSIL, and HSIL referral Pap test results also were tested for cervical HPV at the time of colposcopy. Exclusion criteria included women aged younger than 21 years, current pregnancy, human immunodeficiency virus (HIV)–positive status, atypical glandular cells, or prior total hysterectomy with surgical absence of the cervix. Human immunodeficiency virus testing was not done as part of our study. Only patients with known HIV at the time of colposcopy were excluded.
A sample size of 200 patients was chosen. At the time of the study design, data were not available on the prevalence of anal HPV and anal dysplasia in the general population. As a result of this, we were unable to determine the actual sample size required to adequately power all aspects of our study. We chose a sample size of 200 based on prior sample sizes noted in the initial studies on anal HPV in women. Additionally, our dysplasia clinic sees approximately 300 patients per month so a sample size of 200 patients appeared to be an achievable goal for our initial study.
After obtaining written consent, colposcopy was performed with endocervical curettage and cervical biopsies as per routine. Patients were recruited for the study during the spring and summer of 2012. At that time, high-risk HPV testing was performed routinely only on ASC-US Pap test results. For purposes of our study, in all patients other than those with ASC-US+HPV referral Pap test results (patients with LSIL and HSIL referral Pap test results), the cervix was tested for HPV at the time of colposcopy and anal HPV testing and cytology. For purposes of this study, patients with LSIL and HSIL referral Pap test results were tested for cervical HPV at the time of colposcopy using a Dacron swab, similar to the manner in which the anal HPV was tested. An anal swab was then obtained by trained subinvestigators and sent for anal HPV and liquid-based cytology. Subinvestigators included obstetrics–gynecology residents rotating through the dysplasia clinic and the clinic's oncology staff. All individuals performing this testing first watched an instructional video and were supervised by the oncology staff until they were deemed competent. Anal swabs were obtained by using a water-moistened Dacron swab, which was gently inserted just proximal to the anorectal transformation zone. The swab was then withdrawn with lateral pressure in a spiral motion to sample the circumference of the anal canal.
The anal swabs were analyzed in a similar fashion to cervical HPV specimens. The swabs were collected and placed in Thin Prep fluid media. The specimen was sent to the laboratory for processing and anal cytology was performed in-house by pathologists in a manner similar to that used for our cervical cytology and HPV testing. Samples were sent to the laboratory without any corresponding information on the patient's cervical dysplasia status to control for potential analysis bias. Human papillomavirus testing is U.S. Food and Drug Administration-approved and validated only for cervical samples. A waiver was obtained from the U.S. Food and Drug Administration for anal HPV testing for the purposes of this study. Human papillomavirus testing was reported only as the presence or absence of high-risk HPV types. A DNA probe cocktail specific for intermediate- or high-risk serotypes is used and reported as “not detected” or as “detected” for high-risk HPV serotype. This study did not examine specific HPV subtypes and analysis of specific strains of HPV was not the objective of our study so we did not expand our testing beyond that which is routinely available at our facility.
Patients with positive anal cytology were referred to the department of colorectal surgery for high-resolution anoscopy and biopsy if indicated. They will be followed by the department of colorectal surgery for long-term follow-up for anal dysplasia if indicated by their anoscopy results. Evaluation of these patients is still ongoing; at this time, the number of patients who have undergone biopsy is too small to analyze.
Two hundred one patients were enrolled in the study with 196 patients eligible for evaluation. Five patients were excluded. Two had referral Pap test results that did not meet inclusion criteria (one atypical glandular cells of undetermined significance Pap test result and one normal Pap test result on post–loop electrosurgical excision procedure [LEEP] surveillance). Three patients had atypical glandular cells of undetermined significance referral Pap test results. Within each subgroup there were additional insufficient samples. Patients with insufficient samples were not included in that specific subgroup analysis only.
Table 1 breaks down the age of the patients in our study by their anal Pap test results. The average age of participants was 29.5 years old. Fifty percent of the patients with anal Pap test results were aged 21–25 years. Table 2 provides additional demographic data collected on the 170 patients whom anal cytology results were available. Thirty-six of the 170 available patients (21.18%) were current or prior tobacco users. Ten of the patients had prior interventions including LEEP (eight) and cold knife cone (two) patients. No patients had prior cryotherapy. Our study did not collect information regarding number of partners or sexual practices of our patients. Seventy-nine of our original 196 patients (40.3%) were referred with ASC-US Pap test results with positive HPV, 11 (5.6%) with ASC-H, 84 (42.9%) with LSIL, and 22 (11.2%) with HSIL. Of all patients tested for cervical high-risk HPV at the time of the study (ASC-US+HPV referral Pap test results excluded), 113 had positive high-risk HPV at the time of colposcopy (80.7%).
As noted in Table 3, one hundred thirty-five of the 196 study patients underwent cervical biopsies available for evaluation. Fifty-nine (30.4%) patients did not clinically require a cervical biopsy at the time of biopsy. Two patients had an insufficient sample. Of those who were biopsied, 61 (31.4%) had negative biopsies, 42 (21.7%) had cervical intraepithelial neoplasia (CIN) 1, and 32 (16.5%) had CIN 2 or 3. One hundred twenty-four patients had endocervical curettage at the time of colposcopy. Of those, 113 (57.4%) had a normal endocervical curettage, six (3.1%) had endocervical curettage with CIN 1, and five (2.6%) had endocervical curettage with CIN 2 or 3. The remainder had insufficient samples (five) or biopsies were not indicated (66) at the time of colposcopy. Eighteen patients had a LEEP during the study time period. Of those, four (2%) had negative LEEP, one (0.5%) had CIN 1, and 12 (6.1%) had CIN 2 or 3. There was one insufficient LEEP sample.
All the patients enrolled in our study had anal Pap tests. However, 26 had insufficient samples (15%). The 170 patients who had anal cytology available for analysis are shown in Table 4. Of those, 140 (82.4%) had negative anal Pap test results, 20 (11.8%) had ASC-US, and 10 (5.9%) had LSIL. The overall prevalence of abnormal anal cytology was 17.6% of the 170 samples analyzed.
Women referred to the dysplasia clinic had a 32.5% (95% confidence interval [CI] 0.26–0.40) incidence of high-risk anal HPV and a 17.6% (95% CI 0.122–0.24) incidence of concurrent abnormal anal cytology. A standard logistic regression was performed as shown in Table 5. Women with high-risk cervical HPV were more likely to have high-risk anal HPV (61) (odds ratio [OR] 3.6, 95% CI 1.19–10.77, P<.024). Women with high-risk anal HPV were more likely to have abnormal anal cytology (30) (OR 6.5, 95% CI 2.74–15.60, P<.001). We also looked to see if women with high-risk cervical HPV were more likely to have abnormal anal cytology (OR 3.6, 95% CI 0.81–15.99, P .93). However, our study was not powered to answer this question.7
High-risk anal HPV was tested for in all study patients. Table 6 compares biopsy-proven cervical dysplasia (broken down by biopsy, endocervical curettage, and LEEP results) to presence or absence of anal HPV. Insufficient samples were not included in this analysis. Table 7 notes the severity of anal cytology results by the presence or absence of high-risk anal HPV.
The oncogenic potential of HPV and its role in development of precancerous cervical squamous intraepithelial lesions and invasive cancer is well studied. The efficacy of widespread screening with cervical Pap tests is proven. There is a growing body of evidence to suggest that in addition to being at higher risk of developing cervical cancer, women with high-grade cervical dysplasia may have an elevated risk of anal cancer.4,7,8
The New York State Department of Health AIDS Institute recommends an anal Pap test annually for HIV-positive men who have sex with men and for HIV-positive women with a history of cervical cancer.9 Few studies have addressed the role of screening for the important high-risk group comprised of women with high-risk cervical abnormalities without a history of HIV. Recent studies have begun to emerge indicating the link between cervical and anal cancer and the role of high-risk HPV. Women with HPV-related cervical dysplasia are a high-risk group for anal intraepithelial neoplasia and anal cancer.2 Prior studies have looked at various risk factors such as age, parity, age at first intercourse, number of sexual partners, and reported anal intercourse in relation to cervical and anal cytology.2,10,11
A recent study in 2011 estimated the prevalence of cytologic abnormalities of the anal mucosa in women with positive cervical cytology.5 In a population of 49 patients, they showed a high prevalence of concurrent anal squamous intraepithelial lesions in women with cervical dysplasia (59.2%).5
Although the number of insufficient anal Pap tests appears high at 13%, it is interesting to note that a recent Letter to the Editor in Gynecology Oncology addressed the question of insufficient samples and quoted a 9–17% insufficient sample size as an acceptable rate.12
Of the 196 high-risk patients we analyzed in our patient population, we found a 32.5% prevalence of anal HPV and a 17.6% prevalence of abnormal anal cytology. We choose to include all abnormal cytology (ASC-US and greater) in our analysis as opposed to only HSIL results to establish a baseline. A 2005 study by Arain et al noted that 46% of their ASC-US and 56% of LSIL Pap test results showed anal intraepithelial neoplasia 2–3 on biopsy, which was consistent with prior studies.13 They recommended that all anal cytology ASC-US and greater be referred for anoscopy.
Studies have shown that women with CIN 3 have a relative risk of anal cancer that is five times greater than those without.8 In women with confirmed genital intraepithelial neoplasia, there was a greater than 10% prevalence of anal intraepithelial neoplasia.4 The National Cancer Institute's Surveillance, Epidemiology and End Results program from 1973 to 2007 showed a standardized incidence ratio of 16.4 for the incidence of anal cancer in women with in situ cervical cancer and a 6.2 incidence ratio for anal cancer in women with invasive cervical cancer.7 None of these studies explored the association of high-risk HPV status to the incidence of anal dysplasia, a presumed precursor to anal cancer. Our study was novel in looking at the relationship between anal HPV and anal cytology specifically in women referred for colposcopy. Larger longitudinal studies will be required to determine the rate of clearance or persistence. Additionally, correlating the histology would be the next natural phase of the study.
Although the power of our study was limited by our sample size of 200 patients, it was unique in looking at a population specifically at risk given their known cervical abnormalities. At this time, the natural progression of anal dysplasia in relation to the onset of cervical dysplasia is yet unknown. As our patients are followed over time, this relationship may become clearer. Recently it has been proposed that anal cytology is not a completely effective screening tool and that anoscopy is not only the gold standard for diagnosis, but should also be used for screening.4 That study did not look at HPV testing as a screening tool, which given its recent emergence as an important aspect of cervical cancer screening suggests that a role may also exist in anal cancer screening. Several population-based studies have indicated that although there is an increased risk of anal cancers in women with HPV-related gynecologic cancers, a decade or more may pass before anal cancers are found in these women.6,8 Long-term analysis of our patients will be required to optimize the timing and methodology of anal cancer screening.
2. Valari O, Koliopoulos G, Karakitsos P, Valasoulis G, Founta C, Godevenos D, et al.. Human papillomavirus DNA and mRNA positivity of the anal canal in women with lower genital tract HPV lesions: predictors and clinical implications. Gynecol Oncol 2011;122:505–8.
3. Moscicki AB, Schiffman M, Kjaer S, Villa L. Chapter 5: Updating the natural history of HPV and anogenital cancer. Vaccine 2006;24(suppl 3):S3/42–51.
4. Santoso JT, Long M, Crigger M, Wan JY, Haefner HK. Anal intraepithelial neoplasia in women with genital intraepithelial neoplasia. Obstet Gynecol 2010;116:578–82.
5. Calore E, Giaccio C, Nadal S. Prevalence of anal cytologic abnormalities in women with positive cervical cytology. Diagn Cytopathol 2011;39:323–7.
6. Jiménez W, Paszat L, Kupets R, Wilton A, Tinmouth J. Presumed previous human papillomavirus (HPV) related gynecological cancer in women diagnosed with anal cancer in the province of Ontario. Gynecol Oncol 2009;114:395–8.
7. Saleem AM, Paulus JK, Sharpter AP, Baxter NN, Roberts PL, Ricciardi R. Risks of anal cancer in a cohort with human papillomavirus-related gynecologic neoplasm. Obstet Gynecol 2011;117:643–9.
8. Edgren G, Sparén P. Risk of anogenital cancer after diagnosis of cervical intraepithelial neoplasia: a prospective population-based study. Lancet Oncol 2007;8:311–6
10. Moscicki AB, Hills N, Shiboski S, Darragh T, Jay N, Powell K, et al.. Risk factors for abnormal anal cytology in young heterosexual women. Cancer Epidemiol Biomarkers Prev 1999;8:173–8.
11. Goodman M, Shvetsov Y, McDuffie K, Wilkens L, Zhu X, Thompson P, et al.. Sequential acquisition of human papillomavirus (HPV) infection of the anus and cervix: the Hawaii HPV cohort study. J Infect Dis 2010;201:1331–9.
12. D'Hauwers K, Tjalma W. Letter to the Editor referring to the manuscript entitled: “Human papillomavirus DNA and mRNA positivity of the anal canal in women with lower genital tract HPV lesions: predictors and clinical implications.” reported by Valari O, et al., (Gynecol Oncol 2011; 122(3): 505-8). Gynecol Oncol 2012;126:499.
© 2014 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.
13. Arain S, Walts A, Thomas P, Bose S. The anal smear: cytomorphology of squamous intraepithelial lesion. Cytojournal 2005;2:4.