A comparison between cytology and histology to detect anal intraepithelial neoplasia

Anal Squamous Intraepithelial Lesions and Anal Cancer Management in Low Resource Settings

A low resource setting (LRS) is defined as a health care system which does not meet the criteria defined by the World Health Organization (WHO) or other national/international organizations in the following areas: infrastructure, materials, and human resources. 1 Patients encounter barriers which limit their access to care and services that are considered standard of care. While LRS is most commonly associated with developing countries, it is easy to overlook communities in developed countries which lack the financial resources to afford basic health care. This article describes the societal implications and barriers to care for both squamous intraepithelial lesions (SILs) and anal cancer in LRS, the existing screening/surveillance approaches, available treatment approaches to anal cancer, and it also discusses potential evidence-based approaches to bridge the gap for these disparities in anal cancer care.

Implementation of and Early Outcomes From Anal Cancer Screening at a Community-Engaged Health Care Facility Providing Care to Nigerian Men Who Have Sex With Men

PURPOSE

Anal cancer risk is substantially higher among HIV-infected men who have sex with men (MSM) as compared with other reproductive-age adults, but screening is rare across sub-Saharan Africa. We report the use of high-resolution anoscopy (HRA) as a first-line screening tool and the resulting early outcomes among MSM in Abuja, Nigeria.

METHODS

From August 2016 to August 2017, 424 MSM enrolled in an anal cancer screening substudy of TRUST/RV368, a combined HIV prevention and treatment cohort. HRA-directed biopsies were diagnosed by histology, and ablative treatment was offered for high-grade squamous intraepithelial lesions (HSIL). HRA proficiency was assessed by evaluating the detection of squamous intraepithelial lesions (SIL) over time and the proportion biopsied. Prevalence estimates of low-grade squamous intraepithelial lesions and HSIL with 95% CIs were calculated. Multinomial logistic regression was used to identify those at the highest risk of SIL.

RESULTS

Median age was 25 years (interquartile range [IQR], 22-29), median time since sexual debut was 8 years (IQR, 4-12), and 59% (95% CI, 54.2% to 63.6%) were HIV infected. Rate of detection of any SIL stabilized after 200 screenings, and less than 20% had two or more biopsies. Preliminary prevalence estimates of low-grade squamous intraepithelial lesions and HSIL were 50.0% (95% CI, 44.7% to 55.3%) and 6.3% (95% CI, 4.0% to 9.3%). HIV infection, at least 8 years since anal coital debut, concurrency, and external warts were independently statistically associated with SIL.

CONCLUSION

Proficiency with HRA increased with experience over time. However, HSIL detection rates were low, potentially affected by obstructed views from internal warts and low biopsy rates, highlighting the need for ongoing evaluation and mentoring to validate this finding. HRA is a feasible first-line screening tool at an MSM-friendly health care facility. Years since anal coital debut and external warts could prioritize screening.

Colposcopic Characteristics and Lugol's Staining Differentiate Anal High-Grade and Low-Grade Squamous Intraepithelial Lesions During High Resolution Anoscopy

Background

Methods

Results

Conclusions

Management of anal squamous intraepithelial lesions

Anal squamous intraepithelial lesions include both low-grade squamous intraepithelial lesions (LSIL) and high-grade squamous intraepithelial lesions (HSIL) and are caused by chronic infection with the human papillomavirus (HPV). The disease is increasing in both incidence and prevalence, especially among patients with the following risk factors: homosexual men, acquired or iatrogenic immunosuppression, and presence of other HPV-related diseases. Although the natural history of the disease is unknown, there is significant evidence that untreated HSIL progresses to squamous cell carcinoma in 11% of patients and in up to 50% of patients with extensive disease and immunosuppression. Anal cytology and reflex HPV DNA testing are used to screen for disease, particularly among patients with the aforementioned risk factors. Evaluation of the patient should include physical examination and high-resolution anoscopy (HRA) to evaluate for disease above and below the dentate line. Intervention is warranted and this can be achieved in many ways. The treatment option associated with the best outcomes is ablation directed with HRA, which can be performed in the office or in the operating room with minimal morbidity. This strategy is effective in patients with both low-volume and high-volume disease and is associated with a malignant progression rate of 0.4% in patients with treated HSIL.

Management of anal squamous intraepithelial lesions

Anal squamous intraepithelial lesions include both low-grade squamous intraepithelial lesions (LSIL) and high-grade squamous intraepithelial lesions (HSIL) and are caused by chronic infection with the human papillomavirus (HPV). The disease is increasing in both incidence and prevalence, especially among patients with the following risk factors: homosexual men, acquired or iatrogenic immunosuppression, and presence of other HPV-related diseases. Although the natural history of the disease is unknown, there is significant evidence that untreated HSIL progresses to squamous cell carcinoma in 11% of patients and in up to 50% of patients with extensive disease and immunosuppression. Anal cytology and reflex HPV DNA testing are used to screen for disease, particularly among patients with the aforementioned risk factors. Evaluation of the patient should include physical examination and high-resolution anoscopy (HRA) to evaluate for disease above and below the dentate line. Intervention is warranted and this can be achieved in many ways. The treatment option associated with the best outcomes is ablation directed with HRA, which can be performed in the office or in the operating room with minimal morbidity. This strategy is effective in patients with both low-volume and high-volume disease and is associated with a malignant progression rate of 0.4% in patients with treated HSIL.

Anal dysplasia screening: an evidence-based analysis

OBJECTIVE

This review considered the role of the anal Pap test as a screening test for anal dysplasia in patients at high risk of anal SCC. The screening process is now thought to be improved with the addition of testing for the human papillomavirus (HPV) in high-risk populations. High-resolution anoscopy (a method to view the rectal area, using an anoscope, a lighted instrument inserted into the rectum) rather than routine anoscopy-guided biopsy, is also now considered to be the diagnostic standard.

CLINICAL NEED

TARGET POPULATION AND CONDITION Anal cancer, like cervical cancer, is a member of a broader group of anogenital cancers known to be associated with sexually transmitted viral HPV infection. Human papillomavirus is extremely prevalent, particularly in young, sexually active populations. Sexual practices involving receptive anal intercourse lead to significantly elevated risk for anal dysplasia and cancer, particularly in those with immune dysfunctions. Anal cancer is rare. It occurs at a rate of about 1 to 2 per 100,000 in the general population. It is the least common of the lower gastrointestinal cancers, representing about 4% of them, in contrast to colorectal cancers, which remain the third most commonly diagnosed malignancy. Certain segments of the population, however, such as HIV-positive men and women, other chronic immune-suppressed patients (e.g., after a transplant), injection drug users, and women with genital dysplasia /cancer, have a high susceptibility to anal cancer. Those with the highest identified risk for anal cancer are HIV-positive homosexual and bisexual men, at a rate of 70 per 100,000 men. The risk for anal cancer is reported to be increasing dramatically in HIV-positive males and females, particularly since the introduction of highly active antiretroviral therapy in the mid-1990s. The introduction of effective viral therapy has been said to have transformed the AIDS epidemic in developed countries into a chronic disease state of long-term immunosuppression. In Ontario, there are about 25,000 people living with HIV infection; more than 6,000 of these are women. About 28% of the newly diagnosed HIV infections are in women, a doubling since 1999. It has also been estimated that 1 of 3 people living with HIV do no know it. HEALTH TECHNOLOGY DESCRIPTION: Anal Pap test screening involves the blind insertion of a swab into the anal canal and fixing cells either on a slide or in fluid for cytological examination. Anal cytology classified by the standardized Bethesda System is the same classification used for cervical cytology. It has 4 categories: normal, atypical squamous cells of uncertain significance, or squamous intraepithelial lesions which are further classified into low- or high-grade lesions. Abnormal cytological findings are subjected to further evaluations by high-resolution anoscopy, a technique similar to cervical colposcopy, and biopsy. Several HPV deoxyribonucleic acid detection technologies such as the Hybrid 11 Capture and the polymerase chain reaction are available to detect and differentiate HPV viral strains. Unlike cervical cancer, there are no universally accepted guidelines or standards of care for anal dysplasia. Moreover, there are no formal screening programs provincially, nationally, or internationally. The New York State Department of Health AIDS Institute has recently recommended (March 2007) annual anal pap testing in high-risk groups. In Ontario, reimbursement exists only for Pap tests for cervical cancer screening. That is, there is no reimbursement for anal Pap testing in men or women, and HPV screening tests for cervical or anal cancer are also not reimbursed.

METHODS

The scientific evidence base was evaluated through a systematic literature review. Assessments of current practices were obtained through consultations with various agencies and individuals including the Ministry of Health and Long-Term Care AIDS Bureau; Public Health Infectious Diseases Branch, Ministry of Health and Long-Term Care; Cancer Care Ontario; HIV/AIDS researchers; pathology experts; and HIV/AIDS clinical program directors. An Ontario-based budget impact was also done.

FINDINGS

No direct evidence was found for the existence of controlled studies evaluating the effectiveness of anal Pap test screening programs for impact on anal cancer morbidity or mortality. In addition, no studies were found on the use of HPV DNA testing in the screening or diagnostic setting for anal dysplasia. The reported prevalence of HPV infection in high-risk groups, particularly HIV-positive males, however, was sufficiently high to preclude any utility of HPV testing as an adjunct to anal Pap testing. Nine reports involving studies in the United States, United Kingdom, and Canada were identified that evaluated the performance characteristics of anal Pap test screening for anal dysplasia. All involved hospital-based specialty HIV/AIDS care clinics with mainly HIV-positive males. All studies involved experienced pathologists, so the results generally represent best-case scenarios. Estimates of anal Pap test sensitivity and specificity were highly variable, and depended on the varying prevalence of cytology abnormality and differential thresholds for abnormality for both cytology and histopathology. In the largest study of HIV-positive males, sensitivity varied from 46% (95% confidence interval [CI], 36%-56%) to 69% (95% CI, 60%-78%). Specificity ranged from 59% (95% CI, 53%-65%) to 81% (95% CI, 76%-85%). In the only study of HIV-negative males, sensitivity ranged from 26% (95% CI, 5%-47%) to 47% (95% CI, 26%-68%). Specificity ranged from 81% (95% CI, 76%-85%) to 92% (95% CI, 89%-95%). In comparison, cervical Pap testing has also been evaluated mainly in settings where there is a high prevalence of the disease, and estimates of sensitivitykij and specificity were also low and highly variable. In a systematic review involving cervical Pap testing, sensitivity ranged from 30% to 87% (mean, 47%) and specificity from 86% to 100% (mean, 95%).

CONCLUSIONS

No direct evidence exists to support the effectiveness of an anal Pap test screening program to reduce anal cancer mortality or morbidity. There are, however, strong parallels with cervical pap testing for cervical cancer. Sexually transmitted HPV viral infection is currently the acknowledged common causative agent for both anal and cervical cancer. Anal cancer rates in high-risk populations are approaching those of cervical cancer before the implementation of Pap testing. The anal Pap test, although it has been mainly evaluated only in HIV-positive males, has similar operating characteristics of sensitivity and specificity as the cervical Pap test. In general, the treatment options for precancer dysplasia in the cervix and the anus are similar, but treatment involving a definitive surgical resection in the anus is more limited because of the higher risk of complications. A range of ablative therapies has been applied for anal dysplasia, but evidence on treatment effectiveness, tolerability and durability, particularly in the HIV-positive patient, is limited.

Blind sampling is superior to anoscope guided sampling for screening for anal intraepithelial neoplasia

OBJECTIVES

Anal cytology smears are either collected "blind" (swab inserted 4 cm into anal canal and rotated) or guided through an anoscope (transformation zone visualised and then sampled). We compared these smear techniques with respect to sample quality and patient acceptability.

METHODS

Using a paired, random sequence clinical trial, 151 homosexual men (n = 95 HIV positive) underwent both smear techniques at a single visit; smear order was randomised and specimens were read blind. Both techniques utilised a Dacron swab, with water lubrication. Cytological specimens were prepared using a liquid based collection method (ThinPrep). The outcome measures were cytological specimen adequacy, cytological classification, presence of rectal columnar, squamous and metaplastic cells, contamination, patient comfort and acceptability, and volume of fluid that remained after the ThinPrep procedure.

RESULTS

Regardless of smear order, guided smears were less likely to detect higher grade abnormalities than blind smears (15 v 27 cases, p = 0.001). Controlling for smear order, guided smears were more likely to be assessed as "unsatisfactory" for cytological assessment (OR 6.93, 95% CI 1.92 to 24.94), and contain fewer squamous (OR 0.20, 95% CI 0.04 to 0.94) and metaplastic cells (OR 0.12, 95% CI 0.03 to 0.54) than blind smears; there were no other statistically significant differences between techniques. Regardless of smear technique, first performed smears were more likely to detect a higher grade abnormality than second performed smears (23 v eight cases, p < 0.001).

CONCLUSIONS

Blind cytology smears are superior to anoscope guided smears for screening for anal neoplasia in homosexual men.

The value of anal cytology and human papillomavirus typing in the detection of anal intraepithelial neoplasia: a review of cases from an anoscopy clinic

BACKGROUND

Previous studies have reached differing conclusions about the utility of anal cytology as a screening tool for anal intraepithelial neoplasia (AIN). There is a need also to establish whether HPV typing offers a useful adjunct to screening.

METHODS

We analysed data from 99 consecutive homosexual/bisexual male patients (89 HIV-1 positive) who underwent high resolution anoscopy. Follow up visits for these patients were also included, giving a total of 160 anoscopic procedures. Comparison was made between results of anal cytology using the sampling method of Palefsky, and histological findings of biopsies taken from abnormal areas seen on high resolution anoscopic examination of the anal canal. Swabs taken concurrently with the cytology were analysed for the presence of human papillomavirus (HPV) DNA and compared with the cytological and histological findings.

RESULTS

The sensitivity of the cytology was 83%, and the specificity 38% when compared with histology. At screening of 34 asymptomatic men, 83% had anal cytological dysplasia and 78% had AIN. There were no significant differences in the prevalence of hrHPV genotypes between different cytological or histological grades of abnormalities.

CONCLUSION

Anal cytology by the Palefsky method is simple to undertake, has a sensitivity and specificity comparable with cervical cytology, and can therefore be used as the basis of a pilot screening project in centres with large cohorts of HIV positive homosexual men who have a high risk of developing anal carcinoma. HPV genotyping is not a useful adjunct to cytological screening.

A study of anal intraepithelial neoplasia in HIV positive homosexual men

OBJECTIVES

To determine the prevalence of high grade anal intraepithelial neoplasia (HGAIN), the value of anal cytology in screening for HGAIN, and the characterisation of epidemiological factors and human papillomavirus (HPV) types.

METHODS

Prospective cohort study of HIV positive homosexual men. Subjects were interviewed, underwent STD, anal cytological, and HPV screening at enrolment and at subsequent follow up visits with anoscopy and biopsy at the final visit. 57 enrolled, average CD4 count 273 x 10(6)/l (10-588); 41 completed the cytological surveillance over the follow up period (181 visits, average follow up 17 months), 38 of these had anoscopy and anal biopsy.

RESULTS

Oncogenic HPV types were detected in 84% and high grade dyskaryosis in 10.5% (6/57) at enrollment. There was a 70% incidence of high grade dyskaryosis during follow up in patients with negative/warty or low grade dyskaryosis at enrollment. Anoscopy correlated with histology in high grade AIN lesions (sensitivity 91%, specificity 54%) and cytology was 78% sensitive (18/23) for HGAIN on biopsy.

CONCLUSIONS

AIN and infection with multiple oncogenic HPV types are very common among immunosuppressed HIV positive homosexual men. Apparent progression from low to high grade cytological changes occurred over a short follow up period, with no cases of carcinoma. All 23 cases of HGAIN were predicted by cytology and/or anoscopy. Future studies focusing on the risk of progression to carcinoma are needed before applying anal cytology as a screening tool for AIN in this population.