Cytology in Anal Cancer Screening: Practical Review for Clinicians

Anal carcinoma - exploring the epidemiology, risk factors, pathophysiology, diagnosis, and treatment

Anal carcinoma is a relatively rare tumor that accounts for approximately 2% of gastrointestinal malignancies and less than 7% of anorectal cancers. Most anal tumors originate between the anorectal junction and the anal verge. Risk factors for the disease include human papillomavirus infection, human immunodeficiency virus, tobacco use, immunosuppression, female sex, and older age. The pathogenesis of anal carcinoma is believed to be linked to human papillomavirus-related inflammation, leading to dysplasia and progression to cancer. Squamous cell carcinoma is the most common type of anal tumor, with an annual incidence of approximately 1 to 2 per 100000 persons. Treatment regarding anal cancer has emerged over time. However, chemoradiation therapy remains the mainstay approach for early localized disease. Patients with metastatic disease are treated with systemic therapy, and salvage surgery is reserved for disease recurrence following chemoradiation. This article aims to provide background information on the epidemiology, risk factors, pathology, diagnosis, and current trends in the management of anal cancer. Future directions are briefly discussed.

Self-collected versus clinician-collected anal swabs for anal cancer screening: A systematic review and meta-analysis

Anal squamous cell carcinoma (ASCC) incidence is increasing globally. International consensus guidelines published in 2024 include HPV and/or cytology testing of anal swabs in those at greatest risk of ASCC. Self-collected anal swabs may be important for increasing screening uptake, but evidence is needed as to their equivalence to clinician-collected swabs. We searched Medline, Embase, Cochrane Library, and CINAHL databases for publications to 13 June 2023. Studies were included if reporting data on HPV testing, cytology testing, or acceptability, for both self- and clinician-collected anal swabs. Risk of bias was assessed using the QUADAS-2 assessment tool. The primary outcome was HPV and cytology sampling adequacy. Secondary outcomes were HPV and cytology results, and acceptability of collection methods. Thirteen papers describing 10 studies were eligible. Sample adequacy was comparable between self- and clinician-collected swabs for HPV testing (meta-adequacy ratio: 1.01 [95% CI 0.97-1.05]) but slightly lower for cytology by self-collection (meta-adequacy ratio: 0.91 [95% CI 0.88-0.95]). There was no significant difference in prevalence (meta-prevalence ratio: 0.83 (95% CI 0.65-1.07) for any HR-HPV, 0.98 (95% CI 0.84-1.14) for any HPV, and 0.68 (95% CI 0.33-1.37) for HPV16), or any cytological abnormality (meta-prevalence ratio 1.01 [95% CI 0.86-1.18]). Only three papers reported acceptability results. Findings indicate self-collection gives equivalent sample adequacy for HPV testing and ~ 10% inferior adequacy for cytological testing. Meta-prevalence was similar for HPV and cytology, but confidence intervals were wide. Larger studies are required to definitively assess use of self-collected swabs in anal cancer screening programs, including acceptability.

Perianal disease in inflammatory bowel disease: Broadening treatment and surveillance strategies for anal cancer

The perianal disease affects up to one-third of individuals with Crohn's disease (CD), causing disabling symptoms and significant impairment in quality of life, particularly for those with perianal fistulising CD (PFCD). The collaborative effort between gastroenterologists and surgeons is essential for addressing PFCD to achieve fistula closure and promote luminal healing. Limited fistula healing rates with conventional therapies have prompted the emergence of new biological agents, endoscopic procedures and surgical techniques that show promising results. Among these, mesenchymal stem cells injection is a particularly hopeful therapy. In addition to the burden of fistulas, individuals with perianal CD may face an increased risk of developing anal cancer. This underscores the importance of surveillance programmes and timely interventions to prevent late diagnoses and poor outcomes. Currently, there is no established formal anal screening programme. In this review, we provide an overview of the current state of the art in managing PFCD, including novel medical, endoscopic and surgical approaches. The discussion also focuses on the relevance of establishing an anal cancer screening programme in CD, intending to propose a risk-based surveillance algorithm. The validation of this surveillance programme would be a significant step forward in improving patient care and outcomes.

Cumulative Detection of Anal High-Grade Squamous Intraepithelial Lesions Over 2-Year Follow-up in Men Who Have Sex With Men Living With Human Immunodeficiency Virus in France

We assessed cumulative detection and determinants of anal high-grade squamous intraepithelial lesions (HSILs) in men who have sex with men living with human immunodeficiency virus and who underwent 3 visits over 2 years, with cytology and high-resolution anoscopy, within the ANRS-EP57-APACHES study. The cumulative HSIL detection rate was 33% (134 of 410), of which 48% HSILs were detected at baseline. HSIL detection varied considerably by center (from 13% to 51%). The strongest HSIL determinants were baseline human papillomavirus 16 (adjusted odds ratio, 8.2; 95% confidence interval, 3.6-18.9) and p16/Ki67 (4.6 [2.3-9.1]). Repeated annual cytology and high-resolution anoscopy improved HSIL detection but did not fully compensate for between-center heterogeneity.

A comprehensive review of anal cancer-with a special focus on anal cytology

The diagnosis of anal cancer is relatively uncommon, but its incidence has been steadily increasing in high-risk populations. In the 2001 Bethesda System for Reporting Cervical Cytology, anal cytology was introduced as a component. Since then, it has been recognized as a potential tool for screening anal cancer, often in conjunction with high-resolution anoscopy. There are notable similarities between anal cancer and cervical cancer, including the causative role of human papillomavirus. However, there are also significant differences, particularly in terms of disease prevalence. Anal cytology may be used as a primary screening test, and in the event of abnormalities, patients are subsequently directed for high-resolution anoscopy. However, the best approach for anal cancer screening is yet to be determined and uniformly implemented. This comprehensive review article provides an in-depth analysis of the epidemiology and incidence of anal precursor and malignant lesions. It explores the various methods of sample procurement, preparation, interpretation (including sensitivity and specificity), and reporting terminology in anal cytology. The article also addresses the significance of concurrent high-risk human papillomavirus screening in anal cytology and its role in screening programs. Furthermore, it discusses the follow-up, prevention, and subsequent management strategies for anal cancers. By synthesizing current knowledge in these areas, this review aims to provide a comprehensive understanding of anal cytology and its implications in the early detection, prevention, and management of anal neoplasia and cancer.

A case of a rare type of cancer: Anal squamous cell carcinoma in a patient without significant risk factors

INTRODUCTION

Anal carcinoma is a relatively uncommon tumor that accounts for less than 2% of large bowel malignancies and approximately 1-6% of anorectal tumors. Most anal cancers originate in the mucosa between the anorectal junction and the anal verge. Risk factors for anal carcinoma include human papillomavirus (HPV), immunosuppression, older age, female gender, and smoking. Approximately 85% of anal cancers are squamous cell carcinoma, and the pathophysiology is believed to be linked to HPV-related inflammation, leading to dysplasia and progression to cancer.

CASE PRESENTATION

We present the case of a 65-year-old woman who sought medical attention at the emergency department (ED) due to rectal pain and concurrent rectal lesions persisting for the past three months. Before admission, she reported abdominal discomfort and constipation for 2-3 months, during which she took laxatives for relief. Laboratory findings in the ED were significant for anemia and leukocytosis, with all other values within normal limits. Blood tests, including antibodies for HPV and human immunodeficiency virus, were negative. A computed tomography scan of the abdomen and pelvis was largely unremarkable. On physical examination, perianal lesions with heaped-up edges were observed. A punch biopsy was subsequently performed, revealing squamous cell carcinoma (SCC). About three weeks following discharge, after one week of admission to the general medicine ward, the patient started chemoradiation therapy and reported some improvement in her symptoms. Seven weeks later, she was in remission.

DISCUSSION

Squamous cell carcinoma (SCC) of the anus, a rare disease entity, is often a slow and progressive malignancy. The length of time for patients to become symptomatic, in combination with its mimicking clinical presentation to common gastrointestinal tract diseases and its rarity, makes diagnosis challenging. Additionally, a patient lacking traditional risk factors for anal cancer, such as HPV and smoking, may further complicate diagnosis, treatment, and quality of life.

CONCLUSION

This case report emphasizes the pathogenesis and the similarities in clinical presentation of anal cancer to mild diseases, which may lead to a delay in diagnosis. Patients with anal carcinoma often delay seeking medical care, which is anecdotal in relation to the considerable overlap in symptoms of benign diseases such as hemorrhoids. Therefore, patients with "hemorrhoid" complaints, rectal bleeding, or rectal mass should warrant further physical examination and prompt referral to a gastroenterologist or a colorectal surgeon for additional evaluation.

Epidemiology of human papillomavirus-associated anogenital cancers in Granada: a three-decade population-based study

Introduction

HPV infection is a common risk factor for all anogenital cancers. However, there are important differences in the epidemiology of anogenital cancers and these have not been compared considering diverse epidemiological indicators over a long period of time. To fill this gap, we investigated incidence, mortality, and survival trends of anogenital cancers over a period of three decades.

Methods

We conducted an observational registry-based study using data from the population-based cancer registry of Granada in southern Spain. We collected data on all incident cases of anogenital cancer (cervical, anal, penile, vulvar, and vaginal cancer) diagnosed between 1985 and 2017. We calculated crude and age-standardized incidence and mortality rates, and 1, 3, and 5-year overall and net survival. We further conducted time-trend analysis calculating annual percent changes (APC) for each cancer site.

Results

The incidence of anogenital cancers decreased slightly during the past 30 years, with the exception of vulvar cancer, where a slight increase was observed. Mortality decreased significantly for cervical cancer over the study period but increased non-significantly for the remaining cancer sites. Survival rates were similar to those reported in comparable countries and increased for cervical and vulvar cancer.

Discussion

Cervical cancer was the greatest contributor to the burden of anogenital cancers and showed a marked improvement in all indicators in comparison to the remaining cancer sites.

Anal High-risk Human Papillomavirus Infection, Squamous Intraepithelial Lesions, and Anal Cancer in Patients with Inflammatory Bowel Disease: A Systematic Review and Meta-analysis

BACKGROUND

Ulcerative colitis [UC] and Crohn's disease [CD] can be associated with severe comorbidities, namely opportunistic infections and malignancies. We present the first systematic review and meta-analysis evaluating the burden of anal human papillomavirus disease in patients with UC and CD.

METHODS

PubMed, Web of Science, and Scopus were searched until November 2022. Meta-analyses were performed using random effects models. The protocol was recorded at PROSPERO register with the number CRD42022356728.

RESULTS

Six studies, including 78 711 patients with UC with a total follow-up of 518 969 person-years, described the anal cancer incidence rate. For anal cancer incidence rate in CD, six studies were selected, including 56 845 patients with a total follow-up of 671 899 person-years. The incidence of anal cancer was 10.2 [95% CI 4.3 - 23.7] per 100 000 person-years in UC and 7.7 [3.5 - 17.1] per 100 000 person-years in CD. A subgroup analysis of anal cancer in perianal CD, including 7105 patients, was calculated with incidence of 19.6 [12.2 - 31.6] per 100 000 person-years [three studies included]. Few studies described prevalence of anal cytological abnormalities [four studies including 349 patients] or high-risk human papillomavirus [three studies including 210 patients], with high heterogeneity. Prevalence of cytological abnormalities or high-risk human papillomavirus was not associated with pharmacological immunosuppression in the studies included.

CONCLUSION

The incidence of anal cancer is higher in UC than in CD, with the exception of perianal CD. There are limited and heterogeneous data on anal high-risk human papillomavirus infection and squamous intraepithelial lesions prevalence in this population.

Anal Cancer in High-Risk Women: The Lost Tribe

In developed countries the incidence of anal squamous cell carcinoma (SCC) has been rising; especially in women over the age of 60 years who present with more advanced disease stage than men. Historically, anal SCC screening has focused on people living with Human Immunodeficiency Virus (HIV) (PLWH) who are considered to be at the highest risk of anal SCC, and its precancerous lesion, anal squamous intraepithelial lesion (SIL). Despite this, women with vulval high-grade squamous epithelial lesions (HSIL) and SCCs have been shown to be as affected by anal HSIL and SCC as some PLWH. Nevertheless, there are no guidelines for the management of anal HSIL in this patient group. The ANCHOR trial demonstrated that treating anal HSIL significantly reduces the risk of anal SCC in PLWH, there is therefore an unmet requirement to clarify whether the screening and treatment of HSIL in women with a prior genital HSIL is also beneficial. This review presents the current evidence supporting the screening, treatment, and surveillance of anal HSIL in high-risk women with a previous history of genital HSIL and/or SCC.

Human papillomavirus-related cancer risk for solid organ transplant recipients during adult life and early prevention strategies during childhood and adolescence

Malignancies are among the top three causes of patient death in pediatric and adult kidney transplant (KT) recipients. Solid organ transplant (SOT) recipients, including KT individuals, experience more cancer compared with the general population, including human papillomavirus (HPV)-related anogenital and oropharyngeal cancers. This article describes the epidemiology, pathophysiology and natural history of the HPV infection in both the general population and in SOT recipients, as well as its role in the development of HPV-related pre-cancerous lesions and cancers. Emphasis is given to the primary prevention strategy, HPV vaccination in SOT recipients, and its particularities compared with the general population. Secondary prevention strategies in SOT recipients are discussed and compared with the general population, highlighting cervical cancer screening needs within SOT populations. The article emphasizes how these primary and secondary HPV prevention strategies applied during childhood and adolescence by the pediatric transplant professionals, can lower the burden of HPV-related cancers for SOT recipients in subsequent years, during their adult life.

Proteases and HPV-Induced Carcinogenesis

Simple Summary

Human papillomavirus (HPV) infection is a sexually transmitted disease with high prevalence worldwide. Although most HPV infections do not lead to cancer, some HPV types are correlated with the majority of cervical cancers, and with some anogenital and oropharyngeal cancers. Moreover, enzymes known as proteases play an essential role in the pathogenic process in HPV-induced carcinogenesis. This review highlights the role of proteases and recent epidemiological data regarding HPV-dependent carcinogenesis.

Abstract

Persistent infection with Human papillomavirus (HPV) is the main etiologic factor for pre-malignant and malignant cervical lesions. Moreover, HPV is also associated with oropharynx and other anogenital carcinomas. Cancer-causing HPV viruses classified as group 1 carcinogens include 12 HPV types, with HPV 16 and 18 being the most prevalent. High-risk HPVs express two oncoproteins, E6 and E7, the products of which are responsible for the inhibition of p53 and pRB proteins, respectively, in human keratinocytes and cellular immortalization. p53 and pRB are pleiotropic proteins that regulate the activity of several signaling pathways and gene expression. Among the important factors that are augmented in HPV-mediated carcinogenesis, proteases not only control processes involved in cellular carcinogenesis but also control the microenvironment. For instance, genetic polymorphisms of matrix metalloproteinase 1 (MMP-1) are associated with carcinoma invasiveness. Similarly, the serine protease inhibitors hepatocyte growth factor activator inhibitor-1 (HAI-1) and -2 (HAI-2) have been identified as prognostic markers for HPV-dependent cervical carcinomas. This review highlights the most crucial mechanisms involved in HPV-dependent carcinogenesis, and includes a section on the proteolytic cascades that are important for the progression of this disease and their impact on patient health, treatment, and survival.

Human papillomavirus 16 L1 gene methylation as a potential biomarker for predicting anal intraepithelial neoplasia in men who have sex with men (MSM)

The human papillomavirus (HPV) 16 early promoter and L1 gene methylation were quantitatively measured using pyrosequencing assay in anal cells collected from men who have sex with men (MSM) to determine potential biomarkers for HPV-related anal cancer. The methylation patterns of HPV16 genes, including the early promoter (CpG 31, 37, 43, 52, and 58) and L1 genes (CpG 5600, 5606, 5609, 5615, 7136, and 7145), were analyzed in 178 anal samples. The samples were diagnosed as normal, anal intraepithelial neoplasia (AIN) 1, AIN2, and AIN3. Low methylation levels of the early promoter (< 10%) and L1 genes (< 20%) were found in all detected normal anal cells. In comparison, medium to high methylation (≥ 20–60%) in the early promoter was found in 1.5% (1/67) and 5% (2/40) of AIN1 and AIN2-3 samples, respectively. Interestingly, slightly increased L1 gene methylation levels (≥ 20–60%), especially at the HPV16 5’L1 regions CpGs 5600 and 5609, were demonstrated in AIN2-3 specimen. Moreover, a negative correlation between high HPV16 L1 gene methylation at CpGs 5600, 5609, 5615, and 7145 and a percentual CD4 count was found in AIN3 HIV positive cases. When comparing the methylation status of AIN2-3 to that of normal/AIN1 lesions, the results indicated the potential of using HPV16 L1 gene methylation as a biomarker for HPV-related cancer screening.

Prevention and Screening of HPV Malignancies

It is estimated that 5% of the global cancer burden, or approximately 690,000 cancer cases annually, is attributable to human papillomavirus (HPV). Primary prevention through prophylactic vaccination is the best option for reducing the burden of HPV-related cancers. Most high-income countries (HICs) have introduced the HPV vaccine and are routinely vaccinating adolescent boys and girls. Unfortunately, although they suffer the greatest morbidity and mortality due to HPV-related cancers, many lower- and middle-income countries (LMICs) have been unable to initiate and sustain vaccination programs. Secondary prevention in the form of screening has led to substantial declines in cervical cancer incidence in areas with established screening programs, but LMICs with absent or inadequate screening programs have high incidence rates. Meanwhile, HICs have seen incidence rates of anal and oropharyngeal cancers rise owing to the limited availability of organized screening for anal cancer and no validated screening options for oropharyngeal cancer. The implementation of screening programs for individuals at high risk of these cancers has the potential to reduce the burden of cervical cancer in LMICs, of anal and oropharyngeal cancers in HICs, and of anal cancer for highly selected HIV+ populations in LMICs. This review will discuss primary prevention of HPV-related cancers through vaccination and secondary prevention through screening of cervical, anal, and oropharyngeal cancers. Areas of concern and highlights of successes already achieved are included.

Anal cancer and precancerous lesions: a call for improvement

Anal squamous cell carcinoma is the most common type of anal cancer and is largely associated with anal human papillomavirus infection. The incidence of anal squamous cell carcinoma is increasing, and although still uncommon in the general population, a high incidence has been noted in specific population groups (eg, patients with HIV, men who have sex with men [MSM], recipients of solid organ transplants, women with genital neoplasia, and patients with systemic lupus erythematosus or inflammatory bowel disease). The higher incidence among individuals who are HIV-positive makes anal squamous cell carcinoma one of the most common non-AIDS-defining cancers among HIV-positive individuals. Anal cancer screening in high-risk groups aims to detect high-grade squamous intraepithelial lesions, which are considered anal precancerous lesions, and for which identification can provide an opportunity for prevention. A blind anal cytology is normally the first screening method, and for patients with abnormal results, this approach can be followed by an examination of the anal canal and perianal area under magnification, along with staining-a technique known as high-resolution anoscopy. Digital anorectal examination can enable early anal cancer detection. Several societies are in favour of screening for HIV-positive MSM and recipients of transplants. There are no current recommendations for screening of anal precancerous lesions via endoscopy, but in high-risk groups, a careful observation of the squamocolumnar junction should be attempted. Several treatments can be used to treat high-grade squamous intraepithelial lesions, including argon plasma coagulation or radiofrequency ablation, which are largely limited by high recurrence rates. Gastroenterologists need to be aware of anal squamous cell carcinoma and anal precancerous lesions, given that patients at high risk are frequently encountered in the gastroenterology department. We summarise simple procedures that can help in early anal squamous cell carcinoma detection.

Screening Women for Anal Cancers: Guidance for Health Care Professionals

Anal cancer is rare in the general population but is steadily increasing in incidence over the past decade especially in women. Identification and screening of women with high risk facilitates detection of anal precancer and early-stage cancer, improves survival, and potentially uses less invasive therapies compared with the conventional chemoradiation treatments used for advanced cancers. No recently published guidelines currently describe details about screening women for anal squamous cell cancer (ASCC). The available evidence supports the existence of groups of women with higher prevalence of ASCC (e.g., women with human immunodeficiency virus, immune suppression, or previous lower-genital high-grade lesion or cancer) who would likely benefit from screening with some combination of anal cytology and human papillomavirus testing. Additional research is needed to establish the cost-effectiveness and the influence of screening on ASCC mortality rates.

Recommendations Favoring Anal Cytology as a Method for Anal Cancer Screening: A Systematic Review

Clinicians are increasingly facing the decision of performing anal cancer screening in high-risk groups. Anal cytology is commonly the first approach. We systematically reviewed recommendations favoring anal cytology for anal cancer screening. Three databases were searched: PubMed, Scopus, and Embase, from January 2007 to 12 September 2019. The references cited by the retrieved articles and the websites of relevant organizations were also searched without language restrictions. Studies reporting guidelines from regional or national societies, institutes, or groups were included. Eight papers met the inclusion criteria and were selected, five were from the United States of America (USA) and three from Europe. There were no national recommendations published. There was one guideline specifically for solid-organ transplant recipients. The other seven targeted HIV-positive patients, with HIV-positive men who have sex with men (MSM) included as a screening group in all of these. Two recommendations favored screening in all HIV-positive patients. Five recommendations targeting HIV-positive patients made considerations about the cytology follow-up, recommending at least annual cytology in case of a normal result, and in case of squamous cytological abnormalities, a referral for anoscopy/high-resolution anoscopy. There were no recommendations for upper and lower age limits for screening. In conclusion, several societies recommend anal cancer screening using anal cytology in HIV-positive MSM patients. There is a lack of screening recommendations for other high-risk groups, with only one society recommending screening in transplant recipients.