Search

OBJECTIVES: Anal cancer risk is elevated in MSM with HIV (MSMWH). Anal high-risk human papillomavirus (hr-HPV) infection is necessary but insufficient to develop high-grade squamous intraepithelial lesion (HSIL), the anal cancer precursor, suggesting additional factors. We sought to determine whether the microbiome of the anal canal is distinct by comparing it with the microbiome of stool. We also sought to determine whether changes in the anal microbiome are associated with HSIL among MSMWH. DESIGN: Cross-sectional comparison of the microbiome of the anal canal with the microbiome of stool in MSMWH and cross-sectional comparison of the anal microbiome of MSMWH with anal HSIL with the anal microbiome of MSMWH without anal HSIL. METHODS: Sterile swabs were used to sample the anus of MSMWH for microbiome and HPV testing, followed by high-resolution anoscopy. Stool samples were mailed from home. 16S sequencing was used for bacterial identification. Measures of alpha diversity, beta diversity, and differential abundance analysis were used to compare samples. RESULTS: One hundred sixty-six anal samples and 103 matching stool samples were sequenced. Beta diversity showed clustering of stool and anal samples. Of hr-HPV-positive MSMWH, 31 had HSIL and 13 had no SIL. Comparison of the microbiome between these revealed 28 different species. The highest-fold enrichment among MSMWH/hr-HPV/HSIL included pro-inflammatory and carcinogenic Prevotella, Parasuterella, Hungatella, Sneathia, and Fusobacterium species. The anti-inflammatory Anaerostipes caccae showed the greatest reduction among MSMWH/hr-HPV/HSIL. CONCLUSION: The anal microbiome is distinct from stool. A pro-inflammatory and carcinogenic environment may be associated with anal HSIL.

BACKGROUND: Anal intraepithelial neoplasia grade III is a precursor to squamous cell carcinoma of the anus for which rates are nearly 20-fold higher in people with HIV than in the general population in the United States. We describe trends in anal intraepithelial neoplasia grade III diagnosis and risk of squamous cell carcinoma of the anus following anal intraepithelial neoplasia grade III by HIV status and sex. METHODS: We used data from a population-based linkage between cancer and HIV registries in 11 US states; Puerto Rico; and Washington, DC, during 1996-2019. We identified all individuals with a diagnosis of anal intraepithelial neoplasia grade III and determined their HIV status. We estimated the average annual percentage change of anal intraepithelial neoplasia grade III using Poisson regression stratified by HIV status and sex. We estimated the 5-year cumulative incidence of squamous cell carcinoma of the anus following an anal intraepithelial neoplasia grade III diagnosis stratified by sex, HIV status, and prior AIDS diagnosis. RESULTS: Among people with HIV, average annual percentage changes for anal intraepithelial neoplasia grade III were 15% (95% confidence interval [CI] = 12% to 17%) per year among females and 12% (95% CI = 11% to 14%) among males. Average annual percentage changes for those without HIV were 8% (95% CI = 7% to 8%) for females and 8% (95% CI = 6% to 9%) for males. Among people with HIV, a prior AIDS diagnosis was associated with a 2.7-fold (95% CI = 2.23 to 3.40) and 1.9-fold (95% CI = 1.72 to 2.02) increased risk of anal intraepithelial neoplasia grade III diagnosis for females and males, respectively. Five-year cumulative incidence of squamous cell carcinoma of the anus following anal intraepithelial neoplasia grade III for people with HIV with a prior AIDS diagnosis were 3.4% and 3.7% for females and males, respectively. CONCLUSIONS: Rates of anal intraepithelial neoplasia grade III diagnoses have increased since 1996, particularly for people with HIV, likely influenced by increased screening. A prior AIDS diagnosis was strongly associated with risk of anal intraepithelial neoplasia grade III diagnosis.

The role and method of image-based staging of anal cancer has evolved with the rapid development of newer imaging modalities and the need to address the rising incidence of this rare cancer. In 2014, the European Society of Medical Oncology mandated pelvic magnetic resonance imaging (MRI) for anal cancer and subsequently other societies such as the National Comprehensive Cancer Network followed suit with similar recommendations. Nevertheless, great variability exists from center to center and even within individual centers. Notably, this is in stark contrast to the imaging of the anatomically nearby rectal cancer. As participating team members for this malignancy, we embarked on a comprehensive literature review of anal cancer imaging to understand the relative merits of these new technologies which developed after computed tomography (CT), e.g., MRI and positron emission tomography/computed tomography (PET/CT). The results of this literature review helped to inform our next stage: questionnaire development regarding the imaging of anal cancer. Next, we distributed the questionnaire to members of the Society of Abdominal Radiology (SAR) Rectal and Anal Disease-Focused Panel, a group of abdominal radiologists with special interest, experience, and expertise in rectal and anal cancer, to provide expert radiologist opinion on the appropriate anal cancer imaging strategy. In our expert opinion survey, experts advocated the use of MRI in general (65% overall and 91-100% for primary staging clinical scenarios) and acknowledged the superiority of PET/CT for nodal assessment (52-56% agreement for using PET/CT in primary staging clinical scenarios compared to 30% for using MRI). We therefore support the use of MRI and PET and suggest further exploration of PET/MRI as an optimal combined evaluation. Our questionnaire responses emphasized the heterogeneity in imaging practice as performed at numerous academic cancer centers across the United States and underscore the need for further reconciliation and establishment of best imaging practice guidelines for optimized patient care in anal cancer.

The Society of Abdominal Radiologys Colorectal and Anal Cancer Disease-Focused Panel (DFP) first published a rectal cancer lexicon paper in 2019. Since that time, the DFP has published revised initial staging and restaging reporting templates, and a new SAR user guide to accompany the rectal MRI synoptic report (primary staging). This lexicon update summarizes interval developments, while conforming to the original lexicon 2019 format. Emphasis is placed on primary staging, treatment response, anatomic terminology, nodal staging, and the utility of specific sequences in the MRI protocol. A discussion of primary tumor staging reviews updates on tumor morphology and its clinical significance, T1 and T3 subclassifications and their clinical implications, T4a and T4b imaging findings/definitions, terminology updates on the use of MRF over CRM, and the conundrum of the external sphincter. A parallel section on treatment response reviews the clinical significance of near-complete response and introduces the lexicon of regrowth versus recurrence. A review of relevant anatomy incorporates updated definitions and expert consensus of anatomic landmarks, including the NCCNs new definition of rectal upper margin and sigmoid take-off. A detailed review of nodal staging is also included, with attention to tumor location relative to the dentate line and locoregional lymph node designation, a new suggested size threshold for lateral lymph nodes and their indications for use, and imaging criteria used to differentiate tumor deposits from lymph nodes. Finally, new treatment terminologies such as organ preservation, TNT, TAMIS and watch-and-wait management are introduced. This 2023 version aims to serve as a concise set of up-to-date recommendations for radiologists, and discusses terminology, classification systems, MRI and clinical staging, and the evolving concepts in diagnosis and treatment of rectal cancer.