Cancer of the Anal Canal: Diagnosis, Staging and Follow-Up with MRI

Current update on the role of endoanal ultrasound: a primer for radiologists

Endoanal ultrasound (EAUS) is a valuable imaging modality for the evaluation of anal and perianal pathologies. It provides detailed information about the anatomy and physiology of the anorectal region and has been used in pre-and post-operative settings of anorectal pathologies. EAUS is not only useful in the evaluation of benign pathologies but also in loco-regional staging of anal and rectal tumors. EAUS has several advantages over MRI, including reduced cost, better patient tolerance, and improved scope of application in patients with contraindications to MRI. Despite its benefits, EAUS is not widely performed in many centers across the globe. This article aims to educate radiologists, trainees, and surgeons about the indications, contraindications, patient preparation, imaging technique, and findings of EAUS. We will also highlight the technical difficulties, diagnostic challenges, and procedural complications encountered during EAUS, along with a comparative analysis of EAUS with other imaging approaches.

Accuracy and Clinical Impact of Persistent Disease Diagnosed on Diffusion-Weighted Imaging and Accuracy of Pelvic Nodal Assessment on Magnetic Resonance Imaging for Squamous Cell Carcinoma of the Anus in the 6-Month Interval Post Chemoradiotherapy

PURPOSE

To evaluate the diagnostic performance of diffusion-weighted imaging (DWI) in the 6-month interval post chemoradiation therapy (CRT) in determining persistent disease and whether persistent diffusion restriction on DWI at 6 months is associated with overall survival; and secondarily, to investigate the accuracy of pelvic lymph node assessment on T2-weighted imaging and DWI in the 6-month interval post CRT, in patients with squamous cell carcinoma of the anus.

METHODS AND MATERIALS

This retrospective study included patients with squamous cell carcinoma of the anus who underwent CRT followed by restaging rectal MRI from January 2010 to April 2020, with ≥1 year of follow-up after CRT. DW images were qualitatively evaluated by 2 junior and 2 senior abdominal radiologists to determine anal persistent disease. The reference standard for anal persistent disease was digital rectal examination/endoscopy and histopathology. Diagnostic performance was estimated using sensitivity, specificity, negative predictive value, and positive predictive value. Survival outcomes were evaluated via Kaplan-Meier analysis, and associations between survival outcomes and DWI status were tested for significance using the log-rank test. Additionally, DW and T2-weighted images were evaluated to determine lymph node status.

RESULTS

Among 84 patients (mean age, 63 ± 10.2 years; 64/84 [76%] female), 14 of 84 (17%) had confirmed persistent disease. Interreader agreement on DWI between all 4 radiologists was moderate (Light's κ = 0.553). Overall, DWI had a sensitivity of 71.4%, specificity of 72.1%, positive predictive value of 34.5%, and negative predictive value of 92.5%. Patients with a negative DWI showed better survival than patients with a positive DWI (3-year overall survival of 92% vs 79% and 5-year overall survival of 87% vs 74%), although the difference did not reach statistical significance (P = .063). All patients with suspicious lymph nodes (14/14, 100%) showed negative pathology or decreased size during follow-up.

CONCLUSIONS

At 6 months post CRT, DWI showed value in excluding anal persistent disease. Persistent diffusion restriction on DWI was not significantly associated with overall survival. Pelvic nodal assessment on DWI and T2-weighted imaging was limited in predicting persistent nodal metastases.

Low Rectal Cancers at Initial Staging MRI

Low rectal cancers, which are associated with increased risk of local recurrent disease and poorer prognosis, have unique anatomic considerations and issues for staging and treatment that do not apply to mid and high rectal cancers. Although tumor histology help drive the staging and treatment of all rectal cancers, it is of particular importance in low rectal cancers, which may involve the anal canal, to help establish whether a low rectal mass should be staged and treated as a rectal cancer (ie, adenocarcinoma) or an anal cancer (ie, squamous cell carcinoma). Optimal staging and treatment of rectal cancer are contingent on tumor location and local extent, which help guide management decisions including neoadjuvant therapy and curative surgical treatment strategies. Tumor location in the low rectum and local involvement of the anal canal, sphincter, and pelvic floor help determine whether a patient can undergo sphincter-preserving resection such as a low anterior resection versus abdominoperineal resection to achieve negative surgical margins. Issues exist related to the anatomy and patterns of disease spread that are unique to the low rectum and include how to determine and stage anal sphincter involvement, mesorectal fascia status at the pelvic floor, and nodal status of extramesorectal nodes such as the external iliac and inguinal lymph nodes. For these reasons, it is imperative that radiologists who interpret rectal cancer staging MRI examinations feel comfortable with the unique anatomy of the low rectum and anal canal, nuances of low rectal cancer local disease spread, and treatment paradigms for low rectal cancer. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center. See the invited commentary by Gollub in this issue.

An Updated Review on Imaging and Staging of Anal Cancer-Not Just Rectal Cancer

Anal cancer is a rare disease, but its incidence has been increasing steadily. Primary staging and assessment after chemoradiation therapy are commonly performed using MRI, which is considered to be the preferred imaging modality. CT and PET/CT are useful in evaluating lymph node metastases and distant metastatic disease. Anal squamous-cell carcinoma (ASCC) and rectal adenocarcinoma are typically indistinguishable on MRI, and a biopsy prior to imaging is necessary to accurately stage the tumor and determine the treatment approach. This review discusses the histology, MR technique, diagnosis, staging, and treatment of anal cancer, with a particular focus on the differences in TNM staging between anal and rectal carcinomas.

PURPOSE

This review discusses the histology, MR technique, diagnosis, staging, and treatment of anal cancer, with a particular focus on the differences in TNM staging between anal squamous-cell carcinoma (ASCC) and rectal adenocarcinoma.

METHODS AND MATERIALS

To conduct this updated review, a comprehensive literature search was performed using prominent medical databases, including PubMed and Embase. The search was limited to articles published within the last 10 years (2013-2023) to ensure their relevance to the current state of knowledge.

INCLUSION CRITERIA

(1) articles that provided substantial information on the diagnostic techniques used for ASCC, mainly focusing on imaging, were included; (2) studies reporting on emerging technologies; (3) English-language articles.

EXCLUSION CRITERIA

articles that did not meet the inclusion criteria, case reports, or articles with insufficient data. The primary outcome of this review is to assess the accuracy and efficacy of different diagnostic modalities, including CT, MRI, and PET, in diagnosing ASCC. The secondary outcomes are as follows: (1) to identify any advancements or innovations in diagnostic techniques for ASCC over the past decade; (2) to highlight the challenges and limitations of the diagnostic process.

RESULTS

ASCC is a rare disease; however, its incidence has been steadily increasing. Primary staging and assessment after chemoradiation therapy are commonly performed using MRI, which is considered to be the preferred imaging modality. CT and PET/CT are useful in evaluating lymph node metastases and distant metastatic disease.

CONCLUSION

ASCC and rectal adenocarcinoma are the most common histological subtypes and are typically indistinguishable on MRI; therefore, a biopsy prior to imaging is necessary to stage the tumor accurately and determine the treatment approach.

Anal Cancer: The Past, Present and Future

Anal cancer is a rare cancer that accounts for about 2% of all gastrointestinal tract malignancies. Among anal cancer, squamous cell cancer is the most common malignancy. The incidence of all stages of anal squamous cell cancer has been increasing. Human papillomavirus infection and immunosuppression are major risk factors for anal cancer. The management of anal cancer has evolved over the past several decades and continues to do so. Chemoradiation therapy remains the mainstay for treatment for most patients with early-stage disease, whereas systemic therapy is the primary treatment for patients with metastatic disease. Patients with persistent disease or recurrence following chemoradiation therapy are treated with salvage surgery. Access to novel cytotoxic combinations and immunotherapy has improved the outcomes of patients with advanced disease. This review provides an overview of advances in the management of anal cancer over the past two decades. This paper reviews the epidemiology, risk factors, pathology, diagnosis, and management of localized and advanced anal squamous cell cancer, highlights current knowledge gaps in the management of anal cancer, and discusses future directions.

Perineal body squamous cell carcinoma treated with radical radiotherapy - a case report

Introduction

Perianal tumours are a rare site of malignancy, and tumours primarily involving the perineal body without vaginal and anal canal involvement are uncommon.

Case summary

A 67-year-old woman presented with a lesion involving the perineum and rectovaginal septum without extension into vaginal or anorectal mucosa and with skip lesions in the vulva. Biopsy was confirmative of squamous cell carcinoma, with p16 positive. A complete metastatic workup with MRI of the pelvis and CECT thorax and abdomen was done. She was diagnosed with perianal carcinoma stage cT2N0M0 Stage II (American Joint Committee on Cancer 8th Edition of Cancer Staging) since the lesion reached the anal verge. Given the location of the tumour (perineal body), comorbidities and advanced age, she received radical radiotherapy with an intensity-modulated radiotherapy technique - 56 Gy in 28 fractions with the intention of organ preservation. The response assessment with MRI at 3 months showed a complete tumour response. She has been disease-free for 3 years and is on regular follow-ups.

Conclusion

Isolated perineal body squamous cell carcinomas are unusual, and synchronous vulvar skip lesion makes this case unique. Radical radiotherapy achieved organ preservation with tumour control and minimal toxicity in an elderly frail patient.

Accuracy of magnetic resonance imaging in defining dentate line in anal fistula

Purpose

To retrospectively assess the accuracy of magnetic resonance imaging (MRI) in defining dentate line in anal fistula.

Materials and methods

Seventy patients with anal fistulas were assessed by dynamic contrast-enhanced MRI. The distance from the dentate line to the anal verge for all patients was measured by MRI. To mitigate interference, 35 patients with anal fistulas whose internal openings were located on the dentate line were excluded from this study. Two observers independently judged the positional relationship between the internal opening and the MRI-defined dentate line, and compared with the results observed by surgeon to assess the accuracy.

Results

The distance between the MRI-defined dentate line and the anal verge depended on the location of the internal opening and the morphology of the anal canal mucosa. The distance based on the location the internal opening and the morphology of the anal canal mucosa was 18.2 ± 8.1 mm and 20.0 ± 5.3 mm on oblique coronal T2WI, respectively. Compared with the results observed by the surgeon, the accuracy of evaluating the positional relationship between the internal opening and the dentate line from the morphology of the anal canal mucosa on MRI exceeded 89.9%. Taking 18.2–20.0 mm as the distance between the dentate line and the anal verge on the MRI image, the accuracy of evaluating the relationship between the position of the internal opening and the dentate line was over 85.7%. Considering both the dentate line and the anal canal mucosa, the accuracy of evaluating the relationship between the internal opening and the dentate line was over 91.5%. The results of MRI-defined dentate line were in good agreement with the results of intraoperative surgeon evaluation, and the κ values were 0.70, 0.63, and 0.78, respectively.

Conclusion

MRI has high accuracy in defining the dentate line in anal fistulas.

Combined PET-CT and MRI for response evaluation in patients with squamous cell anal carcinoma treated with curative-intent chemoradiotherapy

OBJECTIVES

To assess the effectiveness of fluorine-18 fluorodeoxyglucose (FDG) positron-emission tomography-computed tomography (PET-CT) and magnetic resonance imaging (MRI) for response assessment post curative-intent chemoradiotherapy (CRT) in anal squamous cell carcinoma (ASCC).

METHODS

Consecutive ASCC patients treated with curative-intent CRT at a single centre between January 2018 and April 2020 were retrospectively identified. Clinical meta-data including progression-free survival (PFS) and overall survival (OS) outcomes were collated. Three radiologists evaluated PET-CT and MRI using qualitative response assessment criteria and agreed in consensus. Two-proportion z test was used to compare diagnostic performance metrics (sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy). Kaplan-Meier analysis (Mantel-Cox log-rank) was performed.

RESULTS

MRI (accuracy 76%, PPV 44.8%, NPV 95.7%) and PET-CT (accuracy 69.3%, PPV 36.7%, NPV 91.1%) performance metrics were similar; when combined, there were statistically significant improvements (accuracy 94.7%, PPV 78.9%, NPV 100%). Kaplan-Meier analysis demonstrated significant differences in PFS between responders and non-responders at PET-CT (p = 0.007), MRI (p = 0.005), and consensus evaluation (p < 0.001). Cox regression analysis of PFS demonstrated a lower hazard ratio (HR) and narrower 95% confidence intervals for consensus findings (HR = 0.093, p < 0.001). Seventy-five patients, of which 52 (69.3%) were females, with median follow-up of 17.8 months (range 5-32.6) were included. Fifteen of the 75 (20%) had persistent anorectal and/or nodal disease after CRT. Three patients died, median time to death 6.2 months (range 5-18.3).

CONCLUSION

Combined PET-CT and MRI response assessment post-CRT better predicts subsequent outcome than either modality alone. This could have valuable clinical benefits by guiding personalised risk-adapted patient follow-up.

KEY POINTS

• MRI and PET-CT performance metrics for assessing response following chemoradiotherapy (CRT) in patients with anal squamous cell carcinoma (ASCC) were similar. • Combined MRI and PET-CT treatment response assessment 3 months after CRT in patients with ASCC was demonstrated to be superior to either modality alone. • A combined MRI and PET-CT assessment 3 months after CRT in patients with ASCC has the potential to improve accuracy and guide optimal patient management with a greater ability to predict outcome than either modality alone.

Anorectal pathology in the HIV population: a guide for radiologists

Patients with human immunodeficiency virus (HIV) can present with a wide range of different acute and chronic pathologies. Anorectal conditions are particularly common in this unique patient population, including pathologies, such as proctitis, anorectal abscess, anorectal fistula, and anal squamous cell carcinoma. The radiologist plays a critical role in the assessment of these common forms of anorectal disease, as these conditions can present with various findings on imaging assessment. Pelvic CT, MRI, and FDG-PET/CT are among the most common modalities used for assessment of anorectal disease in the HIV patient population. Knowledge of the fundamental clinical and imaging findings associated with these pathologies in HIV patients is critical for radiologists.

Overview of the Large Bowel Assessment Using Magnetic Resonance Imaging: Different Techniques for Current and Emerging Clinical Applications

Radiological assessments of the small and large bowel are essential in daily clinical practice. Over plain film X-ray and ultrasound, cross-sectional techniques are considered the most comprehensive imaging modalities. In fact, computed tomography and magnetic resonance imaging take great advantage of the three-dimensional appraisal and the extensive evaluation of the abdominal cavity, allowing intestinal evaluation as well as detection of extra-intestinal findings. In this context, the chief advantage of computed tomography is the fast scan time, which is crucial for emergency cases. Nonetheless, it is undeniably impaired using ionizing radiation. As the awareness of radiation exposure is a topic of increasing importance, magnetic resonance imaging is not only becoming a mere alternative but also a primary imaging technique used in assessing intestinal diseases. Specifically, the evaluation of the large bowel through MRI can be still considered relatively uncharted territory. Although it has demonstrated superior accuracy in the assessment of some clinical entities from inflammatory bowel disease to rectal carcinoma, its role needs to be consolidated in many other conditions. Moreover, different technical methods can be applied for colonic evaluation depending on the specific disease and segment involved. This article aims to provide a thorough overview of the techniques that can be utilized in the evaluation of the large bowel and a discussion on the major findings in different colonic pathologies of primary interest.

Synchronous occurrence of HPV-associated cervical squamous cell carcinoma (FIGO IIA) in prolapsed uterus and adenocarcinoma of the anal canal cT1N0M0: Case report

RATIONALE

Guidelines of rare synchronous tumours treatment are often unavailable due to lack of wide prospective studies. Additionally, their management is not just a simple sum of coexisting tumours management and has to regard many circumstances like symptoms, age, comorbidities, advancement.

PATIENT CONCERNS

Herein, we report a case of an 81-year-old woman who presented with bleeding from the prolapsed uterus.

DIAGNOSES

Based on physical examination, that is, speculum examination, bimanual, and per rectum, followed by rectoscopy and histopathology, the diagnosis of cervical squamous cell carcinoma FIGO IIA2 in prolapsed uterus with anal canal adenocarcinoma cT1N0M0 was made.

INTERVENTIONS

Dominating complaint of bleeding from prolapsed cervix was managed with radical vaginal hysterectomy in conjunction with wide colpectomy preceded by laparoscopic pelvic and paraaortic lymphadenectomy. Due to the lack of consent for removal of the anus, only radiotherapy was applied instead.

OUTCOMES

The patient underwent magnetic resonance image follow-up. No recurrence was found at 18 months.

LESSONS

Imaging is useful method of synchronous cancers diagnostics. These cancers may vary in aetiology and stage. Cervical cancer may be co-existing with another anogenital cancer. Therapy of synchronous cancers should be individualized taking into account patient's consent, age, physical condition, and comorbidities.

Assessment of Apparent Diffusion Coefficients and SUVs as Predicators of Histological Differentiation in Anal Squamous Cell Carcinoma

AIM

The study aims to assess minimal apparent diffusion coefficient (ADCmin) and SUVmax as predictors of histological differentiation in patients with anal squamous cell carcinoma (ASCC) and to determine cutoff values for each histopathological tumor grade.

PATIENTS AND METHODS

A retrospective study of 41 ASCC patients (14 males, 27 females; mean age, 65 ± 13 years) staged with FDG PET/CT and MRI (mean scan time interval, 21 ± 11 days). SUVmax and ADCmin values were measured and compared with histopathological tumor grading obtained from biopsy.

RESULTS

The mean size and tumor volume were 3 ± 2 cm and 16.5 ± 27.3 cm3, respectively. The mean ADCmin values for well-, moderately, and poorly differentiated ASCC were 935 ± 179, 896 ± 123, and 637 ± 114, respectively. The mean SUVmax for well-, moderately, and poorly differentiated ASCC were 6.9 ± 1.8, 11.5 ± 4.1, and 13.4 ± 2.6, respectively. The difference in mean ADCmin values between poorly and moderately/well-differentiated tumors was statistically significant, whereas this was not significant between moderately and well-differentiated tumors. Differences in SUVmax values were statistically significant between poorly/moderately and well-differentiated tumors, whereas there was no statistical significance between poorly and moderately differentiated tumors. By combining the 2 modalities using cutoff values of 675 × 10-6 mm2·s-1 for ADCmin and 8.5 for SUVmax, it was possible to differentiate the tumor categories with a sensitivity, specificity, positive predictive value, and negative predictive value, respectively, of 84.6%, 96.4%, 91.7%, and 93.1% for well-differentiated ASCC, 76.5%, 87.5%, 81.3%, and 84% for moderately, and 90.9%, 89.3%, 76.9%, and 96.2% for poorly differentiated ASCC, respectively.

CONCLUSIONS

ADCmin and SUVmax values correlated with the degree of differentiation in ASCC and can be used as predictors of tumor grading and aggressiveness. Combined ADCmin and SUVmax cutoff values can therefore be used for early patient risk stratification and treatment decision making.

Prognostic and Predictive Clinical and Biological Factors in HPV Malignancies

Human papillomavirus (HPV) causes the majority of oropharyngeal, cervical, and anal cancers, among others. These HPV-associated cancers cause substantial morbidity and mortality despite ongoing vaccination efforts. Aside from the earliest stage tumors, chemoradiation is used to treat most HPV-associated cancers across disease sites. Response rates are variable, and opportunities to improve oncologic control and reduce toxicity remain. HPV malignancies share multiple commonalities in oncogenesis and tumor biology that may inform personalized methods of screening, diagnosis, treatment and surveillance. In this review we discuss the current literature and identify promising molecular targets, prognostic and predictive clinical factors and biomarkers in HPV-associated oropharyngeal, cervical and anal cancer.

Squamous Cell Carcinoma of the Anus Incidence, Mortality, and Survival Among the General Population and Persons Living With HIV in Puerto Rico, 2000-2016

PURPOSE

Squamous cell carcinoma of the anus (SCCA) is common among persons living with HIV (PLWH). We described SCCA incidence and survival among the general population and among PLWH in Puerto Rico (PR), along with mortality of anal cancer.

METHODS

PR HIV/AIDS Surveillance Program and the PR Central Cancer Registry databases were linked (2000-2016). Incidence rates (IRs) and trends (annual percent change [APC]) in SCCA and mortality rates and trends for anal cancer were estimated. Relative survival and relative excess risk (RER) of death were calculated.

RESULTS

From 2000 to 2016, 991 individuals in PR were diagnosed with anal cancer; 73% of cases were SCCA 9.1% of SCCA and 1.5% of non-SCCA cases were in PLWH (P < .0001). SCCA incidence was higher among PLWH than the general population (IR = 27.7/100,000). Among PLWH, SCCA incidence (per 100,000) was the highest among men who have sex with men (IR = 60.5). From 2001-2016, SCCA incidence increased among the general population (APC: 4.90, P < .05); however, no significant change was observed among PLWH (APC = 0.19 and P = .96). The APC for anal cancer mortality in the general population was positive (3.9%) from 2000 to 2016, but not significant (P > .05). The 5-year relative survival of SCCA was 56.9% among PLWH and 66.8% among the general population. In multivariate analysis, the RER of death for SCCA 5 years postdiagnosis was affected by stage at diagnosis (distant: RER = 7.6, 95% CI, 2.36 to 24.25) but not by PLWH status (RER = 1.4, 95% CI, 0.67 to 3.01).

CONCLUSION

Our findings highlight the relevance of anal cancer screening in PLWH and HPV vaccination in both PLWH and the general population in PR, which could have an impact on the disease trend in the next few decades.

Magnetic Resonance Imaging of the Anal Region: Clinical Applications

Over the past years, magnetic resonance imaging (MRI) has become a cornerstone in evaluating anal canal and adjacent tissues due to its safeness, the three-dimensional and comprehensive approach, and the high soft-tissue resolution. Several diseases arising in the anal canal can be assessed through MRI performance, including congenital conditions, benign pathologies, and malignancies. Good knowledge of the normal anatomy and MRI technical protocols is, therefore, mandatory for appropriate anal pathology evaluation. Radiologists and clinicians should be familiar with the different clinical scenarios and the anatomy of the structures involved. This pictorial review presents an overview of the diseases affecting the anal canal and the surrounding structures evaluated with dedicated MRI protocol.

Circulating CD14+ HLA-DRlo/- monocytic cells as a biomarker for epithelial ovarian cancer progression

PROBLEM

Previous studies identified circulating CD14⁺ HLA-DR^lo/- monocytic cells as an immune suppressive subset in solid malignancies, such as prostate, renal cell carcinoma, and pancreatic cancer. Such monocytic cells have been implicated not only in tumour progression but also as a potential barrier for immunotherapy. This study examined the relationship between the frequency of circulating monocytic cells and epithelial ovarian cancer (EOC) progression pre- and post-frontline chemotherapy, defined by disease stage, which is a leading prognostic factor for this malignancy.

METHOD OF STUDY

Incident cases of 236 women with EOC were recruited and comprehensive flow cytometry was utilized to assess the frequency of peripheral blood CD33⁺ CD11b⁺ HLA-DR^-/low CD14⁺ CD15^- monocytic cells, henceforth termed CD14⁺ HLA-DR^lo/- monocytic cells, prior to and after completion of frontline chemotherapy. Multivariable odds ratios (OR) were used to estimate the association between CD14⁺ HLA-DR^lo/- monocytic cell percentages and disease stage. Wilcoxon signed-rank tests evaluated changes in these monocytic cell levels pre- and post-chemotherapy in a patient subset (n = 70).

RESULTS

Patients with elevated frequencies of circulating CD14⁺ HLA-DR^lo/- monocytic cells at diagnosis were at 3.33-fold greater odds of having advanced stage (III/IV) EOC (CI: 1.04-10.64), with a significant trend in increasing CD14⁺ HLA-DR^lo/- monocytic cell levels (P = .04). There was a 2.02% median decrease of these monocytic cells post-chemotherapy among a subset of patients with advanced stage disease (P < .0001).

CONCLUSION

These findings support the potential clinical relevance of CD14⁺ HLA-DR^lo/- monocytic cells in EOC for prognosis and may indicate a non-invasive biomarker to measure disease progression.

Additional Value of 2-[18F]FDG PET/CT Comparing to MRI in Treatment Approach of Anal Cancer Patients

Accurate staging and treatment planning are imperative for precise management in Anal Cancer (ACa) patients. We aimed to evaluate the additive and prognostic value of pre-treatment 2-[¹⁸F]fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (2-[¹⁸F]FDG PET/CT) in the staging and management of ACa compared to magnetic resonance imaging (MRI). This retrospective study was conducted on 54 patients. Pre-treatment 2-[¹⁸F]FDG PET/CT studies and MRI reports were compared considering the primary tumor, pelvic lymph nodes, and metastatic lesions. The impact of 2-[¹⁸F]FDG PET/CT in the management and its prognostic value, using maximum standardized uptake value (SUVmax), were assessed. Discordant findings were found in 46.3% of patients (5 in T; 1 in T and N; 18 in N; and 1 in M stage). 2-[¹⁸F]FDG PET/CT resulted in up-staging in 9.26% and down-staging in 3.7% of patients. Perirectal lymph nodes were metabolically inactive in 12.9% of patients. Moreover, 2-[¹⁸F]FDG PET/CT resulted in management change in 24.1% of patients. Finally, SUVmax provided no prognostic value. 2-[¹⁸F]FDG PET/CT altered staging and management in a sizable number of patients in this study, and supports a need for a change in guidelines for it to be used as a routine complementary test in the initial management of ACa.

Racial/Ethnic Disparities in Survival Among Women Diagnosed with Invasive Cancer of the Anal Canal: an Analysis of Surveillance, Epidemiology, and End Results (SEER) Data

OBJECTIVE

To identify differences in survival among women diagnosed with cancer of the anal canal from varying racial and ethnic backgrounds.

METHODS

Data from the Surveillance, Epidemiology and End Results (SEER) registry between the years of 1975 and 2016 were analyzed, which included 19,048 women with cancer of the anal canal. Multivariable Cox proportional hazard regression (HRs) was performed to examine the relative risk of dying among women with anal cancer. Multivariable odds ratios (ORs) with 95% confidence intervals (CIs) were used to examine odds of highly fatal disease (death within 12 months from diagnosis).

RESULTS

Non-Hispanic Black women (n = 1694) had greater risk of dying when compared with non-Hispanic White women (n = 15,821) with anal cancer (HR = 1.26, CI: 1.17-1.35), independent of other prognostic indicators. Stratifying by age at diagnosis, risk of death was highest for non-Hispanic Black women diagnosed younger than age 50 years compared with non-Hispanic White women of similar age (HR = 1.60, CI: 1.34-1.89), and lowest for Hispanic women (n = 1533) older than 74 years at diagnosis (HR = 0.80, CI: 0.69-0.92). Stratifying by stage at diagnosis, disparities were not observed. When comparing across years of diagnoses, non-Hispanic Black women consistently had poorer survival compared with non-Hispanic White women diagnosed in the same year intervals. Finally, non-Hispanic Black women had greater odds of highly fatal disease (OR = 1.23, CI: 1.08-1.40) compared with non-Hispanic White women.

CONCLUSION

Non-Hispanic Black women with anal cancer continue to experience poorer survival compared with non-Hispanic White women, whereas disparities were not identified for Hispanic women.

A 2020 update of anal cancer: the increasing problem in women and expanding treatment landscape

INTRODUCTION

Anal cancer is a rare malignancy with increasing incidence, notably in women. This disease is highly associated with HPV infection and its incidence and mortality are currently rising. Most patients present with localized disease which has a high survival after definitive treatment with chemoradiation. For patients who develop metastatic disease or present with this de novo, survival is poor.

AREAS COVERED

This review provides a summary of current literature on anal cancer. With a focus on women, this includes current epidemiological trends, role of HPV, and the current and future treatment landscape, including HPV vaccination and immunotherapy. Screening currently focusses on HIV-positive men, missing most female cases. In curative disease, trials are investigating treatment de-intensification in good prognostic groups. Immunotherapy is showing early promise in the advanced disease setting.

EXPERT OPINION

Similar to cervical cancer, anal cancer is strongly associated with HPV, and therefore, broader implementation of screening programs may reduce its incidence. HPV vaccination is expected to reduce the development of (pre)malignant anal lesions. The emergence of biomarkers will assist patient treatment selection, allowing optimal balance of treatment efficacy and morbidity. It is hoped that new treatment approaches, including immunotherapy, will improve outcomes. International collaboration is needed.

Prognostic role of ultrasonography staging in patients with anal cancer

BACKGROUND

Carcinomas of the anal canal are staged according to the size and extent of the disease; however, we propose including a novel ultrasound (US) staging system, based on depth of tumor invasion. In this study the clinical American Joint Committee on Cancer (AJCC) staging guidelines and the US classificationss in patients with anal cancer were compared.

AIM

To evaluate the prognostic role of the US staging system in patients with anal cancer.

METHODS

The data of 48 patients with anal canal squamous cells carcinoma, observed at our University Hospital between 2007 and 2017, who underwent pre-treatment assessment with pelvic magnetic resonance imaging (MRI), total body computed tomography (CT) scan and endoanal US were retrospectively reviewed. Anal canal tumors were clinically staged according to AJCC, determined by MRI by measurement of the longest tumor diameter, and CT scan. Endoanal US was performed with a high multi-frequency (9-16 MHz), 360° rotational mechanical probe; US classification was based on depth of tumor penetration through the anal wall, according to Giovannini’s study. All patients were treated with definitive radiation combined with 5-fluorouracile and Mitomycin-C. After treatment patients were followed-up regularly.

RESULTS

At baseline there were 30 and 32 T1-2, 18 and 16 T3-4, 31 and 19 N+ patients classified according to the clinical AJCC and US staging system respectively. After a mean follow-up of 98 months, 38 patients (79.1%) are alive and 28 (58.3%) are disease free. During follow up 20 patients (41.6%) experienced recurrences. After univariate analysis, American Society of Anesthesiologists (ASA) score (P = 0.00000001) and US staging (P = 0.009) were significantly related to disease-free survival (DFS). When overall survival and DFS functions were compared, a statistically significant difference was observed for DFS survival when the US staging was applied with respect to the clinical AJCC staging. By combining the 2 significant prognostic variables, namely the US staging with the ASA score, four risks groups with different prognoses were identified.

CONCLUSION

Our findings suggest that US staging may be superior to traditional clinical staging, since it is significantly associated with DFS in anal cancer patients.

Cancer attributable to human papillomavirus infection in China: Burden and trends

BACKGROUND

Human papillomavirus (HPV) is associated with a substantial percentage of cervical cancer, and a significant percentage of anal, penile, vaginal, vulvar, oral cavity, oropharyngeal, and laryngeal cancers. Understanding the burden and trends of HPV-attributable cancers is crucial to HPV prevention strategies. In the current study, the authors estimated the latest burden and trends of HPV-attributable cancers in China.

METHODS

Data from the following sources were used. The number of new cancer cases and cancer deaths in China were estimated based on the China Cancer Registry Annual Report. The population-attributable fraction was estimated using pooled high-risk HPV prevalence and biomarker-positive rates, which were calculated using random effects meta-analyses. Cancer burden estimates were stratified by anatomic site, sex, and age.

RESULTS

In 2015, a total of 110,650 new cancer cases and 36,714 cancer deaths attributable to HPV infection were estimated to have occurred in China, of which cervical cancer accounted for 85.6% and 78.1%, respectively. The age-standardized incidence rate (ASIR) and age-standardized mortality rate (ASMR) of HPV-attributable cancers were 5.63 and 1.81 per 100,000 person-years, respectively. The ASIR and ASMR both varied by anatomic site, with the highest rates noted for cervical cancer at 4.83 and 1.42 per 100,000 person-years, respectively. Between 2005 and 2015, the ASIR and ASMR demonstrated significant upward trends for all HPV-attributable cancers combined.

CONCLUSIONS

Between 2005 and 2015, cervical cancer accounted for the vast majority of HPV-attributable cancers and its incidence and mortality increased rapidly in China. The comprehensive prevention of cervical cancer remains the most important target in the prevention of HPV-attributable cancers.

Rectal cancer lexicon: consensus statement from the society of abdominal radiology rectal & anal cancer disease-focused panel

Standardized terminology is critical to providing consistent reports to referring clinicians. This lexicon aims to provide a reference for terminology frequently used in rectal cancer and reflects the consensus of the Society of Abdominal Radiology Disease Focused Panel in Rectal cancer. This lexicon divided the terms into the following categories: primary tumor staging, nodal staging, treatment response, anal canal anatomy, general anatomy, and treatments.

MR staging of anal cancer: what the radiologist needs to know

Anal canal cancer is a rare disease and squamous cell carcinoma is the most common histologic subtype. Traditionally, anal cancer is imaged with CT and PET/CT for purposes of TNM staging. With the increased popularity of MRI for rectal cancer evaluation, MRI has become increasingly utilized for local staging of anal cancer. In this review, we focus on the necessary information radiologists need to know to understand this rare and unique disease and to be familiar with staging of anal cancer on MRI.

Ischiorectal fossa: benign and malignant neoplasms of this "ignored" radiological anatomical space

PURPOSE

To review the pertinent anatomy and the imaging features of common and uncommon benign and malignant neoplasms and masses of the ischiorectal fossa.

RESULTS

The ischiorectal or ischioanal fossa is the largest space in the anorectal region. The benign neoplasms that develop in the ischiorectal originate from the different components that forms the fossa including vascular tumors such as aggressive angiomyxoma or hemangioma; neural tumors as plexiform neurofibroma or schwannoma; fat tumors as lipoma; skin/skin appendages tumors as hidradenoma papilliferum; smooth or skeletal muscle tumors as solitary fibrous tumor. The malignant neoplasms that develop in the ischiorectal fossa also originate from different components that forms the fossa including vascular tumors such as angiosarcoma, neural tumors as malignant granular cell tumor and malignant peripheral nerve sheath tumor; fat tumors as liposarcoma; smooth or skeletal muscle tumors as leiomyosarcoma, rhabdomyosarcoma, malignant PEComa, or undifferentiated pleomorphic sarcoma. Additionally, the ischiorectal fossa can also harbor secondary hematogenous metastases and be affected by direct invasion from neoplasms of adjacent pelvic organs and structures. Furthermore, other miscellaneous masses can occur in the ischiorectal fossa including congenital and developmental lesions, and inflammatory and infectious processes.

CONCLUSION

Knowledge of the anatomy, and the spectrum of imaging findings of common and uncommon benign and malignant neoplasms of the ischiorectal fossa is crucial for the radiologists during interpretation of images allowing them to make contributions to the diagnosis and better patient management.

MRI evaluation of anal and perianal diseases

Anal and perianal region is a commonly affected area in the course of several inflammatory, infectious, and neoplastic diseases. Several imaging modalities may be used in imaging evaluation of this area and magnetic resonance imaging (MRI) emerges as the imaging modality of choice due to its superb soft tissue resolution. MRI is not only useful for initial detection of anal/perianal pathologies but also in the follow-up of these disorders. In this article, we aimed to illustrate MRI findings of several diseases affecting this area including perianal fistula as well as anal fissure, hypertrophic myopathy of internal anal sphincter, hidradenitis suppurativa, pilonidal sinus, rectovaginal/anovaginal fistula and anal canal carcinoma. We think that this article will serve to familiarize the imaging specialists to the MRI findings of these diseases.

Can MR imaging be useful in differentiating low rectal cancer from anal cancer?

PURPOSE

To evaluate the role of pelvic MR imaging in differentiating between low rectal and anal cancers using the pathological results as the gold standard.

MATERIALS AND METHODS

In this study, retrospective analysis of 100 patients with a history of low rectal (n = 50) or anal (n = 50) cancers who underwent staging pelvic MR imaging before treatment was performed. The following parameters were analyzed: distance from the anal verge to the tumor, percentage of tumor above puborectalis muscle, tumor size, T2W signal intensity, sphincter/levator muscles invasion, organ invasion, and MRI diagnosis. Multivariable logistic regression was performed to determine factors associated with low rectal and anal cancers. Distances from the anal verge to the tumor were compared using receiver-operating characteristic (ROC) curves.

RESULTS

From the ROC curves, the cut-off value for the distance from the anal verge to the tumor in differentiating between low rectal and anal cancers was 2.1 cm and the area under the ROC curve was 0.90 (95% CI 0.84-0.97). Multivariate logistic regression revealed three significant factors in differentiating between low rectal and anal cancers, including T2 mixed hyper- and hyposignal intensity (OR 66.00, 95% CI 4.66-934.81), distance cut-off value (OR 34.72, 95% CI 5.73-210.27), and absence of sphincter invasion (OR 18.75, 95% CI 1.91-183.96), with sensitivity, specificity, PPV, and NPV of 98%, 88%, 89%, and 97%, respectively, and diagnostic accuracy increased from 79% (reader 1) and 82% (reader 2) to 93%.

CONCLUSION

MR imaging can be useful to differentiating between low rectal and anal cancers which benefits staging and treatment planning.

Value of high resolution magnetic resonance imaging in preoperative staging of rectal cancer

AIM

To assess the value of conventional magnetic resonance imaging (MRI) combined with high resolution MRI (HR-MRI) in preoperative T and N staging of rectal cancer by comparing with pathological staging.

METHODS

The clinical data of 84 patients with primary rectal cancer who were admitted to Tianjin Haibin People's Hospital from January 2017 to October 2017 and underwent conventional MRI and HR-MRI preoperatively and pathological examination postoperatively were collected. The consistency and correlation were analyzed between preoperative T and N staging by conventional MRI and HR-MRI and pathological T and N staging. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of conventional MRI combined with HR-MRI in diagnosing T and N stages were calculated.

RESULTS

There was a strong consistency between preoperative T and N staging by conventional MRI and HR-MRI and pathological T and N staging (κ = 0.691, P = 0.000), and the correlation rate was 84.52% (71/84). The accuracy, sensitivity, and specificity of conventional MRI and HR-MRI were 93.15%, 87.44%, and 92.36% for preoperative T1 staging, 91.23%, 86.19%, and 95.42% for preoperative T2 staging, 93.15%, 87.44%, and 92.36% for preoperative T3 staging, and 95.24%, 100.00%, and 77.78% for preoperative T4 staging. The accuracy, sensitivity, and specificity of conventional MRI combined with HR-MRI for preoperative N staging were 93.15%, 87.44%, and 92.36%, respectively. Using postoperative pathological results as the "gold standard", the accuracy, specificity, and sensitivity of conventional MRI combined with HR-MRI in predicting mesorectal invasion before surgery were 93.15%, 87.44%, and 92.36%, respectively.

CONCLUSION

Conventional MRI combined with HR-MRI has high diagnostic value in preoperative evaluation of T and N stages and mesangial invasion in patients with rectal cancer, which can provide a reliable reference for the clinical planning of surgical procedures.