The assessment of local response using magnetic resonance imaging at 3- and 6-month post chemoradiotherapy in patients with anal cancer

Standard versus reduced-dose chemoradiotherapy in anal cancer (PLATO-ACT4): short-term results of a phase 2 randomised controlled trial

BACKGROUND

Localised squamous cell carcinoma of the anus is treated with radical chemoradiotherapy. Cure rates are high, but treatment can result in substantial acute and long-term morbidity. We aimed to assess whether lower dose chemoradiotherapy maintains high local control rates in patients with early-stage disease, with the secondary aim of reducing toxicity.

METHODS

ACT4 is a phase 2, prospective, multicentre, open-label, two-arm non-comparative, randomised, controlled trial, investigating reduced-dose intensity-modulated radiotherapy (rd-IMRT: 41·4 Gy in 23 fractions) in patients with early-stage anal cancer; T1-2 (≤4 cm) N0-NxM0. Eligible patients were at least 16 years of age, with an Eastern Cooperative Oncology Group performance status of 0-1. The primary outcome is 3-year loco-regional failure rates. Patients were randomly assigned 1:2 (with stratification by T stage, N stage, gender, HIV status, and randomising site) to standard-dose IMRT (sd-IMRT: 50·4 Gy in 28 fractions) or rd-IMRT with concurrent mitomycin and capecitabine chemotherapy. Here, we report the pre-planned, modified intention-to-treat analysis of secondary endpoints 6 months after treatment end-complete clinical response, compliance, patient-reported outcomes (EORTC QLQ-C30 and ANL27), and safety data. The trial is registered at the ISRCTN registry (ISRCTN88455282) and is ongoing but no longer recruiting.

FINDINGS

163 patients were recruited from 28 UK tertiary centres between April 24, 2017, and Dec 1, 2020. 160 patients were included in the primary analysis (sd-IMRT n=55; dr-IMRT n=105). Data on ethnicity were not collected. The median patient age was 66 years (IQR 58-72 years); 117 (73%) were female and 43 (27%) male; and 129 (94%) of 138 evaluable samples were p16 positive. Complete clinical responses at 6 months were 87% (46 of 53) for sd-IMRT and 92% (89 of 97) for rd-IMRT. Radiotherapy interruptions of 3 days or more occurred in 14 (26%) of 55 patients in sd-IMRT and 16 (15%) of 105 patients in rd-IMRT. Chemotherapy modifications occurred in 27 (49%) of 55 patients in sd-IMRT and 39 (37%) of 105 patients in rd-IMRT. Grade 3 or worse acute toxicity was reported in 25 (46%) of 55 patients in sd-IMRT and 37 (35%) of 105 patients in rd-IMRT. The most common grade 3 or worse adverse events were radiation dermatitis (seven [13%] of 55 in sd-IMRT and ten [10%] of 105 in rd-IMRT), and diarrhoea (four [7%] of 55 in sd-IMRT and nine [9%] of 105 in rd-IMRT). Serious adverse events occurred in eight (15%) of 55 patients in sd-IMRT and ten (10%) of 105 patients in rd-IMRT. Patient-reported outcomes for most issues deteriorated at the end of treatment and resolved to baseline by 6 weeks in both groups. Poorer sexual function for men and women was observed at 6 months following sd-IMRT.

INTERPRETATION

Good 6-month complete clinical responses rates were seen in both groups. Early results suggest rd-IMRT is well tolerated with oncological outcomes maintained. 3-year locoregional failure rates are awaited.

FUNDING

Cancer Research UK and Stand Up to Cancer.

Expert Panel on Gastrointestinal Imaging, Horvat N, Liu PS, Fowler KJ, Birkholz JH, Cash BD, Dane B, Eng C, Kambadakone AR, Korngold EK, Pietryga JA, Refaat T, Santillan CS, Surasi DS, Woolsey S, Kim DH. ACR Appropriateness Criteria® Staging and Follow-up of Anal Cancer

This document aims to provide recommendations on the role of imaging in the diagnosis of squamous cell anal cancer, focusing on its use in locoregional and systemic assessment during initial staging, posttreatment evaluation, and surveillance. For initial locoregional staging, MRI of the pelvis and FDG-PET/CT are usually appropriate to complement clinical and digital rectal examinations, because they offer additional information regarding locoregional tumor invasion and nodal metastases. For metastatic disease assessment, which is rare in the initial presentation and commonly associated with recurrence-with lymph nodes, liver, and lungs being the most common sites of disease-CT and FDG-PET/CT are usually appropriate for detecting distant nodal metastases and other sites of metastatic disease. MRI of the abdomen may be appropriate as a problem-solving tool, particularly in assessing small or indeterminate liver lesions. For patients who have completed locoregional treatment, most typically achieve clinical complete response; consequently, few require surgery unless there is persistent disease or recurrence. The role of posttreatment imaging assessment is still debatable; however, in cases in which surgery is indicated, MRI and FDG-PET/CT are usually appropriate for assessing local tumor invasion and nodal metastases. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Imaging Features of Anal Carcinoma after Chemoradiation

Anal cancer is a rare malignancy that is primarily treated with chemoradiation therapy (CRT). Clinical examination of the anal canal after CRT is often limited owing to the patient's discomfort. Therefore, radiologic surveillance plays a fundamental role in treatment response assessment. Currently recommended imaging modalities for posttreatment follow-up include pelvic MRI for local response evaluation and CT for evaluation of possible distant metastases. Patients who demonstrate a complete treatment response undergo regular clinical and imaging surveillance. Cases demonstrating an equivocal treatment response, an incomplete response, or disease progression should be streamlined for biopsy confirmation of the suspicious site and considered for salvage abdominoperineal resection. Radiologic differentiation of post-CRT inflammatory changes versus residual tumor, particularly in the early post-CRT period, can be challenging. However, careful interrogation of T2-weighted MR images correlated with matching diffusion-weighted and apparent diffusion coefficient images can increase reader confidence. The role of fluorine 18-fluorodeoxyglucose (FDG) PET/CT in assessing the response to anal cancer treatment is a debated topic. However, emerging research suggests that FDG PET/CT is complementary to pelvic MRI for accurate treatment response assessment, providing additional metabolic information. In this article, the authors provide a comprehensive review of the post-CRT imaging appearances of anal cancer, including examples from the spectrum of disease responses and therapy-related complications, and describe the strengths and limitations of pelvic MRI and FDG PET/CT. The authors also share the pearls and pitfalls in differentiating residual tumor from posttreatment inflammatory mimics. ©RSNA, 2025 Supplemental material is available for this article.

Radiation Therapy for Anal Squamous Cell Carcinoma: An ASTRO Clinical Practice Guideline

PURPOSE

This guideline provides evidence-based recommendations addressing the indications for definitive treatment of primary squamous cell carcinoma of the anal canal and anal margin.

METHODS

The American Society for Radiation Oncology convened a task force to address 4 key questions focused on (1) indications for radiation therapy (RT), concurrent systemic therapy and local excision/surgery, (2) appropriate RT techniques, (3) appropriate RT dose-fractionation regimens, target volumes, and dose constraints, and (4) appropriate surveillance strategies after definitive treatment. Recommendations are based on a systematic literature review and created using a predefined consensus-based methodology and system for grading evidence quality and recommendation strength.

RESULTS

Multidisciplinary evaluation and decision-making are recommended for all patients. Definitive treatment with combined modality therapy is recommended for most patients using concurrent 5-fluorouracil or capecitabine plus mitomycin, with cisplatin as a conditional alternative to mitomycin with RT. Select patients with early-stage disease may be considered for local excision alone. RT target volumes should include the primary tumor/anal canal and rectum, and mesorectal, presacral, internal and external iliac, obturator, and inguinal lymph nodes. Intensity modulated RT-based treatment approaches are recommended. The primary tumor should receive doses of 4500 to 5940 cGy in 25 to 33 fractions, and clinically involved lymph nodes should receive 5040 to 5400 cGy in 28 to 30 fractions, depending on disease stage and RT approach. Elective nodal volumes should receive 3600 to 4500 cGy in 20 to 30 fractions, depending on disease stage and RT approach. Dose guidance for normal tissues and measures to minimize acute and chronic treatment-related toxicity are provided. Treatment breaks should be minimized. Posttreatment surveillance strategies, including timing of clinical/digital exam, anoscopy, computed tomography, magnetic resonance imaging, and positron emission tomography/computed tomography, are discussed.

CONCLUSIONS

These evidence-based recommendations guide clinical practice on the use of definitive therapy for localized anal squamous cell carcinoma. Future studies will further refine the optimal RT dose for early- and advanced-stage disease, use of alternative systemic agents, including immunotherapy, the role of adaptive RT, and other strategies to minimize long-term treatment-related toxicity.

International consensus to define outcomes for trials of chemoradiotherapy for anal cancer (CORMAC-2): defining the outcomes from the CORMAC core outcome set

Variation in outcomes definitions and reporting limit the utility of clinical trial results. The Core Outcome Research Measures in Anal Cancer (CORMAC) project developed a core outcome set (COS) for chemoradiotherapy trials for anal squamous cell carcinoma (ASCC) through an international healthcare professional and patient consensus process. The CORMAC-COS comprises 19 outcomes across 4 domains (disease activity, survival, toxicity, life impact). In CORMAC-2 we have established standardised definitions for the 11 disease activity and survival outcomes in the CORMAC COS. Definitions were agreed through a 3 step process, initially identifying existing definitions through systematic review (registered with PROSPERO, CRD42016036540), using these to populate a two-round Delphi questionnaire completed by 51 experts from 13 countries, and finally ratification through an online consensus meeting. Standardising the definitions for these core outcomes facilitates real world utilisation of the CORMAC-COS, thereby increasing the quality of data available for clinical decision-making and ultimately enhancing patient care.

Anal and Perianal Masses: The Common, the Uncommon, and the Rare

A variety of tumors involve the anal canal because the anal canal forms the transition between the digestive system and the skin, and this anatomical region is made of a variety of different cells and tissues. Magnetic resonance imaging (MRI) is the modality of choice for diagnosis and local staging of the anal canal and perianal neoplasms. In this pictorial review, we demonstrate the MRI anatomy of the anal canal and perianal region and display the imaging spectrum of tumors in the region along with an overview of its management. Imaging appearances of many tumorlike lesions that can cause diagnostic dilemmas are also demonstrated with pointers to differentiate between them.

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.

Outcomes of patients with anal cancer treated with definitive chemoradiation: A single centre experience

Background

Anal cancers are uncommon neoplasms that make up to <1% of all tumours globally. Concurrent chemoradiation remains the standard of care treatment for patients who present with non-metastatic anal squamous cell carcinomas (ASCCs).

Methods

We aimed to evaluate the response rate and 2-year survival outcome of the definitive chemoradiation approach in patients with non-metastatic ASCCs of our population. We conducted a cross-sectional review of these patient populations who were treated and then followed after completion of treatment at our institute during the last 10 years.

Results

A total of 17 patients were enrolled after fulfillment of the eligibility criteria. The responses were documented in 16 patients through magnetic resonance imaging or computed tomography of the pelvis, done at 3 months of treatment completion. More than 80% of the patients had complete radiological responses. Among the surviving participants, the 2-year disease-free survival rate was found to be more than two-thirds. Approximately 20% of the study participants had disease recurrence during the subsequent clinic visits following treatment completion.

Conclusion

This review emphasises the impact of definitive chemo-radiation in achieving radiological and clinical responses in patients with non-metastatic ASCCs. Moreover, to our knowledge, this is the first review to highlight anal cancer's incidence and characteristics in Pakistan.

PET/MRI in colorectal and anal cancers: an update

Positron emission tomography (PET) in the era of personalized medicine has a unique role in the management of oncological patients and offers several advantages over standard anatomical imaging. However, the role of molecular imaging in lower GI malignancies has historically been limited due to suboptimal anatomical evaluation on the accompanying CT, as well as significant physiological 18F-flurodeoxyglucose (FDG) uptake in the bowel. In the last decade, technological advancements have made whole-body FDG-PET/MRI a feasible alternative to PET/CT and MRI for lower GI malignancies. PET/MRI combines the advantages of molecular imaging with excellent soft tissue contrast resolution. Hence, it constitutes a unique opportunity to improve the imaging of these cancers. FDG-PET/MRI has a potential role in initial diagnosis, assessment of local treatment response, and evaluation for metastatic disease. In this article, we review the recent literature on FDG-PET/MRI for colorectal and anal cancers; provide an example whole-body FDG-PET/MRI protocol; highlight potential interpretive pitfalls; and provide recommendations on particular clinical scenarios in which FDG-PET/MRI is likely to be most beneficial for these cancer types.

Diffusion-weighted imaging complements T2-weighted MRI for tumour response assessment in squamous anal carcinoma

OBJECTIVES

A published tumour regression grade (TRG) score for squamous anal carcinoma treated with definitive chemoradiotherapy based on T2-weighted MRI yields a high proportion of indeterminate responses (TRG-3). We investigate whether the addition of diffusion-weighted imaging (DWI) improves tumour response assessment in the early post treatment period.

MATERIALS AND METHODS

This retrospective observational study included squamous anal carcinoma patients undergoing MRI before and within 3 months of completing chemoradiotherapy from 2009 to 2020. Four independent radiologists (1-20 years' experience) scored MRI studies using a 5-point TRG system (1 = complete response; 5 = no response) based on T2-weighted sequences alone, and then after a 12-week washout period, using a 5-point DWI-TRG system based on T2-weighted and DWI. Scoring confidence was recorded on a 5-point scale (1 = low; 5 = high) for each reading and compared using the Wilcoxon test. Indeterminate scores (TRG-3) from each reading session were compared using the McNemar test. Interobserver agreement was assessed using kappa statistics.

RESULTS

Eighty-five patients were included (mean age, 59 years ± 12 [SD]; 55 women). T2-weighted TRG-3 scores from all readers combined halved from 24% (82/340) to 12% (41/340) with DWI (p < 0.001). TRG-3 scores changed most frequently (41%, 34/82) to DWI-TRG-2 (excellent response). Complete tumour response was recorded clinically in 77/85 patients (91%). Scoring confidence increased using DWI (p < 0.001), with scores of 4 or 5 in 84% (287/340). Interobserver agreement remained fair to moderate (kappa range, 0.28-0.58).

CONCLUSION

DWI complements T2-weighted MRI by reducing the number of indeterminate tumour responses (TRG-3). DWI increases radiologist's scoring confidence.

CLINICAL RELEVANCE STATEMENT

Diffusion-weighted imaging improves T2-weighted tumour response assessment in squamous anal cancer, halving the number of indeterminate responses in the early post treatment period, and increases radiologists' confidence.

KEY POINTS

Tumour response based on T2-weighted MRI is often indeterminate in squamous anal carcinoma. Diffusion-weighted imaging alongside T2-weighted MRI halved indeterminate tumour regression grade scores assigned by four radiologists from 24 to 12%. Scoring confidence of expert and non-expert radiologists increased with the inclusion of diffusion-weighted imaging.

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.

Follow-up imaging of anal cancer after treatment

Anal cancer treatment response assessment can be challenging with both magnetic resonance imaging (MRI) and clinical evaluation considered essential. MRI, in particular, has shown to be useful for the assessment of treatment response, the detection of recurrent disease in follow up and surveillance, and the evaluation of possible post-treatment complications as well as complications from the tumor itself. In this review, we focus on the role of imaging, mainly MRI, in anal cancer treatment response assessment. We also describe the treatment complications that can occur, and the imaging findings associated with those complications.

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.

Anal cancer in Sweden 2015-2019. Implementation of guidelines, structural changes, national registry and early results

BACKGROUND

Squamous cell cancer of the anus is an uncommon malignancy, usually caused by human papilloma virus (HPV). Chemoradiotherapy (CRT) is the recommended treatment in localized disease with cure rates of 60-80%. Local failures should be considered for salvage surgery. With the purpose of improving and equalizing the anal cancer care in Sweden, a number of actions were taken between 2015 and 2017. The aim of this study was to describe the implementation of guidelines and organizational changes and to present early results from the first 5 years of the Swedish anal cancer registry (SACR).

METHODS

The following were implemented: (1) the first national care program with treatment guidelines, (2) standardized care process, (3) centralization of CRT to four centers and salvage surgery to two centers, (4) weekly national multidisciplinary team meetings where all new cases are discussed, (5) the Swedish anal cancer registry (SACR) was started in 2015.

RESULTS

The SACR included 912 patients with a diagnosis of anal cancer from 2015 to 2019, reaching a national coverage of 95%. We could show that guidelines issued in 2017 regarding staging procedures and radiotherapy dose modifications were rapidly implemented. At baseline 52% of patients had lymph node metastases and 9% had distant metastases. Out of all patients in the SACR 89% were treated with curative intent, most of them with CRT, after which 92% achieved a local complete remission and the estimated overall 3-year survival was 85%.

CONCLUSIONS

This is the first report from the SACR, demonstrating rapid nation-wide implementation of guidelines and apparently good treatment outcome in patients with anal cancer in Sweden. The SACR will hopefully be a valuable source for future research.

Treatment of Squamous Cell Carcinoma of the Anus, Unresolved Areas and Future Perspectives for Research: Perspectives of Research Needs in Anal Cancer

Anal cancer is a relatively rare, mostly HPV-related cancer. The curative treatment consists of concurrent chemoradiation delivered with modern radiotherapy techniques. The prognosis for most patients with early localized disease is very favourable; however patients with locally advanced disease and/or HPV negative tumours are at higher risk of locoregional and distant treatment failure. Tailored approaches are presently being investigated to determine the most suitable regimen in terms of radiotherapy dose prescription, target volume selection, normal tissue avoidance, and combination therapy. Metastatic anal cancer is treated with chemotherapy aiming at prolonged survival. The role of immune therapy in the clinical setting is being investigated. There is little knowledge on the biology of anal cancer, and an urgent need for more clinical and translational research dedicated to this disease. In this article, the evidence-base for the current treatment is briefly reviewed, and perspectives on future research needs are high-lighted.

Clinical Practice Guideline: Anal Cancer—Diagnosis, Treatment and Follow-up

BACKGROUND

The number of anal cancer diagnoses has been rising steadily, so that the incidence has doubled in the past 20 years. Almost all anal cancers are induced by persistent infection with human papillomaviruses. Hitherto the care of patients with anal cancer has been heterogeneous and little experience exists with the primary management of anal cancer.

METHODS

The guideline was developed in accordance with the requirements of the German Guideline Program in Oncology. In line with the GRADE approach, the certainty of the evidence was assessed on the outcome level following a systematic literature search. Interdisciplinary working groups were set up to compile suggestions for recommendations, which were discussed and agreed upon in a formal consensus conference.

RESULTS

Ninety-three recommendations and statements were developed. No high-quality evidence was available to support recommendations for or against the treatment of stage I anal cancer with local excision alone as an alternative to chemoradiotherapy. Chemoradiotherapy is the gold standard in the treatment of stages II–III. Among other aspects regarding the timing and extent of response evaluation after chemoradiotherapy, the guideline panel recommended against obtaining a biopsy in the event of complete clinical response. Owing to lack of confidence in the available evidence, only open recommendations were given for treatment of stage IV.

CONCLUSION

This evidence-based clinical practice guideline provides a sound basis for optimizing the interdisciplinary, cross-sector care of anal cancer patients. Among other areas, gaps in research were identified with respect to the care of patients with early-stage or metastatic anal cancer. Approaches such as chemoradiotherapy combined with regional deep hyperthermia require further investigation. The role for immunotherapy in the management of metastasized anal cancer has also been insufficiently explored to date.

Three-dimensional (3D) magnetic resonance volume assessment and loco-regional failure in anal cancer: early evaluation case-control study

Background

The primary aim was to test the hypothesis that deriving pre-treatment 3D magnetic resonance tumour volume (mrTV) quantification improves performance characteristics for the prediction of loco-regional failure compared with standard maximal tumour diameter (1D) assessment in patients with squamous cell carcinoma of the anus undergoing chemoradiotherapy.

Methods

We performed an early evaluation case-control study at two UK centres (2007–2014) in 39 patients with loco-regional failure (cases), and 41 patients disease-free at 3 years (controls). mrTV was determined using the summation of areas method (Vol_sum). Reproducibility was assessed using intraclass concordance correlation (ICC) and Bland-Altman limits of agreements. We derived receiver operating curves using logistic regression models and expressed accuracy as area under the curve (ROC_AUC).

Results

The median time per patient for Vol_sum quantification was 7.00 (inter-quartile range, IQR: 0.57–12.48) minutes. Intra and inter-observer reproducibilities were generally good (ICCs from 0.79 to 0.89) but with wide limits of agreement (intra-observer: − 28 to 31%; inter-observer: − 28 to 46%). Median mrTVs were greater for cases (32.6 IQR: 21.5–53.1 cm³) than controls (9.9 IQR: 5.7–18.1 cm³, p < 0.0001). The ROC_AUC for mrT-size predicting loco-regional failure was 0.74 (95% CI: 0.63–0.85) improving to 0.82 (95% CI: 0.72–0.92) when replaced with mrTV (test for ROC differences, p = 0.024).

Conclusion

Preliminary results suggest that the replacement of mrTV for mrT-size improves prediction of loco-regional failure after chemoradiotherapy for squamous cell carcinoma of the anus. However, mrTV calculation is time consuming and variation in its reproducibility are drawbacks with the current technology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-020-07613-7.

Hellenic society of medical oncology (HESMO) guidelines for the management of anal cancer

Despite considerable improvement in the management of anal cancer, there is a great deal of variation in the outcomes among European countries, and in particular among different hospital centres in Greece and Cyprus. The aim was to elaborate a consensus on the multidisciplinary management of anal cancer, based on European guidelines (European Society of Medical Oncologists-ESMO), considering local special characteristics of our healthcare system. Following discussion and online communication among members of an executive team, a consensus was developed. Guidelines are proposed along with algorithms of diagnosis and treatment. The importance of centralisation, care by a multidisciplinary team (MDT) and adherence to guidelines are emphasised.

Identification of Cancer-Associated Circulating Cells in Anal Cancer Patients

Whilst anal cancer accounts for less than 1% of all new cancer cases, incidence rates have increased by up to 70% in the last 30 years with the majority of cases driven by human papilloma virus (HPV) infection. Standard treatment for localised anal cancer is chemoradiotherapy (CRT). Localised progression is the predominant pattern of relapse but well under 50% of cases are salvaged by surgery, predominantly because confirming recurrence within post-radiation change is very challenging. Identifying cancer-associated circulating cells (CCs) in peripheral blood could offer a corroborative method of monitoring treatment efficacy and identifying relapse early. To study this, nucleated cells were isolated from the blood of patients with anal cancer prior to, during, and after CRT and processed through the Amnis^® ImageStream^®X Mk II Imaging Flow Cytometer, without prior enrichment, using Pan-cytokeratin (PCK), CD45 antibodies and making use of the DNA dye DRAQ5. Analysis was undertaken using IDEAS software to identify those cells that were PCK-positive and DRAQ5-positive as well as CD45-negative; these were designated as CCs. CCs were identified in 7 of 8 patients; range 60-876 cells per mL of blood. This first report of the successful identification of CCs in anal cancer patients raises the possibility that liquid biopsies will find a future role as a prognostic/diagnostic tool in this patient group.

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.

[Rational staging and follow-up of colorectal cancer : Do guidelines provide further help?]

CLINICAL/METHODICAL ISSUE

Colorectal cancer is one of the most common malignant tumors. Preoperative imaging is crucial in rectal cancer as patients can only receive optimal treatment when accurate staging is performed. The N‑staging is often difficult with the available options and must be called into question as a staging parameter.

STANDARD RADIOLOGICAL METHODS

Endoscopic ultrasound (EUS) and magnetic resonance imaging (MRI) are particularly suitable for local staging. Multiparametric MRI with diffusion imaging is indispensable for tumor follow-up.

METHODICAL INNOVATIONS

The assessment of infiltration of the mesorectal fascia is best accomplished using high-resolution MRI. In addition, extramural vascular infiltration (EMVI) has become established as another important prognostic factor. After neoadjuvant therapy and restaging of locally advanced rectal cancer, the identification and validation of prognostically relevant image parameters are prioritized. Multiparametric MRI of the rectum including diffusion imaging as well as the application of radiological and pathological scores (MR-TRG) are becoming increasingly more important in this context.

ASSESSMENT

For the radiologist it is important to become familiar with indicators of the resectability of rectal cancer and to be able to reliably read prognostically relevant imaging parameters in the tumor follow-up.

PRACTICAL RECOMMENDATIONS

For the practical application, the establishment of a fixed MRI protocol is essential. In addition to a guideline-compliant TNM classification, the radiologist must provide the clinician with information on infiltration of the mesorectal fascia and extramural vascular infiltration. The MR-TRGs are becoming increasingly more important in tumor follow-up.

MRI heterogeneity analysis for prediction of recurrence and disease free survival in anal cancer

BACKGROUND

The aim of this study was to evaluate the role of image heterogeneity analysis of standard care magnetic resonance imaging (MRI) in patients with anal squamous cell carcinoma (ASCC) to predict chemoradiotherapy (CRT) outcome. The ability to predict disease recurrence following CRT has the potential to inform personalized radiotherapy approaches currently being explored in novel clinical trials.

METHODS

An IRB waiver was obtained for retrospective analysis of standard care MRIs from ASCC patients presenting between 2010 and 2014. Whole tumor 3D volume-of-interest (VOI) was outlined on T2-weighted (T2w) and diffusion weighted imaging (DWI) of the pre- and post-treatment scans. Independent imaging features most predictive of disease recurrence were added to the baseline clinico-pathological model and the predictive value of respective extended models was calculated using net reclassification improvement (NRI) algorithm. Cross-validation analysis was carried out to determine percentage error reduction with inclusion of imaging features to the baseline model for both endpoints.

RESULTS

Forty patients who underwent 1.5 T pelvic MRI at baseline and following completion of CRT were included. A combination of two baseline MR heterogeneity features (baseline T2w energy and DWI coefficient of variation) was most predictive of disease recurrence resulting in significant NRI (p = 0 < 0.001). This was confirmed in cross-validation analysis with 34.8% percentage error reduction for the primary endpoint and 18.1% reduction for the secondary endpoint with addition of imaging variables to baseline model.

CONCLUSION

MRI heterogeneity analysis offers complementary information, in addition to clinical staging, in predicting outcome of CRT in anal SCC, warranting validation in larger datasets.

Anal squamous cell carcinoma - State of the art management and future perspectives

Anal squamous cell carcinoma (ASCC) is associated with infection with high-risk strains of human papilloma virus (HPV) in 70-90% of cases and a rise in incidence has been observed in the last decades. Definitive chemoradiotherapy (CRT) using 5-fluorouracil and mitomycin C constitutes the standard treatment for localized disease, but about 30% of patients do not respond or relapse locally. Phase I/II trials testing targeted agents, such as epidermal-growth-factor receptor (EGFR) inhibitors, have failed to improve clinical outcome and resulted in increased toxicities. Modern imaging methods and biomarkers, also in the context of HPV status, should be further explored to improve patient stratification. In the present review, we will discuss the current clinical evidence and future perspectives in the management of ASCC. HPV-positive ASCC is more immunogenic with a higher density of tumor infiltrating lymphocytes that correlate with better response to CRT and more favorable prognosis compared to HPV-negative tumors. Immunotherapies including immune checkpoint inhibitors have brought new hope and promising results were recently demonstrated in metastatic ASCC. The addition of immunotherapies to CRT for localized disease is tested in early phase trials, and these results could have a profound impact on the way we treat ASCC in near future. Further research and novel approaches are expected to enhance our understanding of tumor biology and immunology, and improve patient stratification and treatment adaptation in the context of personalized medicine.

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

Although a rare disease, anal cancer is increasingly being diagnosed in patients with risk factors, mainly anal infection with the human papilloma virus. Magnetic resonance imaging (MRI) with external phased-array coils is recommended as the imaging modality of choice to grade anal cancers and to evaluate the response assessment after chemoradiotherapy, with a high contrast and good anatomic resolution of the anal canal. MRI provides a performant evaluation of size, extent and signal characteristics of the anal tumor before and after treatment, as well as lymph node involvement and extension to the adjacent organs. MRI is also particularly helpful in the assessment of complications after treatment, and in the diagnosis for relapse of the diseases.