Anal Cancer: An Examination of Radiotherapy Strategies

PTCOG Gastrointestinal Subcommittee Lower Gastrointestinal Tract Malignancies Consensus Statement

Purpose

Radiotherapy delivery in the definitive management of lower gastrointestinal (LGI) tract malignancies is associated with substantial risk of acute and late gastrointestinal (GI), genitourinary, dermatologic, and hematologic toxicities. Advanced radiation therapy techniques such as proton beam therapy (PBT) offer optimal dosimetric sparing of critical organs at risk, achieving a more favorable therapeutic ratio compared with photon therapy.

Materials and Methods

The international Particle Therapy Cooperative Group GI Subcommittee conducted a systematic literature review, from which consensus recommendations were developed on the application of PBT for LGI malignancies.

Results

Eleven recommendations on clinical indications for which PBT should be considered are presented with supporting literature, and each recommendation was assessed for level of evidence and strength of recommendation. Detailed technical guidelines pertaining to simulation, treatment planning and delivery, and image guidance are also provided.

Conclusion

PBT may be of significant value in select patients with LGI malignancies. Additional clinical data are needed to further elucidate the potential benefits of PBT for patients with anal cancer and rectal cancer.

An integrated model combined intra- and peritumoral regions for predicting chemoradiation response of non small cell lung cancers based on radiomics and deep learning

PURPOSE

The purpose of this study was to develop a model for predicting chemoradiation response in non-small cell lung cancer (NSCLC) patients by integrating radiomics and deep-learning features and combined intra- and peritumoral regions with pre-treated CT images.

MATERIALS AND METHODS

This study enrolled 462 patients with NSCLC who received chemoradiation. On the basis of pretreated CT images, we developed three models to compare the prediction of chemoradiation: intratumoral, peritumoral and combined regions. To further illustrate each model, we established different feature integration methods: a) radiomics model with 1500 features; b) deep learning model with a multiple instance learning algorithm; c) integrated model by integrating radiomic and deep learning features. For radiomics and integrated models, support vector machine and the least absolute shrinkage and selection operator were used to extract and select features. Transfer learning and max pooling algorithms were used to identify high informative features in deep learning models. We applied ten-fold cross validation in model training and testing.

RESULTS

The best area under the curve (AUC) of intratumoral, peritumoral and combined models were 0.89 (95% CI, 0.74-0.93), 0.86 (95% CI, 0.75-0.92) and 0.92 (95% CI, 0.81-0.95), respectively. It indicated the importance of the peritumoral region for treatment response prediction and should be used in combination with the intratumoral region. Integrated models gave better results than models with radiomics and deep learning features alone in all regions of interest and radiomics models outperformed deep learning models in any comparative models.

CONCLUSIONS

The model that integrate radiomic and deep learning features and combined intra- and peritumoral regions provide valuable information in predicting treatment response of chemoradiation. It can help oncologists customize personalized clinical treatment plans for NSCLC patients.

Pencil Beam Scanning (PBS) Intensity-Modulated Proton Therapy (IMPT) Chemoradiotherapy for Anal Canal Cancer-Single Institution Experience

Simple Summary

Eligible patients received PBS IMPT at a single institution. Treatment was administered in two volumes: 1—tumour with margins plus involved lymph nodes; 2—regional lymph node groups: perirectal (mesorectal), obturatory, inguinal, internal, external, and common iliac. The total doses of 57.5 GyE and 45 GyE, respectively, were administered in volumes 1 and 2 in 25 fractions, 5 fractions per week, respectively (a simultaneous integrated boost). Concomitant chemotherapy cisplatinum (CDDP) plus 5-FU or CDDP plus capecitabine was administered as per protocol. This single-institution study showed the high efficacy of PBS IMPT, achieving a high rate of complete regression. The 2-year overall survival, relapse-free survival and colostomy-free survival were 94.2, 93.8 and 91.0%, respectively. The haematological acute toxicity of grade 3–4 remained low. The acute toxicity completely resolved in all patients and had no lethal outcomes.

Abstract

Background: A favourable dose distribution has been described for proton beam therapy (PBT) of anal cancer in dosimetric studies. The relationship between dosimetric parameters in bone marrow and haematologic toxicity, treatment interruptions, and treatment efficacy has also been documented. There are only few references on clinical results of PBT for anal cancer. The primary objective of the retrospective study was to assess the efficacy of pencil beam scanning intensity-modulated proton therapy (PBS IMPT) in the definitive chemoradiotherapy of anal cancer. Secondary objectives were established to identify the risks of acute chronic toxicity risks and to assess colostomy rates. Materials and methods: Patients were treated for biopsy-proven squamous cell cancer (SCC) of the anus at initial or advanced stages. Eligible patients received PBS IMPT at a single institution. Treatment was administered in two volumes: 1—tumour with margins plus involved lymph nodes; 2—regional lymph node groups: perirectal (mesorectal), obturatory, inguinal, internal, external, and common iliac. The total doses of 57.5 GyE and 45 GyE, respectively, were administered in volumes 1 and 2 in 25 fractions, 5 fractions per week, respectively (a simultaneous integrated boost). Concomitant chemotherapy cisplatinum (CDDP) plus 5-FU or CDDP plus capecitabine was administered as per protocol. The treatment effect was assessed using DRE (digital rectal examination) and MRI (magnetic resonance imaging) within the follow-up period. Toxicity was scaled using CTCAE version 4.0 criteria. Results: 39 of 41 patients treated during the period of February 2014–August 2021 were eligible for analysis. All patients completed treatment, 76.9% without interruption. The median treatment time was 35 days (32–35). The median follow-up period was 30 months, 34 patients are alive to-date, 5 patients died prior to the date of analysis, and 2 deaths were unrelated to the primary disease. The 2-year overall survival, relapse-free survival, and colostomy-free survival were 94.2%, 93.8%, and 91.0%, respectively. Complete regression was achieved in 36 patients (92.3%), partial regression was achieved in 2 (5.1%), and immediate progression at end of treatment occurred in 1 patient (2.6%). Salvage resection was indicated for two patients in partial regression and due to severe chronic dermatologic toxicity. The grade 3 and 4 haematological toxicity rates were 7.7% and 5.1%, respectively. The most frequent non-haematological acute toxicities of grade 3–4 observed were dermatitis (23.1%), diarrhoea (7.7%), and dehydration (7.7%). Chronic toxicity emerged predominantly as skin atrophy/ulceration grade 2 (26.5%) and grade 3–4 (5.8%), and radiation proctitis grade 2 (38.2%) and grade 3 (2.9%). Discussion, conclusions: This single-institution study showed the high efficacy of PBS IMPT, achieving a high rate of complete regression. The haematological acute toxicity of grade 3–4 remained low; however, the impact of altered chemotherapy (CDDP instead of mitomycin C) remains unclear. The incidence of other acute toxicities shares similarity with photon therapy investigated in large studies. The acute toxicity completely resolved in all patients, had no lethal outcomes, and never resulted in the necessity for colostomy. By contrast, it was chronic toxicity, skin ulceration, perirectal fistulation, and fibrosis that resulted in salvage surgery and/or the need for a colostomy. A challenging question remains: to what extent can PBT prevent chronic toxicity? Longer follow-up remains necessary.

Comparison of Anal Versus Rectal Staging in the Prognostication of Rectal Squamous Cell Carcinoma: A Population-Based Analysis

BACKGROUND

Rectal squamous cell carcinoma is a rare malignancy with limited data regarding management and prognosis. It is also unknown whether a rectal squamous cell cancer staging system should be based on size, as for anal squamous cell carcinoma, or depth of invasion, as for rectal adenocarcinoma.

OBJECTIVE

The aims of the current study were to determine the optimal management strategy, prognostic factors, and staging system for rectal squamous cell carcinoma.

DESIGN

This was a population-based study.

SETTINGS

The Surveillance, Epidemiology, and End Results database was used to identify patents diagnosed between 1988 and 2013.

PATIENTS

Patients ≥18 years of age undergoing radiation or local excision alone, radiation with local excision, or radiation with radical resection were included. Patients were then staged according to both the American Joint Committee on Cancer classification for rectal adenocarcinoma (American Joint Committee on Cancer-rectum) and anal cancer (American Joint Committee on Cancer-anus).

MAIN OUTCOME MEASURES

The main outcome was 5-year, disease-specific survival.

RESULTS

In both univariate and multivariate survival analyses, the addition of local excision or radical resection to radiation resulted in similar-to-worse outcomes across all of the stages. Among patients staged according to American Joint Committee on Cancer-rectum (n = 1646), although a significant difference in 5-year survival was observed for stage I as compared with higher stages, no difference was noted between stages II and III (80% vs 61% and 62%). However, in the American Joint Committee on Cancer-anus classification (n = 1327), a significant difference was observed across all of the stages (87% vs 72% vs 59%; p < 0.001). In multivariate analysis, the prognostic discrimination based on HRs provided by the American Joint Committee on Cancer-anus was superior to that of the American Joint Committee on Cancer-rectum.

LIMITATIONS

This study was limited by lack of data on chemotherapy and location of positive nodes.

CONCLUSIONS

A treatment approach primarily based on radiation should be considered the optimal management strategy for rectal squamous cell carcinoma. Moreover, a staging system based on size (American Joint Committee on Cancer-anus) rather than on depth of invasion (American Joint Committee on Cancer-rectum) appears to be more accurate in predicting its prognosis. See Video Abstract at http://links.lww.com/DCR/A734.

A National-Level Validation of the New American Joint Committee on Cancer 8th Edition Subclassification of Stage IIA and B Anal Squamous Cell Cancer

INTRODUCTION

The 8th edition of the American Joint Committee on Cancer (AJCC) updated the staging system of anal squamous cell cancer (ASCC) by subdividing stage II into A (T2N0M0) and B (T3N0M0) based on a secondary analysis of the RTOG 98-11 trial. We aimed to validate this new subclassification utilizing two nationally representative databases.

MATERIALS

The National Cancer Database (NCDB) [2004-2014] and the Surveillance, Epidemiology, and End Results (SEER) database [1988-2013] were queried to identify patients with stage II ASCC.

RESULTS

A total of 6651 and 2579 stage IIA (2-5 cm) and 1777 and 641 stage IIB (> 5 cm) patients were identified in the NCDB and SEER databases, respectively. Compared with stage IIB patients, stage IIA patients within the NCDB were more often females with fewer comorbidities. No significant differences were observed between age, race, receipt of chemotherapy and radiation, and mean radiation dose. Demographic, clinical, and pathologic characteristics were comparable between patients in both datasets. The 5-year OS was 72% and 69% for stage IIA versus 57% and 50% for stage IIB in the NCDB and SEER databases, respectively (p < 0.001). After adjustment for available demographic and clinical confounders, stage IIB was significantly associated with worse survival in both cohorts (hazard ratio 1.58 and 2.01, both p < 0.001).

CONCLUSION

This study validates the new AJCC subclassification of stage II anal cancer into A and B based on size (2-5 cm vs. > 5 cm) in the general ASCC population. AJCC stage IIB patients represent a higher risk category that should be targeted with more aggressive/novel therapies.

Anal carcinoma - Survival and recurrence in a large cohort of patients treated according to Nordic guidelines

OBJECTIVE

To evaluate treatment outcome in a large population-based cohort of patients with anal cancer treated according to Nordic guidelines.

MATERIAL

Clinical data were collected on 1266 patients with anal squamous cell carcinoma diagnosed from 2000 to 2007 in Sweden, Norway and Denmark. 886 of the patients received radiotherapy 54-64Gy with or without chemotherapy (5-fluorouracil plus cisplatin or mitomycin) according to different protocols, stratified by tumor stage.

RESULTS

High age, male gender, large primary tumor, lymph node metastases, distant metastases, poor performance status, and non-inclusion into a protocol were all independent factors associated with worse outcome. Among patients treated according to any of the protocols, the 3-year recurrence-free survival ranged from 63% to 76%, with locoregional recurrences in 17% and distant metastases in 11% of patients. The highest rate of inguinal recurrence (11%) was seen in patients with small primary tumors, treated without inguinal irradiation.

CONCLUSIONS

Good treatment efficacy was obtained with Nordic, widely implemented, guidelines for treatment of anal cancer. Inguinal prophylactic irradiation should be recommended also for small primary tumors.

Dose planning objectives in anal canal cancer IMRT: the TROG ANROTAT experience

INTRODUCTION

Intensity modulated radiotherapy (IMRT) is ideal for anal canal cancer (ACC), delivering high doses to irregular tumour volumes whilst minimising dose to surrounding normal tissues. Establishing achievable dose objectives is a challenge. The purpose of this paper was to utilise data collected in the Assessment of New Radiation Oncology Treatments and Technologies (ANROTAT) project to evaluate the feasibility of ACC IMRT dose planning objectives employed in the Australian situation.

METHODS

Ten Australian centres were randomly allocated three data sets from 15 non-identifiable computed tomography data sets representing a range of disease stages and gender. Each data set was planned by two different centres, producing 30 plans. All tumour and organ at risk (OAR) contours, prescription and dose constraint details were provided. Dose-volume histograms (DVHs) for each plan were analysed to evaluate the feasibility of dose planning objectives provided.

RESULTS

All dose planning objectives for the bone marrow (BM) and femoral heads were achieved. Median planned doses exceeded one or more objectives for bowel, external genitalia and bladder. This reached statistical significance for bowel V30 (P = 0.04), V45 (P < 0.001), V50 (P < 0.001), external genitalia V20 (P < 0.001) and bladder V35 (P < 0.001), V40 (P = 0.01). Gender was found to be the only significant factor in the likelihood of achieving the bowel V50 (P = 0.03) and BM V30 constraints (P = 0.04).

CONCLUSION

The dose planning objectives used in the ANROTAT project provide a good starting point for ACC IMRT planning. To facilitate clinical implementation, it is important to prioritise OAR objectives and recognise factors that affect the achievability of these objectives.

Inguinal lymph node recurrence in the untreated groin of patients with anal carcinoma

BACKGROUND

Inguinal lymph node metastasis is predictive of locoregional recurrence and poor overall survival in anal carcinoma. Metachronous lymph node metastasis occurs in 10% of all anal cancer patients, but multiple studies have shown that the benefit of elective irradiation of the groin depends on T-stage, and the toxicity of groin irradiation must not be underestimated.

OBJECTIVE

To analyze the inguinal recurrence rates among patients with anal carcinoma (T1-4, N0-1) who did not receive elective irradiation therapy to the groin and to determine predictors of inguinal recurrence.

DESIGN

Data on 119 patients treated between 1987 and 2005 were retrospectively analyzed. Patients were treated with 3-dimensional radiotherapy. The median dose was 60 Gy. During radiotherapy, 108 patients also received chemotherapy (5-fluorouracil and mitomycin-C).

RESULTS

AJCC staging showed a distribution of 21 T1 (18%), 58 T2 (49%), 27 T3 (23%), 13 T4 (11%), 101 N0 (85%) and 18 N1 (15%) tumors. The median follow up was 65 months (range, 1-240 months). The 5-year inguinal recurrence rate was 0% for T1, 10% for T2, 21% for T3 and 19% for T4 tumors (p = 0.034). T2 tumors of the perianal skin and the anal canal had 5-year inguinal recurrence rates of 12% and 8%, respectively. The 5-year inguinal recurrence rate was 21% for tumors ≥4 cm vs. 2% for tumors <4 cm in size (p = 0.003).

LIMITATIONS

Eleven patients did not receive chemotherapy.

CONCLUSIONS

Elective irradiation of the groin should be considered for local control in patients (N0-N1) with T2 tumors ≥4 cm in size and/or located in the perianal skin, and in all patients with T3 and T4 tumors.

Anal carcinoma: impact of TN category of disease on survival, disease relapse, and colostomy failure in US Gastrointestinal Intergroup RTOG 98-11 phase 3 trial

PURPOSE

The long-term update of US GI Intergroup RTOG 98-11 anal cancer trial found that concurrent chemoradiation (CCRT) with fluorouracil (5-FU) plus mitomycin had a significant impact on disease-free survival (DFS) and overall survival (OS) compared with induction plus concurrent 5-FU plus cisplatin. The intent of the current analysis was to determine the impact of tumor node (TN) category of disease on survival (DFS and OS), colostomy failure (CF), and relapse (local-regional failure [LRF] and distant metastases [DM]) in this patient group.

METHODS AND MATERIALS

DFS and OS were estimated univariately by using the Kaplan-Meier method, and 6 TN categories were compared by the log-rank test (T2N0, T3N0, T4N0, T2N1-3, T3N1-3, and T4N1-3). Time to relapse and colostomy were estimated by the cumulative incidence method, and TN categories were compared using Gray's test.

RESULTS

Of 682 patients, 620 were analyzable for outcomes by TN category. All endpoints showed statistically significant differences among the TN categories of disease (OS, P<.0001; DFS, P<.0001; LRF, P<.0001; DM, P=.0011; CF, P=.01). Patients with the poorest OS, DFS, and LRF outcomes were those with T3-4N-positive (+) disease. CF was lowest for T2N0 and T2N+ (11%, 11%, respectively) and worst for the T4N0, T3N+, and T4N+ categories (26%, 27%, 24%, respectively).

CONCLUSIONS

TN category of disease has a statistically significant impact on OS, DFS, LRF, DM, and CF in patients treated with CCRT and provides excellent prognostic information for outcomes in patients with anal carcinoma. Significant challenges remain for patients with T4N0 and T3-4N+ categories of disease with regard to survival, relapse, and CF and lesser challenges for T2-3N0/T2N+ categories.