Organ sparing by conformal avoidance intensity-modulated radiation therapy for anal cancer: dosimetric evaluation of coverage of pelvis and inguinal/femoral nodes

Radiation boost for synchronous solitary inguinal lymph node metastasis during neoadjuvant chemoradiotherapy for locally advanced rectal cancer

BACKGROUND

Some patients with locally advanced rectal cancer (LARC) present with inguinal lymph node metastases without evidence of other systemic disease, known as solitary inguinal lymph node metastasis (SILNM). These patients may represent a distinct subset who have a more favorable prognosis and should be treated with curative intent. The optimal treatment strategy for these patients has not been determined.

METHODS

We retrospectively reviewed 16 consecutive LARC patients diagnosed between January 2017 and December 2019, who had SILNM, were treated with an inguinal lymph nodes (ILN) radiation boost with curative intent during neoadjuvant chemoradiotherapy (nCRT) and underwent total mesorectal excision (TME). We used Kaplan-Meier survival curves to calculate survival rates, and recorded radiation-related toxicity.

RESULTS

None of these 16 patients developed pelvic or inguinal recurrences, and 3 of the patients developed distant metastases. The 3-year overall survival rate and locoregional relapse-free survival rate were both 100%. The 3-year disease-free rate and distant metastasis-free survival rate were both 81.3%. Of 5 patients who had ILN dissection for suspicious ILNs after neoadjuvant treatment, 2 had residual nodal tumor confirmed. Grade 3 toxicity was found in 5 patients, and no patients had lymphedema or other grade 4 or 5 toxicities.

CONCLUSIONS

In LARC patients with synchronous SILNM, a radiation boost to the ILNs during nCRT achieved excellent local control with acceptable toxicity. Though the optimal treatment strategy remains unclear, nCRT with an ILN radiation boost prior to TME may be a reasonable therapeutic approach to consider for this subset of patients.

Practice of radiation therapy for anal cancer in Austria-a survey on behalf of the Austrian radiation oncology society gastrointestinal tumor group (ÖGRO-GIT)

Purpose

We conducted a patterns-of-care survey on chemoradiation for locoregionally confined anal cancer in Austria to evaluate areas of disagreement and to identify possible targets for further standardization.

Methods

An anonymous questionnaire comprising 38 questions was sent to all Austrian radiation oncology departments. Results were analyzed descriptively and compared to two international guidelines.

Results

The response rate was 93%. Work-up generally includes DRE, endoscopy, and cross-sectional imaging of chest/abdomen and pelvis. PET-CT is used by 38%. Screening for HIV and biopsies of suspicious lymph nodes are infrequently used. All centers perform IMRT, mainly with daily IGRT. Median doses to the primary are 54.7 Gy (T1–2) and 59.4 Gy (T3–4). Suspicious nodes receive a boost (median dose 54 Gy), while elective nodal areas are mainly treated with 45–50.4 Gy. Target delineation of elective nodal areas seems generally uniform, although disagreement exists regarding inclusion of the common iliac nodes. No agreement was found for OAR-delineation and dose constraints. Concurrent chemotherapy is mitomycin and 5‑FU/capecitabine. Supportive care beyond skin care is infrequently offered. Intensive follow-up is performed for at least 5 years. Treatment of T1N0 shows considerable disagreement.

Conclusion

We found a high rate of agreement between the centers and concordance with major guidelines. PET-CT, routine HIV testing, and biopsies of suspicious LN seem underrepresented. The largest controversy regarding target volumes concerns inclusion of the common iliac nodes. Prescribed doses are generally in line with the recommendations or higher. OAR delineation, dose constraints, supportive care, and treatment of early anal cancer represent areas for further standardization.

Supplementary Information

The online version of this article (10.1007/s00066-021-01842-w) contains supplementary material, which is available to authorized users.

Intensity modulated radiotherapy in anal canal squamous cell carcinoma: Implementation and outcomes

Objective

Concurrent chemoradiotherapy (CCRT) is the standard curative treatment option for nonmetastatic anal squamous cell carcinoma (SCC). Intensity modulated radiotherapy (IMRT) can reduce doses delivered to bowel and skin and reduce toxicities associated with conventional fields. Here, we present our institutional data on dosimetry, toxicity, and clinical outcomes with IMRT for anal cancer.

Materials and Methods

We analyzed 23 patients of anal SCC treated with curative-intent CCRT/radiation therapy alone, utilizing IMRT, between August 2011 and December 2016. The standard prescription dose was 54 Gy/27Fr/5.5 weeks, delivered in two phases, and concurrent chemotherapy with 5-fluorouracil and mitomycin-C. Acute and late toxicities and dosimetric data were compiled and analyzed.

Results

The median age was 65 years. Fourteen (60.7%) patients had Stage IIIC disease. Eighteen patients received concurrent chemotherapy. No patient had any treatment breaks. Grade 3 acute perianal dermatitis was recorded in 11 (47.8%) patients. Proctitis, diarrhea, and cystitis were limited to Grade 1 in 73.9%, 47.8%, and 8.6% patients, respectively. The only late Grade 2+ toxicities were gastrointestinal toxicities in 4 (17.4%) patients. Twenty (87%) patients had complete response at 6 months. The 3-year local control, nodal control, and distant metastases-free survival were 85.9%, 86.6%, 84.7%, respectively, with 3-year disease-free survival and overall survival of 63.4% and 81%, respectively.

Conclusion

In this report on IMRT in anal cancer from India, treatment was well tolerated with lower acute toxicity than reported in other prospective studies. Long-term results are at par with other published studies.

Dosimetric comparison of volumetric modulated arc therapy and intensity modulated radiation therapy for anal cancer

Aim:

Volumetric modulated arc therapy (VMAT), an extension of intensity modulated radiation therapy (IMRT), employs modifications in gantry rotation speed, machine dose rate and multi-leaf collimator motion to deliver a three-dimensional dose distribution. This study compared VMAT to IMRT for patients with anal carcinoma.

Materials and Methods:

Sixteen patients previously treated with IMRT were retrospectively selected. Each patient received a total dose of 57·6–63·0 Gy in 1·8 Gy fractions. A single- or double-isocenter multi-arc VMAT treatment plan was generated using Eclipse RapidArc system with the same computed tomography image sets and optimisation constraints used for IMRT. Dose–volume histograms (DVHs) for planning target volumes (PTVs) and organs at risk (OARs), and monitor units (MUs) and beam on times (BOTs) were used for comparison.

Results:

IMRT and VMAT plans showed insignificant differences in PTV homogeneity and conformity and sparing hips and bowel. VMAT required fewer mean MU and shorter BOT per plan (1,597 MU, 2·66 min) compared to IMRT (2,571 MU, 4·29 min) with p < 0·0001.

Conclusions:

Fewer MU and shorter BOT for VMAT may decrease the damage from secondary radiation and treatment delivery uncertainty due to intra-fraction tumour motion, leading to higher machine throughput and improving patient comfort, with less treatment time.

Anal Cancer in the Era of Dose Painted Intensity Modulated Radiation Therapy: Implications for Regional Nodal Therapy

Since the initial development of 5-fluorouracil and mitomycin as a standard of care platform for definitive anal cancer chemoradiotherapy, multiple studies have evaluated the optimal chemotherapy regimen, and radiotherapy technique. Refinements in treatment technique have taken place during an era of improved diagnostic imaging, including incorporation of FDG-PET, with implications for a possible stage migration effect. This has introduced an opportunity to develop stage-specific recommendations for primary tumor, involved nodal, and elective nodal irradiation dose. Elective nodal irradiation remains standard given the low rates of elective nodal failure with current practice, although may be subject to evolving controversy for patients with early stage disease. In this review, development of the current standard of care for anal cancer chemoradiotherapy is reviewed in the context of modern staging and dose-painted radiotherapy treatment techniques.

Toxicity and survival of anal cancer patients treated with intensity-modulated radiation therapy

INTRODUCTION

The definitive treatment of anal cancer with chemoradiotherapy spares abdominoperineal resection for salvage treatment but carries a high burden of toxicity. Intensity-modulated radiation therapy has been implemented to reduce toxicity, reduce treatment breaks and improve survival. However, large and long-term studies are lacking. We aimed to investigate the toxicities and long-term survival of anal cancer patients treated with intensity-modulated radiation therapy at James Cook University Hospital, Middlesbrough.

MATERIALS AND METHODS

We conducted a retrospective analysis of all patients with squamous cell anal cancer treated at James Cook University Hospital between July 2010 and April 2017. All patients were uniformly treated with intensity-modulated radiation therapy-based chemoradiation with curative intent. A subset of these patients was followed-up prospectively by an oncologist for acute and late toxicity. We calculated Kaplan-Meier estimates of survival statistics and compared our results with those of previous trials which used conventional radiotherapy.

RESULTS

We studied 132 patients, including a toxicity subset of 64, for a median follow-up time of 43 months (range 3-84 months). Eleven patients (8.3%) underwent salvage abdominoperineal resection. Grade 3+ acute non-haematological, gastrointestinal, genitourinary and dermatological toxicity were found in 56.2%, 12.3%, 0% and 50.7% of the toxicity subset (n = 64). Median treatment duration was 37 days. Overall and colostomy-free survival at five years were 68.3% and 85.3%, respectively. Tumour size (P = 0.006) and age (P = 0.002) predicted shorter overall survival.

CONCLUSIONS

Intensity-modulated radiation therapy probably reduces acute gastrointestinal and genitourinary toxicity compared with conventional radiotherapy, while resulting in similar overall and colostomy-free survival. We suggest that further dose escalation may improve survival in patients with T3/T4 tumours.

Management of locally advanced anal canal carcinoma with intensity-modulated radiotherapy and concurrent chemotherapy

The best curative option for locally advanced (stages II-III) squamous-cell carcinomas of the anal canal (SCCAC) is concurrent chemo-radiotherapy delivering 36-45 Gy to the prophylactic planning target volume with an additional boost of 14-20 Gy to the gross tumor volume with or without a gap-period between these two sequences. Although 3-dimensional conformal radiotherapy led to suboptimal tumor coverage because of field junctions, this modality remains a standard of care. Recently, intensity-modulated radiotherapy (IMRT) techniques improved tumor coverage while decreasing doses delivered to organs at risk. Sparing healthy tissues results in fewer severe acute toxicities. Consequently, IMRT could potentially avoid a gap-period that may increase the risk of local failure. Furthermore, these modalities reduce severe late toxicities of the gastrointestinal tract as well as better functional conservation of anorectal sphincter. This report aims to critically review contemporary trends in the management of locally advanced SCCAC using IMRT and concurrent chemotherapy.

Impact of intensity modulated radiation therapy on survival in anal cancer

Background

This study was designed to investigate the impact of intensity modulated radiation therapy (IMRT) on overall survival (OS) in patients treated with chemoradiation (CRT) for anal cancer (AC).

Methods

We performed a case-control, propensity score (PS) matched analysis of the National Cancer Data Base (NCDB) of patients diagnosed with non-metastatic AC from 2004 to 2013. Only patients receiving concurrent CRT were included. Patients were stratified into two groups based on the RT technique: IMRT vs. non-IMRT. Multivariate analysis (MVA) and Kaplan-Meier (KM) plots for OS were obtained for the matched and unmatched groups.

Results

A total of 8,108 patients diagnosed between 2004 and 2013 were eligible for the study, of which 3,307 (40.8%) and 4,801 (59.2%) were in the IMRT and non-IMRT groups, respectively. Median follow-up for all patients was 54.4 months. After PS matching, MVA for OS showed that IMRT was associated with improved OS compared to non-IMRT (HR 0.83, 95% CI: 0.74-0.94; P=0.002). Adjusted KM analysis showed that the 5-year OS for patients treated with IMRT was 74.6% vs. 70.5% (P=0.0022).

Conclusions

To our knowledge, this is the largest study to date that evaluates the impact of IMRT on OS for patients with AC. Our investigation shows that IMRT based concurrent CRT for non-metastatic AC is associated with improved survival when compared to similar patients treated with non-IMRT based therapy. In the absence of randomized evidence, our analysis might provide additional support for increasing the use of IMRT for patients with AC receiving concurrent CRT.

Utilization of intensity modulated radiation therapy for anal cancer in the United States

Background

Chemoradiotherapy for anal cancer (AC) can incur substantial treatment-related toxicities. Whereas radiotherapy (RT) for AC has historically been delivered with two- or three-dimensional conformal RT (2D/3DCRT) techniques, intensity-modulated RT (IMRT) is associated with improved target conformality and lower doses to organs-at-risk (OARs). This is the first investigation to date evaluating trends of IMRT utilization in the United States.

Methods

The National Cancer Data Base (NCDB) was queried [2004-2015] for AC patients receiving definitive chemoradiotherapy with a defined RT technique (3DCRT versus IMRT). Following analysis based on temporal trends, multivariate logistic regression determined factors associated with receipt of IMRT. Secondarily, Kaplan-Meier analysis compared OS between the 3DCRT and IMRT groups, and Cox proportional hazards modeling determined variables associated with OS.

Results

Altogether, 11,396 patients met study criteria; 1,288 (11%) were treated with 3DCRT and 10,108 (89%) with IMRT. Temporally, utilization of IMRT rose significantly, from 28% in 2004 to 96% in 2015, corresponding with a progressive decrease in 3DCRT usage. IMRT was more likely delivered in node-positive disease, at academic centers, and in southern/western regions (P<0.05 for all). T3-4 disease was less likely to receive IMRT (P<0.05). As expected, there were no OS differences based on RT technique (P=0.402). Predictors of worse OS included advancing age, male gender, increasing comorbidities, advanced T-stage, and nodal positivity (P<0.05 for all). In addition to racial- and insurance-related factors, receipt of therapy at academic centers independently predicted for improved OS (P<0.05 for all).

Conclusions

Based on findings from this large, contemporary dataset, IMRT is now the most widely utilized RT technique for AC, and 3DCRT is used in a very small minority of patients. IMRT utilization is impacted by multiple characteristics, such as disease- and regional-related factors. These observations have implications for payers and insurance coverage; improved survival at academic centers has ramifications for patient counseling.

Modern intensity-modulated radiotherapy with image guidance allows low toxicity rates and good local control in chemoradiotherapy for anal cancer patients

PURPOSE

To report outcomes of a population of anal cancer patients treated with modern intensity-modulated radiotherapy and daily image-guided radiotherapy techniques.

METHODS

We analyzed data of 155 patients consecutively treated with intensity-modulated radiotherapy +/- chemotherapy in three radiotherapy departments. One hundred twenty-two patients presented a stage II-IIIA disease. Chemotherapy was administered in 138 patients, mainly using mitomycin C and 5-fluorouracil (n = 81). All patients received 36 Gy (1.8 Gy/fraction) on the pelvic and inguinal nodes, on the rectum, on the mesorectum and on the anal canal, and a sequential boost up to a total dose of 59.4 Gy (1.8 Gy/fraction) on the anal canal and on the nodal gross tumor volumes.

RESULTS

Median follow-up was 38 months (interquartile range 12-51). Toxicity data were available for 143 patients: 22% of them presented a G3+ acute toxicity, mainly as moist desquamation (n = 25 patients) or diarrhea (n = 10). Three patients presented a late grade 3 gastrointestinal toxicity (anal incontinence). No grade 4 acute or late toxicity was recorded. Patients treated with fixed-gantry IMRT delivered with a sliding window technique presented a significantly higher risk of acute grade 3 (or more) toxicity compared to those treated with VMAT or helical tomotherapy (38.5 vs 15.3%, p = 0.049). Actuarial 4-year local control rate was 82% (95% CI 76-91%).

CONCLUSIONS

Modern intensity-modulated radiotherapy with daily image-guided radiotherapy is effective and safe in treating anal cancer patients and should be considered the standard of care in this clinical setting.

Dosimetric advantages and clinical outcomes of simultaneous integrated boost intensity-modulated radiotherapy for anal squamous cell carcinoma

Purpose

The purpose of this study was to explore the dosimetric difference between simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) and three-dimensional conformal radiotherapy (3DCRT), and the clinical outcomes of anal squamous cell carcinoma (ASCC) chemoradiotherapy featuring SIB-IMRT.

Materials and Methods

This study included ten patients with ASCC who underwent chemoradiotherapy using SIB-IMRT with 5-fluorouracil and mitomycin C. SIB-IMRT delivered 54 Gy to each primary tumor plus metastatic lymph nodes and 45 Gy to regional lymph nodes, in 30 fractions. Four patients received additional boosts to the primary tumors and metastatic lymph nodes; the median total dose was 54 Gy (range, 54 to 60 Gy). We additionally created 3DCRT plans following the Radiation Therapy Oncology Group 9811 protocol to allow dosimetric comparisons with SIB-IMRT. Locoregional control, overall survival, and toxicity were calculated for the clinical outcome evaluation.

Results

Compared to 3DCRT, SIB-IMRT significantly reduced doses to the external genitalia, bladder, and intestine, delivering the doses to target and elective nodal region. At a median follow-up time of 46 months, 3-year locoregional control and overall survival rates were 88.9% and 100%, respectively. Acute toxicities were treated conservatively. All patients completed radiotherapy with brief interruptions (range, 0 to 2 days). No patient experienced ≥grade 3 late toxicity during the follow-up period.

Conclusion

The dosimetric advantages of SIB-IMRT appeared to reduce the toxicity of chemoradiotherapy for ASCC achieving high locoregional control in the extended period.

Radiotherapy for Anal Cancer: Intensity-Modulated Radiotherapy and Future Directions

The treatment of anal cancer has evolved remarkably in the past 30 years. Definitive chemoradiotherapy is the standard of care, allowing organ preservation and maintenance of continence for most patients. This article reviews recent advances in radiotherapy planning and delivery that have resulted in improvements in treatment-related toxicity. Most notably, the advent and wide adoption of intensity-modulated radiotherapy provides a superior toxicity profile compared with older techniques, while maintaining similar oncologic outcomes. Current areas of active research include optimizing and individualizing treatment intensity and possible integration of biologic agents and immunotherapies in the treatment of anal cancer.

Early dose-dependent cortical thinning of the femoral neck in anal cancer patients treated with pelvic radiation therapy

BACKGROUND AND PURPOSE

Anal cancer patients treated with radiation therapy (RT) have an increased risk of hip fractures after treatment. The mechanism of these fractures is unknown; however, femoral fractures have been correlated with cortical bone thinning. The objective of this study was to assess early changes in cortical bone thickness at common sites of femoral fracture in anal cancer patients treated with intensity modulated radiation therapy (IMRT).

MATERIALS AND METHODS

RT treatment plans and computed tomography (CT) scans from 23 anal cancer patients who underwent IMRT between November 2012 and December 2014 were retrospectively reviewed. Cortical thickness (Ct.Th) was mapped at homologous vertices within the proximal femur using pre-RT and post-RT (≤4months) CT scans. The bone attenuation measurements were collected at homologous locations within the trabecular bone of the right femoral neck (FN). The percent change in Ct.Th and trabecular bone mineral density (trBMD) were assessed. FN cortical thinning was correlated to RT dose using linear regression. A logistic model for dose dependent cortical thinning was constructed.

RESULTS

Twenty-two patients were analyzed. Significant post-treatment cortical thinning was observed in the intertrochanteric crest, subcapital and inferior FN (p<0.05). FN volume receiving ≥40Gy (V40Gy) was a significant predictor of focal cortical thinning ≥30% (p=0.03). A significant decrease in FN trBMD was observed (-6.4% [range -34.4 to 3.3%]; p=0.01).

CONCLUSION

Significant early decrease in Ct.Th and trBMD occurs at the FN in patients treated with RT for anal cancer. FN V40Gy was predictive of clinically significant focal FN cortical thinning.

Genital invasion or perigenital spread may pose a risk of marginal misses for Intensity Modulated Radiotherapy (IMRT) in anal cancer

BACKGROUND

While intensity modulated radiotherapy (IMRT) in anal cancer is feasible and improves high-dose conformality, the current RTOG/AGITG contouring atlas and planning guidelines lack specific instructions on how to proceed with external genitalia. Meanwhile, the RTOG-Protocol 0529 explicitly recommends genital sparing on the basis of specific genital dose constraints. Recent pattern-of-relapse studies based on conventional techniques suggest that marginal miss might be a potential consequence of genital sparing. Our goal is to outline the potential scope and increase the awareness for this clinical issue.

METHODS

We present and discuss four patients with perigenital spread in anal cancer in both early and advanced stages (three at time of first diagnosis and one in form of relapse). Genital/perigenital spread was observed once as direct genital infiltration and thrice in form of perigenital lymphatic spread.

RESULTS

We review the available data regarding the potential consequences of genital sparing in anal cancer. Pattern-of-relapse studies in anal cancer after conventional radiotherapy and the current use of IMRT in anal cancer are equivocal but suggest that genital sparing may occasionally result in marginal miss. An obvious hypothesis suggested by our report is that perigenital lymphovascular invasion might be associated with manifest inguinal N+ disease.

CONCLUSIONS

Local failure has low salvage rates in recent anal cancer treatment series. Perigenital spread may pose a risk of marginal misses in IMRT in anal cancer. To prevent marginal misses, meticulous pattern-of-relapse analyses of controlled IMRT-series are warranted. Until their publication, genital sparing should be applied with caution, PET/CT should be used when possible and meeting genital dose constraints should not be prioritized over CTV coverage, especially (but not only) in stage T3/4 and N+ disease.

Squamous-cell carcinoma of the anus: progress in radiotherapy treatment

Chemoradiotherapy is the standard-of-care treatment of squamous-cell carcinoma of the anus (SCCA), and this has not changed in decades. Radiation doses of 50-60 Gy, as used in many phase III trials, result in substantial late morbidities and fail to control larger and node-positive tumours. Technological advances in radiation therapy are improving patient outcomes and quality of life, and should be applied to patients with SCCA. Modern techniques such as intensity-modulated radiotherapy (IMRT), rotational IMRT, image-guided radiotherapy using cone-beam CT, and stereotactic techniques have enabled smaller margins and highly conformal plans, resulting in decreased radiation doses to the organs at risk and ensuring a shorter overall treatment time. In this Perspectives article, the use of novel approaches to target delineation, optimized radiotherapy techniques, adaptive radiotherapy, dose-escalation with external-beam radiotherapy (EBRT) or brachytherapy, and the potential for modified fractionation are discussed in the context of SCCA.

Helical Tomotherapy for the Treatment of Anal Canal Cancer: A Dosimetric Comparison with 3D Conformal Radiotherapy

Aims and Background

The standard treatment of anal canal cancer (ACC) is combined chemotherapy and radiation therapy (RT), which is complex because of the shape of the target volumes and the need to minimize the irradiation of normal pelvic structures. In this study we compared the dosimetric results of helical tomotherapy (HT) plans with traditional 3D conformal RT (3DRT) plans for the treatment of ACC.

Methods and Study Design

Twelve patients (median age 57 years, range 38–83; F/M 8/4) treated with HT and concurrent chemotherapy for locally advanced ACC were selected. All had histologically confirmed squamous-cell carcinoma. A clinical target volume including the tumor and pelvic and inguinal lymph nodes was treated with HT to a total dose of 36 Gy in 1.8-Gy daily fractions. Then a sequential boost of 23.4 Gy in 1.8-Gy daily fractions (total dose 59.4 Gy) was delivered to the tumor and involved nodes. For all 12 patients, 3DRT plans were generated for comparison. Treatment plans were evaluated by means of standard dose-volume histograms. Dose coverage of the planning target volumes (PTVs), homogeneity index (HI), and mean doses to organs at risk (OARs) were compared.

Results

The coverage of PTV was comparable between the two treatment plans. HI was better in the HT vs. 3DRT plans (1.25 and 3.57, respectively; p<0.0001). HT plans resulted in better sparing of OARs (p<0.0001).

Conclusions

HT showed superior target dose conformality and significant sparing of pelvic structures compared with 3DRT. Further investigation should determine if these dosimetric improvements will improve clinical outcomes regarding locoregional control, survival, and treatment-related acute and late morbidity.

Pencil-beam scanning proton therapy for anal cancer: a dosimetric comparison with intensity-modulated radiotherapy

BACKGROUND

Concurrent chemoradiotherapy cures most patients with anal squamous cell carcinoma at the cost of significant treatment-related toxicities. Intensity-modulated radiotherapy (IMRT) reduces side effects compared to older techniques, but whether proton beam therapy (PBT) offers additional advantages is unclear.

MATERIAL AND METHODS

Eight patients treated with PBT for anal cancer were chosen for this study. We conducted detailed plan comparisons between pencil-beam scanning PBT via two posterior oblique fields and seven-field IMRT. Cumulative dose-volume histograms were analyzed by Wilcoxon signed-rank test, and plan delivery robustness was assessed via verification computed tomography (CT) scans obtained during treatment.

RESULTS

Compared to IMRT, PBT reduced low dose radiation (≤ 30 Gy) to the small bowel, total pelvic bone marrow, external genitalia, femoral heads, and bladder (all p < 0.05) without compromising target coverage. For PBT versus IMRT, mean small bowel volume receiving ≥ 15 Gy (V15) was 81 versus 151 cm(3), mean external genitalia V20 was 14 versus 40%, and mean total pelvic bone marrow V15 was 66 versus 83% (all p = 0.008). The lumbosacral bone marrow dose was higher with PBT due to beam geometry. PBT was delivered with ≤ 1.3% interfraction deviation in the dose received by 98% of the clinical target volumes.

CONCLUSION

Pencil-beam scanning PBT is clinically feasible and can be robustly delivered for anal cancer patients. Compared with IMRT, PBT reduces low dose radiation to important organs at risk in this population. While the clinical benefit of these differences remains to be shown, existing data suggest that limiting low dose to the small bowel and pelvic bone marrow may reduce treatment toxicity.

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.

Acute small-bowel toxicity during neoadjuvant combined radiochemotherapy in locally advanced rectal cancer: determination of optimal dose-volume cut-off value predicting grade 2-3 diarrhoea

Background

Current therapeutic standard for locally advanced rectal cancer is the neoadjuvant radiochemotherapy with total mesorectal excision. Diarrhoea is the main acute side effect, induced by the dose to the small-bowel, frequently leading to a treatment modification. Aim of this study was to analyse the differences between the irradiated small-bowel volumes and the occurrence of acute diarrhea during combined radiochemotherapy for rectal cancer.

Methods

45 patients treated with a neoadjuvant radiochemotherapy (three-field box 50.4 Gy; Cetuximab, Capecitabine, Irinotecan) for locally advanced rectal cancer within a prospective phase I/II study were evaluated. Based on the dose-volume histograms, the small-bowel volumes receiving doses of 5, 10 … 45 Gy (V5, V10 …V45) were calculated and compared with the prospectively documented small- bowel toxicities.

Results

There was a statistically significant difference between irradiated small-bowel volumes and the severity of therapy related diarrhoea. The strongest validity concerning the risk of developing a grade 2–3 diarrhoea was seen at a dose level of 5 Gy (V 5) with a small-bowel volume of 291.94 cc. Patients with V 5 > 291.94 cc had significantly more often grade 2–3 diarrhoea, than patients with V5 below this cut-off value (82% vs. 29%; p < 0.0001).

Conclusions

In the inverse treatment planning of rectal caner patients the small-bowel volume receiving 5 Gy should be limited to about 300 cc.

Intensity-modulated radiation therapy with concurrent chemotherapy for anal cancer: outcomes and toxicity

OBJECTIVES

To evaluate toxicity, local control, and survival in anal cancer patients treated with intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy.

METHODS

Sixty-five patients were treated at a single institution with IMRT and concurrent chemotherapy for localized squamous cell carcinoma of the anal canal. Radiotherapy was delivered with a simultaneous integrated boost technique, with dose based on the T stage. The median dose to the primary tumor and pelvis were 54 Gy (range, 50 to 58.8 Gy) and 45 Gy (range, 40.5 to 50.4 Gy), respectively. The most common concurrent chemotherapy regimens were 5-fluorouracil and cisplatin (75%), capecitabine and oxaliplatin (11%), and 5-fluorouracil and mitomycin C (5%).

RESULTS

The percentage of patients with Tx, T1, T2, T3, and T4 disease were 8%, 17%, 49%, 15%, and 11%, respectively. The percentage of patients with N0, N1, N2, and N3 disease were 46%, 17%, 9%, and 28%, respectively. Ninety-one percent of patients completed treatment without a break. Grade 3 gastrointestinal toxicity occurred in 9%, and moist desquamation beyond the perianal area occurred in 17%. The use of a vaginal dilator during simulation and treatment seemed to lower the rates of acute skin and late sexual toxicity. With a median follow-up of 19 months, the 2-year local and distant control rates were both 93%. The 2-year overall and disease-free survival rates were 96% and 86%, respectively.

CONCLUSIONS

Concurrent chemotherapy and IMRT was well tolerated, and was associated with low rates of acute and late toxicity and excellent local control, disease-free survival, and overall survival.

Chemoradiotherapy for anal cancer: clinical trials past, present and future

SUMMARY

Anal cancer is a rare cancer whose incidence is increasing in the UK. It is associated with human papilloma virus infection and smoking and is more common in women and immunosuppressed individuals, including those with transplants and HIV infection. The current standard of care is chemoradiotherapy (CRT) to the pelvis with surgery reserved for patients where CRT is contraindicated or as salvage treatment for residual disease or recurrence post-CRT. Radiotherapy combined with mitomycin-C and 5-fluorouracil has emerged as the standard of care following a series of six well-conducted Phase III trials. Trials have shown no benefit for cisplatin-based combination regimens either concurrently, adjuvantly or neoadjuvantly.

Predictive factors for early and late local toxicities in anal cancer treated by radiotherapy in combination with or without chemotherapy

BACKGROUND

The treatment of anal cancer is based on concomitant radiotherapy and chemotherapy and is associated with a nonnegligible rate of local severe toxicities that can strongly impair the quality of life.

OBJECTIVE

A retrospective analysis was performed to screen the following factors as potential predictive factors for local skin and digestive toxicities, and as potential prognostic factors for cumulative colostomy incidence: sex, age, tumor size, clinical T and N stage, circumferential extension, invasion of anal margin, HIV status, type of chemotherapy, and type of radiotherapy and dose delivered.

METHODS

One hundred five patients in our database treated between January 2000 and February 2010 met the eligibility criteria.

RESULTS

Median follow-up was 54.1 months (range, 1-133). Early and late severe local toxicities occurred in 33 patients (31.4%) and 18 patients (17.1%). The 5-year cumulative rate of colostomy was 26.6%. Predictive factors for local severe early toxicities were as follows: clinical stage III/IV (p = 0.01), no brachytherapy boost (p = 0.003), and use of chemotherapy (p = 0.01). Only brachytherapy retained its independence in multivariate analysis (OR = 4.8 (1.4-16.3), p = 0.01). Human immunodeficiency virus positivity (p = 0.04) was the only predictive factor for late toxicities in univariate analysis; it was linked independently to the occurrence of ulcer (OR = 0.1 (0.01-0.66), p = 0.01). Tumor size ≥4 cm (p < 0.001) and occurrence of grade 2 to 3 ulcers (p < 0.001) were correlated with greater cumulative colostomy incidence.

CONCLUSIONS

In this cohort, nonuse of brachytherapy was an independent predictive factor for local acute toxicity. Human immunodeficiency virus positivity was the only predictive factor for local late toxicities and strongly influenced the onset of ulcer.

Dosimetric impact of inter-observer variability for 3D conformal radiotherapy and volumetric modulated arc therapy: the rectal tumor target definition case

Background

To assess the dosimetric effect induced by inter-observer variability in target definition for 3D-conformal RT (3DCRT) and volumetric modulated arc therapy by RapidArc (RA) techniques for rectal cancer treatment.

Methods

Ten patients with rectal cancer subjected to neo-adjuvant RT were randomly selected from the internal database. Four radiation oncologists independently contoured the clinical target volume (CTV) in blind mode. Planning target volume (PTV) was defined as CTV + 7 mm in the three directions. Afterwards, shared guidelines between radiation oncologists were introduced to give general criteria for the contouring of rectal target and the four radiation oncologists defined new CTV following the guidelines. For each patient, six intersections (I) and unions (U) volumes were calculated coupling the contours of the various oncologists. This was repeated for the contours drawn after the guidelines. Agreement Index (AI = I/U) was calculated pre and post guidelines. Two RT plans (one with 3DCRT technique using 3–4 fields and one with RA using a single modulated arc) were optimized on each radiation oncologist’s PTV. For each plan the PTV volume receiving at least 95% of the prescribed dose (PTV V95%) was calculated for both target and non-target PTVs.

Results

The inter-operator AI pre-guidelines was 0.57 and was increased up to 0.69 post-guidelines. The maximum volume difference between the various CTV couples, drawn for each patient, passed from 380 ± 147 cm³ to 137 ± 83 cm³ after the introduction of guidelines. The mean percentage for the non-target PTV V95% was 93.7 ± 9.2% before and 96.6 ± 4.9%after the introduction of guidelines for the 3DCRT, for RA the increase was more relevant, passing from 86.5 ± 13.8% (pre) to 94.5 ± 7.5% (post). The OARs were maximally spared with VMAT technique while the variability between pre and post guidelines was not relevant in both techniques.

Conclusions

The contouring inter-observer variability has dosimetric effects in the PTV coverage. The introduction of guidelines increases the dosimetric consistency for both techniques, with greater improvements for RA technique.

Chronic adverse events and quality of life after radiochemotherapy in anal cancer patients. A single institution experience and review of the literature

PURPOSE

To report on chronic adverse events (CAE) and quality of life (QOL) after radiochemotherapy (RCT) in patients with anal cancer (AC).

PATIENTS AND METHODS

Of 83 patients who had received RCT at our department between 1988 and 2011, 51 accepted the invitation to participate in this QOL study. CAE were evaluated using the Common Terminology Criteria for Adverse Events (CTCAE) v. 4.0 and QOL was assessed with the Functional Assessment of Cancer Therapy-Colorectal (FACT-C) questionnaire.

RESULTS

CAE could be evaluated in 49 patients. There was a tendency toward a higher rate of grade 3 CAE in female patients, i.e. 18 out of 37 (49 %) vs. 2 out of 12 (17 %) male patients (p = 0.089). The most common grade 3 CAE were dyspareunia and vaginal symptoms (itching, burning and dryness) in 35 and 22 % of female patients, respectively, followed by stool incontinence in 13 % of all patients (6 out of 49). Both FACT-C and CAE information were available for 42 patients, allowing evaluation of the impact of CAE on QOL. The median total FACT-C score was 110 (40-132) out of a possible maximum of 136. The absence of grade 3 CAE (115 vs. 94, p = 0.001); an interval of ≥ 67 months after the end of the treatment (111 vs. 107, p = 0.010), no stool incontinence vs. grade 3 stool incontinence (111 vs. 74, p = 0.009), higher education (114 vs. 107, p = 0.013) and no dyspareunia vs. grade 3 dyspareunia (116 vs. 93, p = 0.012) were significantly associated with a higher median FACT-C score.

CONCLUSION

The majority of AC patients treated with RCT have acceptable overall QOL scores, which are comparable to those of the normal population. Patients with grade 3 CAE-particularly dyspareunia and fecal incontinence-have a poorer QOL compared to patients without CAE. In order to improve long-term QOL, future strategies might aim at a reduction in dose to the genitalia and more intensive patient support measures.

Elective inguinal node irradiation in early-stage T2N0 anal cancer: prognostic impact on locoregional control

PURPOSE

To evaluate the influence of elective inguinal node radiation therapy (INRT) on locoregional control (LRC) in patients with early-stage T2N0 anal cancer treated conservatively with primary RT.

METHODS AND MATERIALS

Between 1976 and 2008, 116 patients with T2 node-negative anal cancer were treated curatively with RT alone (n=48) or by combined chemoradiation therapy (CRT) (n=68) incorporating mitomycin C and 5-fluorouracil. Sixty-four percent of the patients (n=74) received elective INRT.

RESULTS

Over a median follow-up of 69 months (range, 4-243 months), 97 (84%) and 95 patients (82%) were locally and locoregionally controlled, respectively. Rates for 5-year actuarial local control, LRC, cancer-specific, and overall survival for the entire population were 81.7% ± 3.8%, 79.2% ± 4.1%, 91.1% ± 3.0%, and 72.1% ± 4.5%, respectively. The overall 5-year inguinal relapse-free survival was 92.3% ± 2.9%. Isolated inguinal recurrence occurred in 2 patients (4.7%) treated without INRT, whereas no groin relapse was observed in those treated with INRT. The 5-year LRC rates for patients treated with and without INRT and with RT alone versus combined CRT were 80.1% ± 5.0% versus 77.8% ± 7.0% (P=.967) and 71.0% ± 7.2% versus 85.4% ± 4.5% (P=.147), respectively. A trend toward a higher rate of grade ≥3 acute toxicity was observed in patients treated with INRT (53% vs 31%, P=.076).

CONCLUSIONS

In cases of node-negative T2 anal cancer, the inguinal relapse rate remains relatively low with or without INRT. The role of INRT in the treatment of early-stage anal carcinoma needs to be investigated in future prospective trials.

Sphincter preservation in anal cancer: a brief review

Management of anal cancer is a challenge. The goal of treatment is to eradicate tumor without sacrificing the anal sphincters. The idea of organ preservation emerged following the discovery of a high complete response rate from preoperative combined chemoradiation (CRT) prior to abdominoperineal resection.CRT is widely accepted as the standard therapy for treating anal squamous cell cancer. The combination of external beam radiotherapy with interstitial brachytherapy increases the dose to the tumor volume and decreases dose to normal tissues. The current goal is to avoid colostomy, and surgery has become a salvage or secondary therapy. In this article, we review the non-surgical management of anal cancer with special emphasis on CRT, role of intensity modulated radiation therapy and brachytherapy.

IMRT for locally advanced anal cancer: clinical experience of the Montpellier Cancer Center

Purpose

To assess outcomes of patients with carcinoma of the anal canal (CAC) treated with intensity-modulated radiation therapy (IMRT).

Method and materials

From August 2007 to January 2011, seventy-two patients suffering from CAC were treated with IMRT. Concurrent chemotherapy was added in case of locally advanced tumors. Radiation course consisted in delivering an initial plan to the PTV1 defined as the primary tumor and the risk area including pelvic and inguinal nodes. Forty-five Gy in daily 1.8 Gy-daily fractions were delivered five days a week. A second plan of 14.4-20 Gy to the primary tumor (PTV2) was administered in 1.8-2 Gy-daily fractions, 5 days a week. We present here the results of dosimetry, toxicities, and clinical outcome of the first 39 patients with a median follow-up of 24 months.

Results

Thirty-one women and eight men were included in the present analysis. Tumors were classified as stages I, II, III and IV in 2, 7, 27 and 2 patients, respectively. Median age was 59 years (range, 38-85). Radiotherapy alone (RT) or combined with chemotherapy (RCT) were delivered in 6 (15%) and 33 (85%) patients, respectively.

Six patients (15%) required a treatment break ≥ 3 days, and median time for treatment break was 8 days (range, 3-14 days). Acute grade 3 gastrointestinal (GI) and genitourinary (GU) toxicities were seen in 10 and 5% of patients, respectively. Grade 4 toxicity was only hematologic and occurred in 12% patients receiving RCT. With a median follow-up of 24 months, no patient experienced any late grade 4 toxicity. The 2-year overall survival rate was 89%, the 2-year local relapse free survival was 77% and the 2-year colostomy-free survival rate was 85%.

Conclusion

IMRT is well tolerated with acceptable treatment interruption allowing dose escalation.

[Intensity-modulated radiation therapy for anal carcinoma]

Anal canal carcinoma are highly curable by irradiation, combined with chemotherapy in locally advanced disease, with preservation of sphincter function. The clinical target volume for the nodes is extended, often including the inguinal nodes, which is not usual for other pelvic tumours. Acute and late effects are correlated with the volume and dose delivered to organs at risk, i. e. small bowel, bladder and increased by concomitant chemotherapy. Intensity modulated irradiation (IMRT) makes it possible to optimize the dose distribution in this "complex U shaped" volume, while maintaining the dose distribution for the target volumes. The conversion from conformal irradiation to IMRT necessitates good knowledge of the definition and skills to delineate target volumes and organs at risk, including new volumes needed to optimize the dose distribution. Dosimetric and clinical benefits of IMRT are described, based on early descriptions and evidence-based publication. The growing development of IMRT in anal canal radiotherapy must be encouraged, and long-term benefits should be soon published. Radiation oncologists should precisely learn IMRT recommendations before starting the technique, and evaluate its early and late results for adverse effects, but also for long-term tumour control.

Update on treatment advances in combined-modality therapy for anal and rectal carcinomas

Concurrent radiation therapy and chemotherapy is the primary treatment for patients with squamous cell tumors of the anal canal, and is also employed in the neoadjuvant setting for patients with stage II and III adenocarcinoma of the rectum. There is constant clinical study involving modifications of chemoradiotherapy regimens in an effort to maximize tumor responses while reducing normal tissue toxicity. This review will discuss established regimens as well as newer and novel treatment approaches to treatment of anal and rectal cancer.

Intensity modulated radiation therapy (IMRT): differences in target volumes and improvement in clinically relevant doses to small bowel in rectal carcinoma

BACKGROUND

A strong dose-volume relationship exists between the amount of small bowel receiving low- to intermediate-doses of radiation and the rates of acute, severe gastrointestinal toxicity, principally diarrhea. There is considerable interest in the application of highly conformal treatment approaches, such as intensity-modulated radiation therapy (IMRT), to reduce dose to adjacent organs-at-risk in the treatment of carcinoma of the rectum. Therefore, we performed a comprehensive dosimetric evaluation of IMRT compared to 3-dimensional conformal radiation therapy (3DCRT) in standard, preoperative treatment for rectal cancer.

METHODS

Using RTOG consensus anorectal contouring guidelines, treatment volumes were generated for ten patients treated preoperatively at our institution for rectal carcinoma, with IMRT plans compared to plans derived from classic anatomic landmarks, as well as 3DCRT plans treating the RTOG consensus volume. The patients were all T3, were node-negative (N = 1) or node-positive (N = 9), and were planned to a total dose of 45-Gy. Pairwise comparisons were made between IMRT and 3DCRT plans with respect to dose-volume histogram parameters.

RESULTS

IMRT plans had superior PTV coverage, dose homogeneity, and conformality in treatment of the gross disease and at-risk nodal volume, in comparison to 3DCRT. Additionally, in comparison to the 3DCRT plans, IMRT achieved a concomitant reduction in doses to the bowel (small bowel mean dose: 18.6-Gy IMRT versus 25.2-Gy 3DCRT; p = 0.005), bladder (V40Gy: 56.8% IMRT versus 75.4% 3DCRT; p = 0.005), pelvic bones (V40Gy: 47.0% IMRT versus 56.9% 3DCRT; p = 0.005), and femoral heads (V40Gy: 3.4% IMRT versus 9.1% 3DCRT; p = 0.005), with an improvement in absolute volumes of small bowel receiving dose levels known to induce clinically-relevant acute toxicity (small bowel V15Gy: 138-cc IMRT versus 157-cc 3DCRT; p = 0.005). We found that the IMRT treatment volumes were typically larger than that covered by classic bony landmark-derived fields, without incurring penalty with respect to adjacent organs-at-risk.

CONCLUSIONS

For rectal carcinoma, IMRT, compared to 3DCRT, yielded plans superior with respect to target coverage, homogeneity, and conformality, while lowering dose to adjacent organs-at-risk. This is achieved despite treating larger volumes, raising the possibility of a clinically-relevant improvement in the therapeutic ratio through the use of IMRT with a belly-board apparatus.

Intensity-modulated radiation therapy versus conventional radiation therapy for squamous cell carcinoma of the anal canal

BACKGROUND

The purpose of this study was to compare outcomes in patients with anal canal squamous cell carcinoma (SCCA) who were treated with definitive chemoradiotherapy by either intensity-modulated radiation therapy (IMRT) or conventional radiotherapy (CRT).

METHODS

Forty-six patients who received definitive chemoradiotherapy from January 1993 to August 2009 were included. Forty-five patients received 5-fluorouracil with mitomycin C (n = 39) or cisplatin (n = 6). Seventeen (37%) were treated with CRT and 29 (63%) with IMRT. The median dose was 54 Gy in both groups. Median follow-up was 26 months (CRT) and 32 months (IMRT). T3-T4 stage (P = .18) and lymph node-positive disease (P = .6) were similar between groups.

RESULTS

The CRT group required longer treatment duration (57 days vs 40 days, P < .0001), more treatment breaks (88% vs 34.5%, P = .001), and longer breaks (12 days vs 1.5 days, P < .0001) than patients treated with IMRT. Eleven (65%) patients in the CRT group experienced grade >2 nonhematologic toxicity compared with 6 (21%) patients in the IMRT group (P = .003). The 3-year overall survival (OS), locoregional control (LRC), and progression-free survival were 87.8%, 91.9%, and 84.2%, respectively, for the IMRT groups and 51.8%, 56.7%, and 56.7%, respectively, for the CRT group (all P < .01). On multivariate analysis, T stage, use of IMRT, and treatment duration were associated with OS, and T stage and use of IMRT were associated with LRC.

CONCLUSIONS

The use of IMRT was associated with less toxicity, reduced need for treatment breaks, and excellent LRC and OS compared with CRT in patients with SCCA of the anal canal.