NRG Oncology Radiation Therapy Oncology Group 0822: A Phase 2 Study of Preoperative Chemoradiation Therapy Using Intensity Modulated Radiation Therapy in Combination With Capecitabine and Oxaliplatin for Patients With Locally Advanced Rectal Cancer

Significance of MRI-based radiomics in predicting pathological complete response to neoadjuvant chemoradiotherapy of locally advanced rectal cancer: A narrative review

Neoadjuvant chemoradiotherapy is the standard treatment for patients with locally advanced rectal cancers owing to its ability to downstage primary tumours. Some patients can achieve pathological complete response after neoadjuvant therapy, and can adopt a "watch and wait" treatment strategy to avoid overtreatment. Therefore, it is essential to develop strategies for predicting responses to neoadjuvant therapy. Radiomics has shown great potential in extracting tumour features from high-throughput medical images for the construction of mathematics models for predicting the effects of anticancerous therapies. Herein, we explored MRI-based radiomics and found that it can predict responses of locally advanced rectal cancers to chemoradiation. Efficient radiomics model allow early-stage prediction of the effect of neoadjuvant chemoradiotherapy on locally advanced rectal cancers. It helps clinicians to make informed therapeutic decisions. In this review, we discuss the workflow of radiomics, and summarize the clinical application of MRI-based radiomics in predicting pathological complete response to neoadjuvant chemoradiotherapy of locally advanced rectal cancer.

Executive Summary of the American Radium Society on Appropriate Use Criteria for Nonoperative Management of Rectal Adenocarcinoma: Systematic Review and Guidelines

For patients with rectal cancer, the standard approach of chemotherapy, radiation therapy, and surgery (trimodality therapy) is associated with significant long-term toxicity and/or colostomy for most patients. Patient options focused on quality of life (QOL) have dramatically improved, but there remains limited guidance regarding comparative effectiveness. This systematic review and associated guidelines evaluate how various treatment strategies compare to each other in terms of oncologic outcomes and QOL. Cochrane and Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) methodology were used to search for prospective and retrospective trials and meta-analyses of adequate quality within the Ovid Medline database between January 1, 2012, and June 15, 2023. These studies informed the expert panel, which rated the appropriateness of various treatments in 6 clinical scenarios through a well-established consensus methodology (modified Delphi). The search process yielded 197 articles that advised voting. Increasing data have shown that nonoperative management (NOM) and primary surgery result in QOL benefits noted over trimodality therapy without detriment to oncologic outcomes. For patients with rectal cancer for whom total mesorectal excision would result in permanent colostomy or inadequate bowel continence, NOM was strongly recommended as usually appropriate. Restaging with tumor response assessment approximately 8 to 12 weeks after completion of radiation therapy/chemoradiation therapy was deemed a necessary component of NOM. The panel recommended active surveillance in the setting of a near-complete or complete response. In the setting of NOM, 54 to 56 Gy in 27 to 31 fractions concurrent with chemotherapy and followed by consolidation chemotherapy was recommended. The panel strongly recommends primary surgery as usually appropriate for a T3N0 high rectal tumor for which low anterior resection and adequate bowel function is possible, with adjuvant chemotherapy considered if N+. Recent data support NOM and primary surgery as important options that should be offered to eligible patients. Considering the complexity of multidisciplinary management, patients should be discussed in a multidisciplinary setting, and therapy should be tailored to individual patient goals/values.

Role of Oxaliplatin in the Neoadjuvant Concurrent Chemoradiotherapy in Locally Advanced Rectal Cancer: a Review of Evidence

The treatment of locally advanced rectal cancer (LARC) is a challenging situation for radiation oncologists and colorectal surgeons. Most current approaches recommend neoadjuvant fluorouracil or capecitabine-based chemoradiotherapy followed by surgery as a standard of care. Intensification of concurrent chemotherapy by adding oxaliplatin to fluorouracil or capecitabine backbone to get better outcomes is the matter that has remained unresolved. In this review, we searched Medline and Google Scholar databases and selected 28 prospective phase II and III clinical trials that addressed this question. We discussed the potential advantages and drawbacks of incorporating oxaliplatin into concurrent chemoradiation therapy. We tried to define whether adding oxaliplatin to concurrent chemoradiation with excellent performance and high-risk features benefits some subpopulations. The available literature suggests that by adding oxaliplatin there are some benefits in enhancing response to neoadjuvant chemoradiotherapy, however, without any translated improvements in long-term outcomes including overall and disease-free survival.

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.

Disparities in Clinical Trial Enrollment and Reporting in Rectal Cancer: A Systematic Review and Demographic Comparison to the National Cancer Database

BACKGROUND

Cancer care guidelines based on clinical trial data in homogenous populations may not be applicable to all rectal cancer patients. The aim of this study was to evaluate whether patients enrolled in rectal cancer clinical trials (CTs) are representative of United States (U.S.) rectal cancer patients.

METHODS

Prospective rectal cancer CTs from 2010 to 2019 in the United States were systematically reviewed. In trials with multiple arms reporting separate demographic variables, each arm was considered a separate CT group in the analysis. Demographic variables considered in the analysis were age, sex, race/ethnicity, facility location throughout the United States, rural vs urban geography, and facility type. Participant demographics from trial and the National Cancer Database (NCDB) participants were compared using chi-squared goodness of fit and one-sample t-test where applicable.

RESULTS

Of 50 CT groups identified, 42 (82%) studies reported mean or median age. Trial participants were younger compared to NCDB patients (P < .001 all studies). All but three trials had fewer female patients than NCDB (48.2% female, P < .001). Less than half the CT groups reported on race or ethnicity. Eighteen out of 22 trials (82%) had a smaller percentage of Black patients and 4 out of 8 (50%) trials had fewer Hispanic or Spanish origin patients than the NCDB. No CTs reported comorbidities, socioeconomic factors, or education. CT primary sites were largely at academic centers and in urban areas.

CONCLUSION

The present study supports the need for improved demographic representation and transparency in rectal cancer clinical trials.

Dosimetric effect of collimator rotation on intensity modulated radiotherapy and volumetric modulated arc therapy for rectal cancer radiotherapy

INTRODUCTION

Intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) are the main radiotherapy techniques for treating and managing rectal cancer. Collimator rotation is one of the crucial parameters in radiotherapy planning, and its alteration can cause dosimetric variations. This study assessed the effect of collimator rotation on the dosimetric results of various IMRT and VMAT plans for rectal cancer.

MATERIALS AND METHODS

Computed tomography (CT) images of 20 male patients with rectal cancer were utilized for IMRT and VMAT treatment planning with various collimator angles. Nine different IMRT techniques (5, 7, and 9 coplanar fields with collimator angles of 0°, 45°, and 90°) and six different VMAT techniques (1 and 2 full coplanar arcs with collimator angles of 0°, 45°, and 90°) were planned for each patient. The dosimetric results of various treatment techniques for target tissue (conformity index [CI] and homogeneity index [HI]) and organs at risk (OARs) sparing (parameters obtained from OARs dose-volume histograms [DVH]) as well as radiobiological findings were analyzed and compared.

RESULTS

The 7-fields IMRT technique demonstrated lower bladder doses (V40Gy, V45Gy), unaffected by collimator rotation. The 9-fields IMRT and 2-arcs VMAT (excluding the 90-degree collimator) had the lowest V35Gy and V45Gy. A 90-degree collimator rotation in 2-arcs VMAT significantly increased small bowel and bladder V45Gy, femoral head doses, and HI values. Radiobiologically, the 90-degree rotation had adverse effects on small bowel NTCP (normal tissue complication probability). No superiority was found for a 45-degree collimator rotation over 0 or 30 degrees in VMAT techniques.

CONCLUSION

Collimator rotation had minimal impact on dosimetric parameters in IMRT planning but is significant in VMAT techniques. A 90-degree rotation in VMAT, particularly in a 2-full arc technique, adversely affects PTV homogeneity index, bladder dose, and small bowel NTCP. Other evaluated collimator angles did not significantly affect VMAT dosimetrical or radiobiological outcomes.

Gender-Affirming Surgery and Cancer: Considerations for Radiation Oncologists for Pelvic Radiation in Transfeminine Patients

Access to gender-affirming surgery is increasing for many transgender and nonbinary people in the United States, and radiation oncologists must be equipped to care for patients who have undergone such surgery in the region of their planned radiation treatment field. There are no guidelines for radiation treatment planning after gender-affirming surgery, and most oncologists do not receive training in the unique needs of transgender people with cancer. We review common gender-affirming genitopelvic surgeries for transfeminine people, including vaginoplasty, labiaplasty, and orchiectomy, and summarize the existing literature on the treatment of cancers of the neovagina, anus, rectum, prostate, and bladder in these patients. We also describe our systematic treatment approach and rationale for pelvic radiation treatment planning.

Preoperative Radiotherapy with a Simultaneous Integrated Boost Compared to Chemoradiotherapy for cT3-4 Rectal Cancer: Long-Term Results of a Multicenter Randomized Study

BACKGROUND

Preoperative chemoradiotherapy (CRT) is the standard treatment for T3-4 rectal cancer. Here, we compared image-guided and intensity-modulated RT (IG-IMRT) with a simultaneous integrated boost (SIB) (instead of concomitant chemotherapy) versus CRT in a multi-centric randomized trial.

METHODS

cT3-4 rectal cancer patients were randomly assigned to receive preoperative IG-IMRT 46 Gy/23 fractions plus capecitabine 825 mg/m² twice daily (CRT arm) or IG-IMRT 46 Gy/23 fractions with an SIB to the rectal tumor up to a total dose of 55.2 Gy (RTSIB arm).

RESULTS

A total of 174 patients were randomly assigned between April 2010 and May 2014. Grade 3 acute toxicities were 6% and 4% in the CRT and RTSIB arms, respectively. The mean fractional change in SUVmax at 5 weeks after completion of preoperative RT were -55.8% (±24.0%) and -52.9% (±21.6%) for patients in the CRT arm and RTSIB arm, respectively (p = 0.43). The pathologic complete response rate was 24% with CRT compared to 14% with RTSIB. There were no differences in 5-year overall survival (OS), progression-free survival (PFS) or local control (LC).

CONCLUSIONS

The preoperative RTSIB approach was not inferior to CRT in terms of metabolic response, toxicity, OS, PFS and LC, and could be considered an available option for patients unfit for fluorouracil-based CRT.

Patient-reported Bowel Function and Bowel-related Quality of Life After Pelvic Radiation for Rectal Adenocarcinoma: The Impact of Radiation Fractionation and Surgical Resection

INTRODUCTION

Multimodality treatment for locally advanced rectal cancer (LARC) can include long-course radiotherapy (LCRT) or short course radiotherapy (SCRT). Nonoperative management is increasingly pursued for those achieving a complete clinical response. Data regarding long-term function and quality-of-life (QOL) are limited.

METHODS

Patients with LARC treated with radiotherapy from 2016 to 2020 completed the Functional Assessment of Cancer Therapy- General (FACT-G7), the Low Anterior Resection Syndrome Score (LARS) and the Fecal Incontinence QOL Scale (FIQOL). Univariate and multivariable linear regression analyses identified associations between clinical variables including radiation fractionation and the use of surgery versus non-operative management.

RESULTS

Of 204 patients surveyed, 124 (60.8%) responded. Median (interquartile range) time from radiation to survey completion was 30.1 (18.3-43) months. Seventy-nine (63.7%) respondents received LCRT, and 45 (36.3%) received SCRT; 101 (81.5%) respondents underwent surgery, and 23 (18.5%) pursued nonoperative management. There were no differences in LARS, FIQoL or FACT-G7 between patients receiving LCRT versus SCRT. On multivariable analysis, only nonoperative management was associated with lower LARS score signifying less bowel dysfunction. Nonoperative management and female sex were associated with a higher FIQoL score signifying less disruption and distress from fecal incontinence issues. Finally, lower BMI at the time of radiation, female sex, and higher FIQoL score were associated with higher FACT-G7 scores signifying better overall QOL.

CONCLUSIONS

These results suggest long-term patient-reported bowel function and QOL may be similar for individuals receiving SCRT and LCRT for the treatment of LARC, but nonoperative management may lead to improved bowel function and QOL.

A clinically relevant online patient QA solution with daily CT scans and EPID-based in vivo dosimetry: a feasibility study on rectal cancer

Objective. Adaptive radiation therapy (ART) could protect organs at risk (OARs) while maintain high dose coverage to targets. However, there is still a lack of efficient online patient quality assurance (QA) methods, which is an obstacle to large-scale adoption of ART. We aim to develop a clinically relevant online patient QA solution for ART using daily CT scans and EPID-based in vivo dosimetry. Approach. Ten patients with rectal cancer at our center were included. Patients’ daily CT scans and portal images were collected to generate reconstructed 3D dose distributions. Contours of targets and OARs were recontoured on these daily CT scans by a clinician or an auto-segmentation algorithm, then dose-volume indices were calculated, and the percent deviation of these indices to their original plans were determined. This deviation was regarded as the metric for clinically relevant patient QA. The tolerance level was obtained using a 95% confidence interval of the QA metric distribution. These deviations could be further divided into anatomically relevant or delivery relevant indicators for error source analysis. Finally, our QA solution was validated on an additional six clinical patients. Main results. In rectal cancer, the 95% confidence intervals of the QA metric for PTV ΔD 95 (%) were [−3.11%, 2.35%], and for PTV ΔD 2 (%) were [−0.78%, 3.23%]. In validation, 68% for PTV ΔD 95 (%), and 79% for PTV ΔD 2 (%) of the 28 fractions are within tolerances of the QA metrics. one patient’s dosimetric impact of anatomical variations during treatment were observed through the source of error analysis. Significance. The online patient QA solution using daily CT scans and EPID-based in vivo dosimetry is clinically feasible. Source of error analysis has the potential for distinguishing sources of error and guiding ART for future treatments.

[Impact of IMRT for neoadjuvant rectal cancer?]

The standard management of locally advanced rectal tumors as cT3-T4 and/or N0/N1 is based on preoperative treatment combining radiotherapy of 45 to 50Gy and chemotherapy based on 5-fluorouracil. Intensity-modulated radiotherapy has already shown its interest compared to conformal radiotherapy in other locations, like in pelvic cancer. The role of intensity-modulated radiotherapy in the pre/postoperative treatment of rectal cancers is not a standard of care. Published studies showed its feasibility with the objective of less toxicity with equivalent efficacy.

Assessment of Radiation-Induced Bladder and Bowel Cancer Risks after Conventionally and Hypo-Fractionated Radiotherapy for the Preoperative Management of Rectal Carcinoma

Preoperative management of rectal carcinoma can be performed by employing either conventionally or hypo-fractionated Radiotherapy (CFRT or HFRT, respectively), delivered by Intensity Modulated Radiotherapy (IMRT) or Volumetric Modulated Arc Therapy (VMAT) plans, employing 6 MV or 10 MV photon beams. This study aims to dosimetrically and radiobiologically compare all available approaches, with emphasis on the risk of radiation-induced second cancer to the bladder and bowel. Computed Tomography (CT) scans and relevant radiotherapy contours from 16 patients were anonymized and analyzed retrospectively. For each case, CFRT of 25 × 2 Gy and HFRT of 5 × 5 Gy were both considered. IMRT and VMAT plans using 6 MV and 10 MV photons were prepared. Plan optimization was performed, considering all clinically used plan quality indices and dose–volume constraints for the critical organs. Resulting dose distributions were analyzed and compared. Moreover, the Lifetime Attributable Risk (LAR) for developing radiation-induced bladder and bowel malignancies were assessed using a non-linear mechanistic model, assuming patient ages at treatment of 45, 50, 55 and 60 years. All 128 plans created were clinically acceptable. Risk of second bladder cancer reached 0.26% for HFRT (5 × 5 Gy) and 0.19% for CFRT (25 × 2 Gy) at the age of 45. Systematically higher risks were calculated for HFRT (5 × 5 Gy) as compared to CFRT (25 × 2 Gy), with 6 MV photons resulting in slightly increased LAR, as well. Similar or equal bowel cancer risks were calculated for all techniques and patient ages investigated (range 0.05–0.14%). This work contributes towards radiotherapy treatment protocol selection criteria for the preoperative irradiation of rectal carcinoma. However, more studies are needed to establish the associated radiation-induced risk of each RT protocol.

CT-Only Radiotherapy: An Exploratory Study for Automatic Dose Prediction on Rectal Cancer Patients Via Deep Adversarial Network

Purpose

Current deep learning methods for dose prediction require manual delineations of planning target volume (PTV) and organs at risk (OARs) besides the original CT images. Perceiving the time cost of manual contour delineation, we expect to explore the feasibility of accelerating the radiotherapy planning by leveraging only the CT images to produce high-quality dose distribution maps while generating the contour information automatically.

Materials and Methods

We developed a generative adversarial network (GAN) with multi-task learning (MTL) strategy to produce accurate dose distribution maps without manually delineated contours. To balance the relative importance of each task (i.e., the primary dose prediction task and the auxiliary tumor segmentation task), a multi-task loss function was employed. Our model was trained, validated and evaluated on a cohort of 130 rectal cancer patients.

Results

Experimental results manifest the feasibility and improvements of our contour-free method. Compared to other mainstream methods (i.e., U-net, DeepLabV3+, DoseNet, and GAN), the proposed method produces the leading performance with statistically significant improvements by achieving the highest HI of 1.023 (3.27E-5) and the lowest prediction error with ΔD95 of 0.125 (0.035) and ΔDmean of 0.023 (4.19E-4), respectively. The DVH differences between the predicted dose and the ideal dose are subtle and the errors in the difference maps are minimal. In addition, we conducted the ablation study to validate the effectiveness of each module. Furthermore, the results of attention maps also prove that our CT-only prediction model is capable of paying attention to both the target tumor (i.e., high dose distribution area) and the surrounding healthy tissues (i.e., low dose distribution areas).

Conclusion

The proposed CT-only dose prediction framework is capable of producing acceptable dose maps and reducing the time and labor for manual delineation, thus having great clinical potential in providing accurate and accelerated radiotherapy. Code is available at https://github.com/joegit-code/DoseWithCT

Consensus Quality Measures and Dose Constraints for Rectal Cancer From the Veterans Affairs Radiation Oncology Quality Surveillance Program and American Society for Radiation Oncology (ASTRO) Expert Panel

PURPOSE

Ensuring high quality, evidence-based radiation therapy for patients with cancer is of the upmost importance. To address this need, the Veterans Affairs (VA) Radiation Oncology Program partnered with the American Society for Radiation Oncology and established the VA Radiation Oncology Quality Surveillance program. As part of this ongoing effort to provide the highest quality of care for patients with rectal cancer, a blue-ribbon panel comprised of rectal cancer experts was formed to develop clinical quality measures.

METHODS AND MATERIALS

The Rectal Cancer Blue Ribbon panel developed quality, surveillance, and aspirational measures for (a) initial consultation and workup, (b) simulation, treatment planning, and treatment, and (c) follow-up. Twenty-two rectal cancer specific measures were developed (19 quality, 1 aspirational, and 2 surveillance). In addition, dose-volume histogram constraints for conventional and hypofractionated radiation therapy were created.

CONCLUSIONS

The quality measures and dose-volume histogram for rectal cancer serves as a guideline to assess the quality of care for patients with rectal cancer receiving radiation therapy. These quality measures will be used for quality surveillance for veterans receiving care both inside and outside the VA system to improve the quality of care for these patients.

Simultaneous Integrated Boost Volumetric Modulated Arc Therapy for Rectal Cancer: Long-Term Results after Protocol-Based Treatment

Background

Volumetric modulated arc therapy (VMAT) with simultaneous integrated boost (SIB) is an advanced form of radiotherapy (RT) technology. The purpose of this study was to report long-term treatment outcomes in patients with locally advanced rectal cancer undergoing VMAT-SIB based concurrent chemoradiotherapy (CRT).

Methods

Between January 2016 and January 2018, a total of 22 patients with operable stage II-III rectal adenocarcinoma were recruited for the pre-designed VMAT-SIB RT protocol. All patients underwent standard diagnostic and staging work-up. The RT target volumes included the following areas: PTV1 = mesorectum that contained gross tumors and enlarged lymph node regions and PTV2 = mesorectum and regional lymphatics from L4-5/S1 to 3-4 cm below the tumor or levator ani muscle, excluding PTV1. The VMAT-SIB dose prescription was as follows: PTV1 = 52.5 Gy/daily 2.1 Gy/25 fractions, PTV2 = 45 Gy/daily 1.8 Gy/25 fractions.

Results

The mean age of the study population was 64 (range, 18-84) years, and 15 (68.2%) patients were male. Radical operation (total mesorectal excision) was performed by either low anterior resection, ultralow anterior resection, or abdominal perineal resection. All five (22.7%) of the patients with confirmed increasing serum carcinoembryonic antigen (CEA) level at diagnosis showed normalization of serum CEA level after the planned treatment. Among 20 patients who underwent preoperative CRT and surgery, tumor down staging in T- and N-stages was achieved in 10 patients (50%) and 13 patients (65%), respectively, with 20% of ypT0/Tis. With a median follow-up of 54.2 (range, 22.6-61.1) months, the 5-year disease-free survival, overall survival, and local control rates were 64.6%, 81.8%, and 84.4%, respectively. Five patients developed distant metastasis and one developed local recurrence as a first event. Two cases with anastomosis site leakage, three with adhesive ileus, and two with abscess formation were observed during postoperative periods.

Conclusions

The current VMAT-SIB-based CRT protocol provided acceptable treatment and toxicity outcomes.

Preoperative chemoradiotherapy for locally advanced low rectal cancer using intensity-modulated radiotherapy to spare the intestines: a single-institutional pilot trial

The irradiated volume of intestines is associated with gastrointestinal toxicity in preoperative chemoradiotherapy for rectal cancer. The current trial prospectively explored how much of the irradiated volume of intestines was reduced by intensity-modulated radiotherapy (IMRT) compared with 3-dimensional conformal radiotherapy (3DCRT) and whether IMRT might alleviate the acute gastrointestinal toxicity in this population. The treatment protocol encompassed preoperative chemoradiotherapy using IMRT plus surgery for patients with clinical T3-4, N0-2 low rectal cancer. IMRT delivered 45 Gy per 25 fractions for gross tumors, mesorectal and lateral lymph nodal regions, and tried to reduce the volume of intestines receiving 15 Gy (V15 Gy) < 120 cc and V45 Gy ≤ 0 cc, respectively, while keeping target coverage. S-1 and irinotecan were concurrently administered. Acute gastrointestinal toxicity, rates of clinical downstaging, sphincter preservation, local regional control (LRC) and overall survival (OS) were evaluated. Twelve enrolled patients completed the chemoradiotherapy protocol. The volumes of intestines receiving medium to high doses were reduced by the current IMRT protocol compared to 3DCRT; however, the predefined constraint of V15 Gy was met only in three patients. The rate of ≥ grade 2 gastrointestinal toxicity excluding anorectal symptoms was 17%. The rates of clinical downstaging, sphincter preservation, three-year LRC and OS were 75%, 92%, 92% and 92%, respectively. In conclusion, preoperative chemoradiotherapy using IMRT for this population might alleviate acute gastrointestinal toxicity, achieving high LRC and sphincter preservation; although further advancement is required to reduce the irradiated volume of intestines, especially those receiving low doses.

Locally Advanced Rectal Cancer: What We Learned in the Last Two Decades and the Future Perspectives

The advancement in surgical techniques, optimization of systemic chemoradiotherapy, and development of refined diagnostic and imaging modalities have brought a phenomenal shift in the treatment of the locally advanced rectal cancer. Although each therapeutic option has shown substantial progress in their field, it is finding their ideal amalgamation which has baffled the clinician and researchers alike. In the effort to identifying the perfect salutary treatment plan, we have even shifted our attention from the trimodal approach to non-operative "watchful waiting" to more recent individualized care. In this article, we acknowledge the scientific progress in the management of locally advanced rectal cancer and compare the opportunities as well as the obstacles while implementing them clinically. We also explore the current challenges and controversies surrounding the multidisciplinary approach and highlight the new trends and recent advances with an ultimate goal to improve the patients' quality of life.

Preoperative intensity-modulated chemoradiotherapy with simultaneous integrated boost in rectal cancer: five-year follow-up results of a phase II study

Background

We conducted a phase II study to investigate the feasibility and safety of preoperative radiochemo-therapy experimental fractionation, using intensity-modulated radiation therapy with simultaneous integrated boost (IMRT SIB) to shorten the overall treatment time without dose escalation in intermediate/locally advanced rectal cancer with the aim to improving treatment outcome.

Patients and methods

A total of 51 patients with operable stage II–III rectal carcinoma were included between January 2014 and January 2015. Fifty patients completed preoperative IMRT treatment with an elective dose of 41.8 Gy and simultaneously delivered 46.2 Gy to T2/T3 and 48.4 Gy to T4 tumour in 22 fractions, with concomitant capecitabine (825 mg/m2/12 h, including at weekends). Median follow-up was 70 months (range 11–80 m).

Results

Forty-seven patients completed treatment per protocol. Acute toxicity occurred in 2 (4%) patients. R0 resection was achieved in all but 1 and pathologic complete response (pCR) in 12 (25.5%) patients who had 5-year overall survival (OS), disease-free survival (DFS) and local control (LC) of 91.7%, 100% and 100%, respectively. The intention-to-treat analysis showed that the type of surgery significantly moderated OS and DFS, while total downstaging and pN were predictive for DFS only. For treatment per protocol 5-year OS, DFS and LC were 80.9% (95% confidence interval [CI] 69.7–92.1), 77.1% (95% CI 65.1–89.1) and 95.2% (95% CI 88.7–100), respectively. The proportion of patients with severe late (CTCAE G ≥ 3) gastrointestinal, urinary and sexual toxicity was 15%, 2% and 8% respectively, with one reported secondary carcinoma.

Conclusions

Preoperative IMRT-SIB without dose escalation was well tolerated, with a low acute toxicity profile, we achieved a high rate of pCR and showed encouraging 5-year OS, DFS and LC.

The association of age with acute toxicities in NRG oncology combined modality lower GI cancer trials

PURPOSE

Expected toxicity from chemoradiation (CRT) is an important factor in treatment decisions but is poorly understood in older adults with lower gastrointestinal (GI) malignancies. Our objective was to compare acute adverse events (AAEs) of older and younger adults with lower GI malignancies treated on NRG studies.

METHODS

Data from 6 NRG trials, testing combined modality therapy in patients with anal or rectal cancer, were used to test the hypothesis that older age was associated with increased AAEs. AAEs and compliance with protocol-directed therapy were compared between patients aged ≥70 and < 70. Categorical variables were compared across age groups using the chi-square test. The association of age on AAEs was evaluated using a covariate-adjusted logistic regression model, with odds ratio (OR) reported. To adjust for multiple comparisons, a p-value <0.01 was considered statistically significant.

RESULTS

There were 2525 patients, including 380 patients ≥70 years old (15%) evaluable. Older patients were more likely to have worse baseline performance status (PS 1 or 2) (23% vs. 16%, p = 0.001), but otherwise baseline characteristics were similar. Older patients were less likely to complete their chemotherapy (78% vs. 87%, p < 0.001), but had similar RT duration. On univariate analysis, older patients were more likely to experience grade ≥ 3 GI AAEs (36% vs. 23%, p < 0.001), and less likely to experience grade ≥ 3 skin AAEs (8% vs. 14%, p = 0.002). On multivariable analysis, older age was associated with grade ≥ 3 GI AAE (OR 1.93, 95% CI: 1.52, 2.47, p < 0.001) after adjusting for sex, race, PS, and disease site.

CONCLUSIONS

Older patients with lower GI cancers who underwent CRT were less likely to complete chemotherapy and had higher rates of grade 3+ GI AAEs. These results can be used to counsel older adults prior to treatment and manage expected toxicities throughout pelvic CRT.

Optimization of Field Design in the Treatment of Rectal Cancer with Intensity Modulated Proton Beam Radiation Therapy: How Many Fields Are Needed to Account for Rectal Distension Uncertainty?

Purpose

Preoperative chemoradiation represents the standard of care in patients with locally advanced rectal cancer. Robustness is often compromised in the setting of proton beam therapy owing to the sensitivity of proton particles to tissue heterogeneity, such as with intestinal gas. The ideal beam arrangement to mitigate the anatomic uncertainty caused by intestinal gas is not well defined.

Methods and Materials

We developed pencil beam scanning plans using (1) 1-beam posteroanterior (PA) plans, (2) 2-beam with right and left posterior oblique (RPO and LPO) plans, (3) 3-beam with PA and opposed lateral plans, and (4) 5-beam with PA, RPO, LPO, and opposed lateral plans. We created 12 plans with robustness optimization and ran a total of 60 plan evaluations for varying degrees of intestinal gas distension to evaluate which plans would maintain clinical goals to the greatest degree.

Results

A single PA beam resulted in considerable loss of target coverage to the clinical target volume prescribed 50 Gy (volume receiving 100% of the prescribed dose [V_100%] < 90%) with rectal distension ≥3 cm in diameter in the short axis. In contrast, the other field designs maintained coverage with up to 5 cm of distension. On plans generated based on a 5-cm distended rectum with air medium, the 1-beam, 3-beam, and 5-beam arrangements resulted in loss of target coverage (V_100% < 90%) with rectal contraction ≤3 cm, whereas the 2-beam arrangement maintained coverage to as low as 2 cm. On plans generated based on a 3-cm distension of the rectum, both the 2-beam and 3-beam arrangements maintained V_100% > 90% even with collapsed rectum to as low as 1 cm, simulating a patient treatment scenario without any rectal gas.

Conclusions

A single PA beam should be avoided when using proton beam therapy for rectal cancer. RPO/LPO and PA/opposed lateral arrangements may both be considered; RPO/LPO is favored to reduce integral dose and avoid beams traversing the hips. In patients for whom the plan CT has rectal distension of ≥3 cm, resimulation or strategies to reduce intestinal gas should be strongly considered.

Effective Organs-at-Risk Dose Sparing in Volumetric Modulated Arc Therapy Using a Half-Beam Technique in Whole Pelvic Irradiation

BACKGROUND

Although there are some controversies regarding whole pelvic radiation therapy (WPRT) due to its gastrointestinal and hematologic toxicities, it is considered for patients with gynecological, rectal, and prostate cancer. To effectively spare organs-at-risk (OAR) doses using multi-leaf collimator (MLC)'s optimal segments, potential dosimetric benefits in volumetric modulated arc therapy (VMAT) using a half-beam technique (HF) were investigated for WPRT.

METHODS

While the size of a fully opened field (FF) was decided to entirely include a planning target volume in all beam's eye view across arc angles, the HF was designed to use half the FF from the isocenter for dose optimization. The left or the right half of the FF was alternatively opened in VMAT-HF using a pair of arcs rotating clockwise and counterclockwise. Dosimetric benefits of VMAT-HF, presented with dose conformity, homogeneity, and dose-volume parameters in terms of modulation complex score, were compared to VMAT optimized using the FF (VMAT-FF). Consequent normal tissue complication probability (NTCP) by reducing the irradiated volumes was evaluated as well as dose-volume parameters with statistical analysis for OAR. Moreover, beam-on time and MLC position precision were analyzed with log files to assess plan deliverability and clinical applicability of VMAT-HF as compared to VMAT-FF.

RESULTS

While VMAT-HF used 60%-70% less intensity modulation complexity than VMAT-FF, it showed superior dose conformity. The small intestine and colon in VMAT-HF showed a noticeable reduction in the irradiated volumes of up to 35% and 15%, respectively, at an intermediate dose of 20-45 Gy. The small intestine showed statistically significant dose sparing at the volumes that received a dose from 15 to 45 Gy. Such a dose reduction for the small intestine and colon in VMAT-HF presented a significant NTCP reduction from that in VMAT-FF. Without sacrificing the beam delivery efficiency, VMAT-HF achieved effective OAR dose reduction in dose-volume histograms.

CONCLUSIONS

VMAT-HF led to deliver conformal doses with effective gastrointestinal-OAR dose sparing despite using less modulation complexity. The dose of VMAT-HF was delivered with the same beam-on time with VMAT-FF but precise MLC leaf motions. The VMAT-HF potentially can play a valuable role in reducing OAR toxicities associated with WPRT.

Intensity-modulated Radiotherapy for Rectal Cancer in the UK in 2020

AIMS

Preoperative (chemo)radiotherapy followed by total mesorectal excision is the current standard of care for patients with locally advanced rectal cancer. The use of intensity-modulated radiotherapy (IMRT) for rectal cancer is increasing in the UK. However, the extent of IMRT implementation and current practice was not previously known. A national survey was commissioned to investigate the landscape of IMRT use for rectal cancer and to inform the development of national rectal cancer IMRT guidance.

MATERIALS AND METHODS

A web-based survey was developed by the National Rectal Cancer IMRT Guidance working group in collaboration with the Royal College of Radiologists and disseminated to all UK radiotherapy centres. The survey enquired about the implementation of IMRT with a focus on the following aspects of the workflow: dose fractionation schedules and use of a boost; pre-treatment preparation and simulation; target volume/organ at risk definition; treatment planning and treatment verification. A descriptive statistical analysis was carried out.

RESULTS

In total, 44 of 63 centres (70%) responded to the survey; 30/44 (68%) and 36/44 (82%) centres currently use IMRT to treat all patients and selected patients with rectal cancer, respectively. There was general agreement concerning several aspects of the IMRT workflow, including patient positioning, use of intravenous contrast and bladder protocols. Greater variation in practice was identified regarding rectal protocols; use of a boost to primary/nodal disease; target volume delineation; organ at risk delineation and dose constraints and treatment verification. Delineation of individual small bowel loops and daily volumetric treatment verification were considered potentially feasible by most centres.

CONCLUSION

This survey identified that IMRT is already used to treat rectal cancer in many UK radiotherapy centres, but there is heterogeneity between centres in its implementation and practice. These results have been a valuable aid in framing the recommendations within the new National Rectal Cancer IMRT Guidance.

Efficacy and tolerability of preoperative chemoradiotherapy with S-1 alone for locally advanced rectal cancer

Preoperative chemoradiotherapy with capecitabine or 5-fluorouracil is a standard treatment for locally advanced rectal cancer (LARC). S-1, a prodrug of 5-fluorouracil, is a candidate for this chemoradiotherapy regimen in Japan; however, treatment outcomes after S-1 treatment alone are not clear. This study aimed to assess the efficacy and tolerability of preoperative chemoradiotherapy with S-1 alone for LARC. We retrospectively evaluated 54 LARC patients who underwent preoperative chemoradiotherapy with S-1 alone in our institution between 2005 and 2017. The clinical tumor stage was cT2-3 in 31 patients and cT4 in 23 patients, and lymph node metastases were clinically evident in 31 patients. S-1, at a dose of 80 mg/m2/day, was orally administered during radiotherapy. A total dose of 45-50.4 Gy was delivered in 25-28 fractions (median: 50.4 Gy). Surgical resections were scheduled 6-10 weeks after chemoradiotherapy completion. The 3- and 5-year overall survival rates were 92.4 and 72.8%, respectively, with a median follow-up time of 51 months. The 3- and 5-year local control rates were 96.2 and 85.9%, respectively. A pathological complete response was observed in 7 patients (13.0%) at the time of surgery. Ten patients (18.5%) had grade 3 acute toxicities and 5 patients (9.3%) had grade 3 late toxicities. No grade 4 or 5 toxicities were observed. Preoperative chemoradiotherapy with S-1 alone followed by total mesorectal excision resulted in a low incidence of toxicities and comparable clinical results. Therefore, S-1 alone can be a treatment option for preoperative chemoradiotherapy in LARC patients.

Impact of Treatment Sequencing on Survival for Patients with Locally Advanced Gastric Cancer

BACKGROUND

Data are limited concerning the survival outcomes of locally advanced gastric cancer patients according to the multimodality therapy (MMT) administered.

METHODS

Single institution, retrospective analysis of 235 patients with locally advanced gastric cancer from 2001 to 2015. All patients met criteria for curative-intent surgery and chemotherapy ± radiation therapy. Treatment regimens were: (1) surgery first with adjuvant chemoradiation therapy (S + Adj); (2) perioperative chemotherapy + surgery (Periop); and (3) total neoadjuvant therapy followed by surgery (TNT + S).

RESULTS

One hundred twenty-eight (60.0%) patients received S + Adj, 69 (26.8%) Periop, and 38 (13.2%) TNT + S. Of the 235 patients, 222 (94.5%) received surgery. All intended therapy was received by 81.6% of TNT + S, 44.5% of S + Adj, and 42.0% of Periop patients. MMT was significantly more likely to be completed by TNT + S patients (HR 6.67, p < 0.001). At a median follow-up of 37 months, survival rates on an intention-to-treat basis with TNT + S, Periop, and S + Adj were 52.6%, 59.4%, and 45.3%, respectively. Regimen and completion of MMT significantly affected overall mortality risk. Compared with Periop, TNT + S had similar mortality risk (hazard ratio [HR] 1.28, p = 0.421), whereas S + Adj had increased mortality risk (HR 1.64, p = 0.027).

CONCLUSIONS

The choice of treatment sequencing has a major impact on completion rates of multimodal therapy in patients with locally advanced gastric cancer. Less than 50% of patients treated with upfront surgery or perioperative chemotherapy receive all intended therapies. TNT has higher intended therapy completion rates and comparable survival compared with perioperative therapy in our data. Further prospective investigations of TNT are warranted.

Radiation Therapy for Rectal Cancer: Executive Summary of an ASTRO Clinical Practice Guideline

PURPOSE

This guideline reviews the evidence and provides recommendations for the indications and appropriate technique and dose of neoadjuvant radiation therapy (RT) in the treatment of localized rectal cancer.

METHODS

The American Society for Radiation Oncology convened a task force to address 4 key questions focused on the use of RT in preoperative management of operable rectal cancer. These questions included the indications for neoadjuvant RT, identification of appropriate neoadjuvant regimens, indications for consideration of a nonoperative or local excision approach after chemoradiation, and appropriate treatment volumes and techniques. Recommendations were based on a systematic literature review and created using a predefined consensus-building methodology and system for grading evidence quality and recommendation strength.

RESULTS

Neoadjuvant RT is recommended for patients with stage II-III rectal cancer, with either conventional fractionation with concurrent 5-FU or capecitabine or short-course RT. RT should be performed preoperatively rather than postoperatively. Omission of preoperative RT is conditionally recommended in selected patients with lower risk of locoregional recurrence. Addition of chemotherapy before or after chemoradiation or after short-course RT is conditionally recommended. Nonoperative management is conditionally recommended if a clinical complete response is achieved after neoadjuvant treatment in selected patients. Inclusion of the rectum and mesorectal, presacral, internal iliac, and obturator nodes in the clinical treatment volume is recommended. In addition, inclusion of external iliac nodes is conditionally recommended in patients with tumors invading an anterior organ or structure, and inclusion of inguinal and external iliac nodes is conditionally recommended in patients with tumors involving the anal canal.

CONCLUSIONS

Based on currently published data, the American Society for Radiation Oncology task force has proposed evidence-based recommendations regarding the use of RT for rectal cancer. Future studies will look to further personalize treatment recommendations to optimize treatment outcomes and quality of life.

Clinical Implementation of Preoperative Short-Course Pencil Beam Scanning Proton Therapy for Patients With Rectal Cancer

Purpose

For treatment of rectal cancer, pencil beam scanning proton therapy (PBS-PT) may reduce radiation exposure to normal tissues compared with 3-dimensional conformal photon radiation therapy (3DCRT) or volumetric modulated arc photon radiation therapy (VMAT). The purpose of this study was to report the clinical implementation and dosimetric analysis of preoperative short-course PBS-PT for rectal cancer.

Methods and Materials

Eleven patients with stage IIA-IVB rectal cancer received preoperative short-course (25 Gy in 5 fx) PBS-PT between 2018 and 2019 preceding curative-intent total mesorectal excision. PBS-PT plans were generated using single-field optimization with 2 posterior-oblique fields. Verification computed tomography scans were performed on the first 3 days of treatment. Each patient had a backup 3DCRT and VMAT plan.

Results

Clinical target volume coverage was similar between PBS-PT, 3DCRT, and VMAT. PBS-PT had statistically significant reductions in dose to the small bowel, large bowel, bladder, and femoral heads across multiple dosimetric parameters. All patients completed PBS-PT as planned without need for replanning. All computed tomography verification scans demonstrated good target coverage with clinical target volume V100 > 95%.

Conclusions

Preoperative short-course PBS-PT has been successfully implemented and offers a significant reduction of dose to normal tissues. Prospective studies are warranted to evaluate if dosimetric advantages translate into clinical benefit.

[Preoperative intensity-modulated radiotherapy of rectal cancers: Relevance and modalities]

Preoperative radiotherapy boosted by chemotherapy is a recommended treatment in locally advanced rectal cancers. This treatment is delivered by three dimensional conformal irradiation, which is usually well tolerated but can induce potential toxicity such as rectitis, cystitis and hematologic adverse effects. Intensity-modulated radiotherapy, widely available nowadays, allows optimization of volume covering and sparing of organs at risk such as bladder and bone marrow. This review presents relevant clinical situations and requirements for a beneficial and safe preoperative irradiation of rectal cancers by intensity-modulated technique. This technique is compared to three-dimensional conformal radiotherapy.

Dose-time fractionation schedules of preoperative radiotherapy and timing to surgery for rectal cancer

Chemoradiotherapy (CRT) is extensively used prior to surgery for rectal cancer to provide significantly better local control, but the radiotherapy (RT), as the other component of CRT, has been subject to less interest than the drug component in recent years. With considerable developments in RT, the use of advanced techniques, such as intensity-modulated radiotherapy (IMRT) in rectal cancer, is garnering more attention nowadays. The radiation dose can be better conformed to the target volumes with possibilities for synchronous integrated boost without increased complications in normal tissue. Hopefully, both local recurrence and toxicities can be further reduced. Although those seem to be of interest, many issues remain unresolved. There is no international consensus regarding the radiation schedule for preoperative RT for rectal cancer. Moreover, an enormous disparity exists regarding the RT delivery. With the advent of IMRT, variations will likely increase. Moreover, time to surgery is also quite variable, as it depends upon the indication for RT/CRT in the clinical practices. In this review, we discuss the options and problems related to both the dose-time fractionation schedule and time to surgery; furthermore, it addresses the research questions that need answering in the future.

Novel Radiotherapy Technologies in the Treatment of Gastrointestinal Malignancies

Over the past 2 decades, major technical advances in radiation therapy planning and delivery have made it possible to deliver higher doses to select high-risk volumes. This has helped to expand the role of radiation therapy in the treatment of gastrointestinal malignancies. Whereas dose escalation was previously limited by the radiosensitivity of normal tissues within and adjacent to the gastrointestinal tract, advances in target delineation, patient immobilization, treatment planning, and image-guided treatment delivery have greatly improved the therapeutic ratio. More conformal radiation modalities can offer further dose optimization to target volumes while sparing normal tissue from toxicity.

Impact of nominal photon energies on normal tissue sparing in knowledge-based radiotherapy treatment planning for rectal cancer patients

The interactive adjustment of the optimization objectives during the treatment planning process has made it difficult to evaluate the impact of beam quality exclusively in radiotherapy. Without consensus in the published results, the arbitrary selection of photon energies increased the probability of suboptimal plans. This work aims to evaluate the dosimetric impact of various photon energies on the sparing of normal tissues by applying a preconfigured knowledge-based planning (RapidPlan) model to various clinically available photon energies for rectal cancer patients, based on model-generated optimization objectives, which provide a comparison basis with less human interference. A RapidPlan model based on 81 historical VMAT plans for pre-surgical rectal cancer patients using 10MV flattened beam (10X) was used to generate patient-specific objectives for the automated optimization of other 20 patients using 6X, 8X, 10X (reference), 6MV flattening-filter-free (6F) and 10F beams respectively on a TrueBeam accelerator. It was observed that flattened beams produced very comparable target dose coverage yet the conformity index using 6F and 10F were clinically unacceptable (>1.29). Therefore, dose to organs-at-risk (OARs) and normal tissues were only evaluated for flattened beams. RapidPlan-generated objectives for 6X and 8X beams can achieve comparable target dose coverage as that of 10X, yet the dose to normal tissues increased monotonically with decreased energies. Differences were statistically significant except femoral heads. From the radiological perspective of view, higher beam energy is still preferable for deep seated tumors, even if multiple field entries such as VMAT technique can accumulate enough dose to the target using lower energies, as reported in the literature. In conclusion, RapidPlan model configured for flattened beams cannot optimize un-flattened beams before adjusting the target objectives, yet works for flattened beams of other energies. For the investigated 10X, 8X and 6X photons, higher energies provide better normal tissue sparing.

Safety and Efficacy of Hypofractionated Radiotherapy With Capecitabine in Elderly Patients With Urothelial Carcinoma

BACKGROUND

Bladder cancer is commonly diagnosed in patients ineligible for radical cystectomy or chemoradiotherapy (chemo-RT) with cisplatin or fluorouracil with mitomycin. We assessed tolerability, efficacy, and toxicity of hypofractionated radiotherapy with capecitabine in this challenging population.

PATIENTS AND METHODS

Patients with high-grade urothelial bladder cancer ineligible for radical cystectomy or high-intensity chemo-RT underwent maximal transurethral resection of bladder tumor followed by capecitabine (median, 825 mg/m² per day 2 times a day) and radiation (median, 55 Gy in 2.2 Gy per fraction). Patients underwent surveillance cystoscopy and imaging, and were evaluated for toxicity, freedom from local failure and freedom from distant metastasis, progression-free survival, and overall survival.

RESULTS

Eleven patients (median age, 80 years) with localized disease (n = 7), locally advanced disease (n = 3), or local-only recurrence after cystectomy (n = 1) were treated. Four patients (35%) had an Eastern Cooperative Oncology Group performance status of 2; median Charlson comorbidity index was 5. There was 1 acute grade 3 genitourinary event (9%), 6 acute grade 3 hematologic events (55%) of lymphopenia, and no acute grade 4 or higher events or hospitalizations. Ten patients (91%) completed radiotherapy, while 4 patients (36%) temporarily discontinued capecitabine. The complete response rate in the bladder was 64%. Two patients (18%) experienced late grade 1/2 genitourinary toxicities, and 1 (9%) experienced a transient late grade 4 genitourinary toxicity. With a median follow-up of 16.6 months, overall survival, progression-free survival, freedom from local failure, and freedom from distant metastasis at 1 year were 82%, 55%, 100%, and 55%, respectively, and at 2 years were 61%, 41%, 80%, and 55%, respectively.

CONCLUSION

Hypofractionated chemo-RT was well tolerated and was associated with a high rate of local control in this comorbid population, thus providing a treatment option for select bladder cancer patients.

A novel dynamic arc treatment planning solution to reduce dose to small bowel in preoperative radiotherapy for rectal cancer

Preoperative radiotherapy or combined chemoradiotherapy for locally advanced rectal cancer (LARC) can cause acute and late gastrointestinal (GI) side-effects. There is thought to be a dose-volume relationship between small bowel irradiation and the development of these effects. A planning study was undertaken to compare small bowel sparing for a range of 3D conformal and dynamic arc planning solutions. A planning study was carried out for 20 LARC patients. Organs at risk (OAR) contoured included bowel loops and peritoneal space (PS). For each of the 20 patients, 5 plans were created: (1) standard 3D conformal plan; (2) standard dual dynamic arc plan; (3) dual dynamic arc plan with 90° avoidance sector through the anterior portion of the patient; (4) dual dynamic arc plan with an anterior avoidance structure in the optimizer; (5) dual dynamic arc plan with both an anterior avoidance structure and an avoidance sector. The prescription was 50.4 Gy in 28 fractions to the planning target volume (PTV). Five Dose Volume Levels (DVLs; V_{15 Gy}, V_{20 Gy}, V_{25 Gy}, V_{35 Gy}, V_{40 Gy}, and V_{50.4 Gy}) for bowel and PS were selected. The DVLs were compared between the plans using Friedman Tests and Wilcoxon Signed Rank Tests. Comparison of the 5 plans revealed that a dual dynamic arc plan containing both an anterior avoidance sector and structure significantly improved the dose to the bowel compared to a standard 3D conformal plan and to a standard dual dynamic arc plan. This improvement was achieved while maintaining PTV coverage. This novel dual dynamic arc planning technique that uses both an avoidance sector and structure reduces the dose to the bowel and PS, which may lead to a reduction in GI toxicity.

Quality Control of Radiation Delivery for Lower Gastrointestinal Cancers

OPINION STATEMENT

Assessing the quality of health care delivered is a priority across medical specialties, but it is particularly critical for radiation oncology, a field with rapid introduction of new technologies and treatment paradigms. Deviation from acceptable standards can lead to delivery of inferior therapies and medical errors that can directly compromise patient clinical outcome, thus leading to disparities in quality of care. Professional oncologic specialty societies often take ownership of standardizing best practices by issuing evidence-based disease-specific consensus guidelines. They also inform quality indicators that are set as requirements for accreditation, maintenance of certification, and reimbursement. Cooperative groups also create benchmarks for quality radiation therapy through design of clinical protocols that set standard-of-care treatment practices. Pelvic radiotherapy for colorectal and anal cancers has undergone a significant transformation in radiation planning and delivery including increased complexity in contour segmentation with a transition from three-dimensional to intensity-modulated radiation therapy (IMRT). Compliance with quality metrics proposed in national consensus guidelines and participation in clinical trials help keep practicing radiation oncologists up-to-date with advances in our field and well-trained to provide safe and effective high-value care.

[Image-guided radiotherapy contribution and patient setup for anorectal cancer treatment]

Intensity-modulated radiation therapy is recommended in anal squamous cell carcinoma treatment and is increasingly used in rectal cancer. It adapts the dose to target volumes, with a high doses gradient. Intensity-modulated radiation therapy allows to reduce toxicity to critical normal structures and to consider dose-escalation studies or systemic treatment intensification. Image-guided radiation therapy is a warrant of quality for intensity-modulated radiation therapy, especially for successful delivery of the dose as planned. There is no recommended international or national anorectal cancer image-guided radiation therapy protocol currently available. Dose-escalation trials or expert opinions about intensity-modulated/image-guided radiation therapy good practice guidelines recommend daily volumetric imaging throughout the treatment or during the five first fractions and weekly thereafter as a minimum. Image-guided radiation therapy allows to reduce margins related to patient setup errors. Internal margin, related to the internal organ motion, needs to be adapted according to short- or long-course radiotherapy, gender, rectal location; it can be higher than current recommended planning target volume margins, particularly in the upper and anterior part of mesorectum, which has the most significant movement. Image-guided radiation therapy based on volumetric imaging allows to take target volume shrinkage into account and to develop adaptive strategies, in particular for mesorectum shrinkage during rectal cancer treatment. Lastly, the emergence of new image-guided radiation therapy technologies including MRI (which plays a major role in pelvic tumours assessment and diagnosis) opens up interesting perspectives for adaptive radiotherapy, taking into account both organs' movements and tumour shrinkage.

Neoadjuvant PET and MRI-based intensity modulated radiotherapy leads to less toxicity and improved pathologic response rates in locally advanced rectal cancer

Background

Neoadjuvant chemoradiation (NeoCRT) is standard of care for the treatment of locally advanced rectal cancer (LARC). Contemporary radiation techniques and pre-treatment imaging may impact toxicities and pathologic response (PR). Herein we compare intensity modulated radiotherapy (IMRT) and advanced pre-treatment imaging in the neoadjuvant treatment of LARC and resulting impact on toxicities and pathologic outcomes relative to 3 dimensional conformal radiotherapy (3DCRT).

Methods

LARC patients treated at 4 large academic centers in the US from 2007-2016 were reviewed. Patients received 5-FU-based NeoCRT concurrently with IMRT or 3DCRT. PR was recorded as none, partial, or complete. Common terminology for adverse events version 4 was used to grade toxicities. Toxicity rates were compared using Chi-square analysis. Multivariable models were fit adjusting for age, gender, pre-tx CT to identify independent predictors of PR and toxicity.

Results

A total of 128 patients were analyzed: 60.1% male and 39.8% female, median age 57.7 years (range, 31-85 years). Clinical characteristics were similar across RT groups. The outcome of partial and complete PR was similar for IMRT and 3DCRT (48.1%, 23.1% vs. 31.7%, 23.3%), respectively. After adjusting for gender, age, and pre-RT chemotherapy type, IMRT and pretreatment PET and/or MRI imaging was significantly associated with increased odds for complete and partial response (OR =2.95, 95% CI: 1.21-7.25, P=0.018; OR =14.70, 95% CI: 3.69-58.78, P<0.0001). Additionally, IMRT was associated with reduced rates of dehydration, dermatitis, rectal pain, rectal bleeding, and diverting ostomy (P<0.05). Overall rates of grade 2 and higher toxicities were significantly reduced in IMRT vs. 3DCRT after adjusting for confounders (OR =0.27, 95% CI: 0.08-0.87).

Conclusions

NeoCRT IMRT with pretreatment PET and/or MRI for LARC leads to reduced acute toxicities and improved PR compared to 3DCRT. Given the challenges associated with prospective validation of these data, IMRT with pretreatment PET and/or MRI should be considered standard treatment for LARC.

Magnetic Resonance-guided Inter-fraction Monitoring Opens Doors to Delivering Safer Reirradiation: An Illustrative Case Report and Discussion

Locoregional recurrence in the pelvis after definitive treatment for rectal cancer can lead to significant morbidity. Furthermore, the toxicity associated with reirradiation may also negatively impact the quality of life and even survival. Here we present the case of a 39-year-old male with locoregionally recurrent rectal cancer in a left pelvic sidewall lymph node, treated with stereotactic magnetic resonance (MR)-guided ablative radiotherapy after previously receiving long-course chemoradiation that had already exceeded ideal bowel dose constraints. We discuss the distinct advantages of MR-guidance in the setting of pelvic reirradiation, particularly with regard to inter- and intra-fraction visualization of the target and neighboring bowel anatomy. In this context, MR-guidance may allow radiation oncologists to increase target precision and accuracy, while simultaneously decreasing toxicity to neighboring tissues.

Prospective study of neoadjuvant chemoradiotherapy using intensity-modulated radiotherapy and 5 fluorouracil for locally advanced rectal cancer - toxicities and response assessment

Aims and objectives

The past 2 decades witnessed the strengthening of evidence favoring the role of neoadjuvant chemoradiation (CHRT) in the treatment of locally advanced rectal cancer. The study aims to evaluate the response and acute toxicities to neoadjuvant CHRT using intensity-modulated radiotherapy (IMRT) in the treatment of rectal cancer. Predictive factors to achieve pathological complete response (pCR) were analyzed, as a secondary endpoint.

Materials and methods

All consecutive patients who underwent IMRT as part of neoadjuvant CHRT in the treatment of rectal cancer between August 2014 and December 2016 at a tertiary cancer care center were accrued for the study. The cohort underwent CHRT with IMRT technique at a dose of 50.4 Gy in 28 fractions concurrent with continuous infusion of 5 fluorouracil during the first and the last 4 days of CHRT. Surgery was performed 6 weeks later and the pathological response to CHRT was noted.

Results

Forty-three subjects were accrued for the study. Radiation dermatitis and diarrhea were the only observed grade ≥3 acute toxicities. Sphincter preservation rate (SPR) was 43.3%. pCR was observed in 32.6%. Univariate and multivariate logistic regression showed that carcinoembryonic antigen was the only independent predictive factor to achieve pCR.

Conclusion

IMRT as part of neoadjuvant CHRT in the treatment of locally advanced rectal cancer is well tolerated and gives comparable results with respect to earlier studies in terms of pathological response and SPR. Further randomized controlled studies are needed to firmly state that IMRT is superior to 3-dimensional conformal radiotherapy.

Preoperative Intensity-modulated Chemoradiation Therapy with Simultaneous Integrated Boost in Rectal Cancer: 2-year Follow-up Results of Phase II Study

Background

The aim of the study was to investigate the feasibility and safety of experimental fractionation using intensity modulated radiation therapy with a simultaneous integrated boost (IMRT-SIB) to shorten the overall treatment time without dose escalation in preoperative radiochemotherapy of locally advanced rectal cancer.

Patients and methods

Between January 2014 and November 2015, a total of 51 patients with operable stage II-III rectal adenocarcinoma were treated. The preoperative treatment with intensity modulated radiation therapy (IMRT) and a pelvic dose of 41.8 Gy and simultaneously delivered 46.2 Gy to T2/3 and 48.4 Gy to T4 tumour in 22 fractions, with standard concomitant capecitabine, was completed in 50 patients out of whom 47 were operated. The median follow-up was 35 months.

Results

The rate of acute toxicity G ≥ 3 was 2.4%. The total downstaging rate was 89% and radical resection was achieved in 98% of patients. Pathologic complete response (pCR) was observed in 25.5% of patients, with 2-year local control (LC), disease free survival (DFS), and overall survival (OS) of 100% for this patient group. An intention-to-treat analysis revealed pN to be a significant prognostic factor for DFS and OS (P = 0.005 and 0.030, respectively). LC for the entire group was 100%, and 2-year DFS and OS were 90% (95 % CI 98.4–81.6) and 92.2% (95% CI 99.6–84.7), respectively.

Conclusions

The experimental regime in this study resulted in a high rate of pCR with a low acute toxicity profile. Excellent early results translated into encouraging 2-year LC, DFS, and OS.

Neoadjuvant Treatment Strategies: Advanced Radiation Alternatives

Long-course chemoradiation therapy (CRT) has been the standard approach for locally advanced rectal tumors. Neoadjuvant CRT is associated to improved local disease control, with less toxicity when compared with adjuvant CRT, as well as the chance for pathologic complete response. The CRT regimens have improved over the past years. This article will examine selected controversies, including novel chemoradiation regimens, duration of radiation (short vs. long course), and radiation techniques such as intensity-modulated radiation therapy (IMRT).

Current issues of preoperative radio(chemo)therapy and its future evolution in locally advanced rectal cancer

Neoadjuvant therapies are effective for local control and tumor downstaging. Up to date, preoperative long-course chemoradiotherapy and short-course radiotherapy are the two primary guideline-recommended neoadjuvant therapies for locally advanced rectal cancer patients. However, clinicians throughout the world are trying their best to further optimize the regimens and concepts of neoadjuvants. Hence, there is an urgent need to summarize evidence regarding indications of neaoadjuvant therapies and relative merits of current standard regimens. In addition, we also reviewed the optimized regimens mainly based on short-course radiotherapy with delayed surgery, consolidation chemotherapy, induction chemotherapy, chemotherapy alone without radiation and concepts in terms of organ preservation and personalized treatments to further explore the future evolution of neoadjuvant therapies in rectal cancer.

Simultaneous integrated boost intensity-modulated radiotherapy versus 3-dimensional conformal radiotherapy in preoperative concurrent chemoradiotherapy for locally advanced rectal cancer

Purpose

To evaluate the feasibility of simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) for preoperative concurrent chemoradiotherapy (PCRT) in locally advanced rectal cancer (LARC), by comparing with 3-dimensional conformal radiotherapy (3D-CRT).

Materials and Methods

Patients who were treated with PCRT for LARC from 2015 January to 2016 December were retrospectively enrolled. Total doses of 45 Gy to 50.4 Gy with 3D-CRT or SIB-IMRT were administered concomitantly with 5-fluorouracil plus leucovorin or capecitabine. Surgery was performed 8 weeks after PCRT. Between PCRT and surgery, one cycle of additional chemotherapy was administered. Pathologic tumor responses were compared between SIB-IMRT and 3D-CRT groups. Acute gastrointestinal, genitourinary, hematologic, and skin toxicities were compared between the two groups based on the RTOG toxicity criteria.

Results

SIB-IMRT was used in 53 patients, and 3D-CRT in 41 patients. After PCRT, no significant differences were noted in tumor responses, pathologic complete response (9% vs. 7%; p = 1.000), pathologic tumor regression Grade 3 or higher (85% vs. 71%; p = 0.096), and R0 resection (87% vs. 85%; p = 0.843). Grade 2 genitourinary toxicities were significantly lesser in the SIB-IMRT group (8% vs. 24%; p = 0.023), but gastrointestinal toxicities were not different across the two groups.

Conclusion

SIB-IMRT showed lower GU toxicity and similar tumor responses when compared with 3D-CRT in PCRT for LARC.

Trends in intensity modulated radiation therapy use for locally advanced rectal cancer at National Comprehensive Cancer Network centers

Purpose

Intensity modulated radiation therapy (IMRT) has been rapidly incorporated into clinical practice because of its technological advantages over 3-dimensional conformal radiation therapy (CRT). We characterized trends in IMRT utilization in trimodality treatment of locally advanced rectal cancer at National Comprehensive Cancer Network cancer centers between 2005 and 2011.

Methods and materials

Using the prospective National Comprehensive Cancer Network Colorectal Cancer Database, we determined treatment patterns for 976 patients with stage II-III rectal cancer who received pelvic radiation therapy at contributing centers between 2005 and 2011. Multivariable logistic regression was used to identify factors associated with IMRT versus 3-dimensional CRT. Radiation therapy compliance and time to completion were used to compare acute toxicity.

Results

A total of 947 patients (97%) received 3-dimensional CRT (80%) or IMRT (17%). Ninety-eight percent of these patients received radiation therapy preoperatively, and 81% underwent definitive resection. IMRT use increased from <13% pre-2009 to >30% in 2010 and thereafter, with significant variability among institutions (range, 0%-43%). Other factors associated with IMRT use included age ≥65 years, dose >50.4 Gy, African-American race, and no transabdominal surgery. Rates of and time to radiation therapy completion were similar between the groups.

Conclusions

Although most patients with stage II-III rectal cancer at queried National Cancer Institute–designated cancer centers between 2005 and 2011 received 3-dimensional CRT, significant and increasing numbers received IMRT. IMRT utilization is highly variable among institutions and not uniform among sociodemographic groups but may be more consistently embraced in specific clinical settings. Given this trend, comparative-effectiveness research is needed to evaluate the benefits of IMRT for rectal cancer.