Dose-Effect Relationship in Chemoradiotherapy for Locally Advanced Rectal Cancer: A Randomized Trial Comparing Two Radiation Doses

ACO/ARO/AIO-22 - External beam radiotherapy combined with endorectal high-dose-rate brachytherapy in elderly and frail patients with rectal cancer: A prospective multicentre trial of the German Rectal Cancer Study Group

Purpose

Rectal cancer disproportionately affects the elderly population, with more than half of cases diagnosed in individuals aged 70 years or older. Frail patients in this group often face significant challenges tolerating the standard treatment of total mesorectal excision (TME), due to elevated risks of surgical complications and perioperative morbidity. Advances in radiotherapy techniques offer a viable alternative, providing effective tumor control while minimizing treatment-related toxicity. Recent clinical trials, including OPERA and MORPEUS, have demonstrated that dose-escalated radiotherapy, which integrates external beam (chemo)radiotherapy (EBRT) with high-dose-rate endorectal brachytherapy (HDR-BT) or contact X-ray brachytherapy (CXB), can achieve high clinical response rates and facilitate organ preservation in younger, healthier patient cohorts. Building on these findings, the ACO/ARO/AIO-22 study seeks to adapt these innovative approaches to meet the needs of elderly and frail patients with rectal cancer.

Methods/Design

The ACO/ARO/AIO-22 trial is a prospective multicentre controlled trial. Elderly (age ≥70 years) and/or frail patients with non-metastatic rectal adenocarcinoma (cT1-3d N0/+ M0, mrCRM - / +) localized 0-16 cm from the ano-cutaneous line, unable to undergo radical surgery can be included. The initial treatment comprises an external beam radiation (EBRT) regime with 13 × 3 Gy (total: 39 Gy) over a period of two and a half weeks. Following initial restaging 6.5 weeks after completion of EBRT, endorectal HDR-BT will be delivered with 3 weekly fractions of 8 Gy to a total dose of 24 Gy (prescribed at the radial margin of the tumor; with a maximum prescription depth of 10 mm); alternatively, with CXB with 90 Gy in 3 weekly fractions. The primary objective is complete or near complete clinical response (cCR or ncCR) and the second primary endpoint is quality of life (QoL) measured with the EORTC QLQ-ELD14, both at 12 months after treatment start.

Discussion

The ACO/ARO/AIO-22 prospective multicentre trial will evaluate organ preservation rates and QoL after combining EBRT with endorectal HDR-BT in elderly and/or frail patients with rectal cancer.Trial Registration:Clinicialtrials.gov number: NCT06729645.

Brachytherapy for rectal and anal cancer: Where are we and current perspectives?

Anal and rectal cancers were some of the first disease sites treated with brachytherapy due to the anatomic ease of implantation. As external beam radiotherapy grew in popularity the use of ano-rectal brachytherapy declined. However, the past few years have seen a steady resurgence in the use of brachytherapy in the ano-rectum supported by the use of large clinical series and randomized trials. The increasing acceptance by the surgical community of organ preservation as a valid treatment strategy for rectal cancer has encouraged the use of nonsurgical approaches and brachytherapy has shown itself to be a valuable tool for this. The current role of anal and rectal brachytherapy is presented with perspectives on its future use.

Results of a diagnostic imaging audit in a randomised clinical trial in rectal cancer highlight the importance of careful planning and quality control

BACKGROUND

Magnetic resonance (MR) imaging is the modality used for baseline assessment of locally advanced rectal cancer (LARC) and restaging after neoadjuvant treatment. The overall audited quality of MR imaging in large multicentre trials on rectal cancer is so far not routinely reported.

MATERIALS AND METHODS

We collected MR images obtained within the Rectal Cancer And Pre-operative Induction Therapy Followed by Dedicated Operation (RAPIDO) trial and performed an audit of the technical features of image acquisition. The required MR sequences and slice thickness stated in the RAPIDO protocol were used as a reference.

RESULTS

Out of 920 participants of the RAPIDO study, MR investigations of 668 and 623 patients in the baseline and restaging setting, respectively, were collected. Of these, 304/668 (45.5%) and 328/623 (52.6%) MR images, respectively, fulfilled the technical quality criteria. The main reason for non-compliance was exceeding slice thickness 238/668, 35.6% in the baseline setting and 162/623, 26.0% in the restaging setting. In 166/668, 24.9% and 168/623, 27.0% MR images in the baseline and restaging setting, respectively, one or more of the required pulse sequences were missing.

CONCLUSION

Altogether, 49.0% of the MR images obtained within the RAPIDO trial fulfilled the image acquisition criteria required in the study protocol. High-quality MR imaging should be expected for the appropriate initial treatment and response evaluation of patients with LARC, and efforts should be made to maximise the quality of imaging in clinical trials and in clinical practice.

CRITICAL RELEVANCE STATEMENT

This audit highlights the importance of adherence to MR image acquisition criteria for rectal cancer, both in multicentre trials and in daily clinical practice. High-resolution images allow correct staging, treatment stratification and evaluation of response to neoadjuvant treatment.

KEY POINTS

- Complying to MR acquisition guidelines in multicentre trials is challenging. - Neglection on MR acquisition criteria leads to poor staging and treatment. - MR acquisition guidelines should be followed in trials and clinical practice. - Researchers should consider mandatory audits prior to study initiation.

Radiotherapy in the preoperative neoadjuvant treatment of locally advanced rectal cancer

Radiotherapy and chemotherapy are effective treatments for patients with locally advanced rectal cancer (LARC) and can significantly improve the likelihood of R0 resection. Radiotherapy can be used as a local treatment to reduce the size of the tumor, improve the success rate of surgery and reduce the residual cancer cells after surgery. Early chemotherapy can also downgrade the tumor and eliminate micrometastases throughout the body, reducing the risk of recurrence and metastasis. The advent of neoadjuvant concurrent radiotherapy (nCRT) and total neoadjuvant treatment (TNT) has brought substantial clinical benefits to patients with LARC. Even so, given increasing demand for organ preservation and quality of life and the disease becoming increasingly younger in its incidence profile, there is a need to further explore new neoadjuvant treatment options to further improve tumor remission rates and provide other opportunities for patients to choose watch-and-wait (W&W) strategies that avoid surgery. Targeted drugs and immunologic agents (ICIs) have shown good efficacy in patients with advanced rectal cancer but have not been commonly used in neoadjuvant therapy for patients with LARC. In this paper, we review several aspects of neoadjuvant therapy, including radiation therapy and chemotherapy drugs, immune drugs and targeted drugs used in combination with neoadjuvant therapy, with the aim of providing direction and thoughtful perspectives for LARC clinical treatment and research trials.

High-dose rate endorectal brachytherapy for rectal cancer: A state-of-the-art review

Rectal cancer is a common malignancy that requires multidisciplinary treatment. By utilizing the dose-response relationship in rectal cancer radiotherapy, increasing the radiotherapy dose can improve clinical complete remission rates. High-dose rate endorectal brachytherapy (HDREBT) is a novel technique that delivers high doses of radiotherapy directly to the tumor via an endorectal applicator, sparing the adjacent normal tissues from excessive radiation exposure. HDREBT includes contact X-ray brachytherapy and high-dose-rate intracavitary brachytherapy. We introduce the latest developments in applicators and imaging techniques for HDREBT in rectal cancer and summarize the current evidence on the efficacy, safety, and feasibility of HDREBT as a neoadjuvant, definitive, or palliative treatment option for all stages of rectal cancer patients. We also discuss the potential advantages and challenges of HDREBT in achieving organ preservation and improving the quality of life of rectal cancer patients. HDREBT has shown promising results in achieving high complete response rates, enabling nonoperative management, improving organ preservation rates, and providing effective palliation in rectal cancer patients. More studies are needed to optimize its dose and fractionation schemes in different clinical scenarios.

Circumferential Resection Margin as Predictor of Nonclinical Complete Response in Nonoperative Management of Rectal Cancer

BACKGROUND

Short-course radiation therapy and consolidation chemotherapy with nonoperative intent has emerged as a novel treatment paradigm for patients with rectal cancer, but there are no data on the predictors of clinical complete response.

OBJECTIVE

Evaluate the predictors of clinical complete response and survival.

DESIGN

Retrospective cohort.

SETTINGS

National Cancer Institute-designated cancer center.

PATIENTS

Patients with stage I to III rectal adenocarcinoma treated between January 2018 and May 2019 (n = 86).

INTERVENTIONS

Short-course radiation therapy followed by consolidation chemotherapy.

MAIN OUTCOME MEASURES

Logistic regression was performed to assess for predictors of clinical complete response. The end points included local regrowth-free survival, regional control, distant metastasis-free survival, and overall survival.

RESULTS

A positive (+) circumferential resection margin by MRI at diagnosis was a significant predictor of nonclinical complete response (OR: 4.1, p = 0.009) when adjusting for CEA level and primary tumor size. Compared to patients with a negative (-) pathologic circumferential resection margin, patients with a positive (+) pathologic circumferential resection margin had inferior local regrowth-free survival (29% vs 87%, p < 0.001), regional control (57% vs 94%, p < 0.001), distant metastasis-free survival (43% vs 95%, p < 0.001), and overall survival (86% vs 95%, p < 0.001) at 2 years. However, the (+) and (-) circumferential resection margin by MRI subgroups in patients who had a clinical complete response both had similar regional control, distant metastasis-free survival, and overall survival of more than 90% at 2 years.

LIMITATIONS

Retrospective design, modest sample size, short follow-up, and the heterogeneity of treatments.

CONCLUSIONS

Circumferential resection margin involvement by MRI at diagnosis is a strong predictor of nonclinical complete response. However, patients who achieve a clinical complete response after short-course radiation therapy and consolidation chemotherapy with nonoperative intent have excellent clinical outcomes regardless of the initial circumferential resection margin status. See Video Abstract at http://links.lww.com/DCR/C190 .

EL MARGEN DE RESECCIN CIRCUNFERENCIAL COMO PREDICTOR NO CLNICO DE RESPUESTA COMPLETA EN EL MANEJO CONSERVADOR DEL CNCER DE RECTO

ANTECEDENTES:La radioterapia de corta duración y la quimioterapia de consolidación en el manejo conservador, han surgido como un nuevo paradigma de tratamiento, para los pacientes con cáncer de recto, lastimosamente no hay datos definitivos sobre los predictores de una respuesta clínica completa.OBJETIVO:Evaluar los predictores de respuesta clínica completa y de la sobrevida.DISEÑO:Estudio retrospectivo de cohortes.AJUSTES:Centro oncológico designado por el NCI.PACIENTES:Adenocarcinomas de recto estadio I-III tratados entre 01/2018 y 05/2019 (n = 86).INTERVENCIONES:Radioterapia de corta duración seguida de quimioterapia de consolidación.PRINCIPALES MEDIDAS DE RESULTADO:Se realizó una regresión logística para evaluar los predictores de respuesta clínica completa. Los criterios de valoración incluyeron la sobrevida libre de recidiva local, el control regional, la sobrevida libre de metástasis a distancia y la sobrevida general.RESULTADOS:Un margen de resección circunferencial positivo (+) evaluado por imagenes de resonancia magnética nuclear en el momento del diagnóstico fue un predictor no clínico muy significativo de respuesta completa (razón de probabilidades/ OR: 4,1, p = 0,009) al ajustar el nivel de antígeno carcinoembrionario y el tamaño del tumor primario. Comparando con los pacientes que presetaban un margen de resección circunferencial patológico negativo (-), los pacientes con un margen de resección circunferencial patológico positivo (+) tuvieron una sobrevida libre de recidiva local (29% frente a 87%, p < 0,001), un control regional (57% frente a 94%, p < 0,001), una sobrevida libre de metástasis a distancia (43% frente a 95%, p < 0,001) y una sobrevida global (86% frente a 95%, p < 0,001) inferior en 2 años de seguimiento. Sin embargo, los subgrupos de margen de resección circunferencial (+) y (-) evaluados por imágenes de resonancia magnética nuclear en pacientes que tuvieron una respuesta clínica completa tuvieron un control regional similar, una sobrevida libre de metástasis a distancia y una sobrevida general >90% en 2 años de seguimiento.LIMITACIONES:Diseño retrospectivo, tamaño modesto de la muestra, seguimiento corto y heterogeneidad de tratamientos.CONCLUSIONES:La afectación del margen de resección circunferencial evaluado por resonancia magnética nuclear al momento del diagnóstico es un fuerte factor predictivo no clínico de respuesta completa. Sin embargo, los pacientes que logran una respuesta clínica completa después de un curso corto de radioterapia y quimioterapia de consolidación como manejo conservador tienen excelentes resultados clínicos independientemente del estado del margen de resección circunferencial inicial. Consulte Video Resumen en http://links.lww.com/DCR/C190 . (Traducción-Dr. Xavier Delgadillo ).

Organ and Function Preservation in Gastrointestinal Malignancies

Radiation plays an important role in organ preservation for gastrointestinal malignancies, with a watch and wait strategy enabling surgery to be avoided in patients who are not suitable or who are refusing surgery. Brachytherapy boost allows the radiation dose to be escalated, which plays a pivotal role in the successful outcome of achieving organ preservation. Here we describe the role of brachytherapy in two common gastrointestinal malignancies (oesophagus and rectum). Their indications and how the brachytherapy procedures are carried out, together with the dose and fractionation commonly used are discussed. The use of brachytherapy needs to be included in the training curriculum at all academic centres so that its use is developed by the newer generation of radiation oncologists. Its current non-use due to bias, lack of training and availability is no longer justified, given the overwhelming published evidence for the role of brachytherapy to improve organ preservation for both radical treatment and palliation in gastrointestinal malignancies.

Circulating tumour DNA in the evolving treatment landscape of locally advanced rectal cancer: where does it fit in?

The management of locally advanced rectal cancer (LARC) requires multimodality treatment, typically with neoadjuvant chemoradiotherapy (CRT) followed by total mesorectal excision. However, the treatment landscape is rapidly evolving with total neoadjuvant therapy and non-operative management for selected patients emerging as other novel treatment approaches. With so many treatment options, there is a need for biomarkers to direct a more personalised treatment strategy for patients with LARC. In this review, we summarise the available data regarding the use of circulating tumour DNA (ctDNA) in patients with LARC, as both a marker of treatment response to neoadjuvant therapy and as a marker of minimal residual disease (MRD) after patients have completed definitive local treatment. To date, the ability of ctDNA status to predict for pathologic complete response at any timepoint during multimodality treatment has been variably reported. The most consistent finding across available studies is the ability of ctDNA to detect MRD after CRT and surgery, the presence of which confers a significantly poor prognosis, with increased risk of cancer recurrence and worse overall survival. It is yet to be determined if providing additional therapies to patients with MRD improves outcomes. The available studies assessing the potential utility of ctDNA in LARC are limited by significant heterogeneity in the choice of ctDNA assay, timepoint at which ctDNA was collected, treatment that patients received and length of follow-up, leading to uncertainties about how to implement it into daily clinical practice. As the treatment landscape evolves, larger randomised trials assessing the role of ctDNA in LARC are needed.

Radiotherapy dose escalation using endorectal brachytherapy in elderly and frail patients with rectal cancer unsuitable for surgery: Lessons from studies in fit patients and future perspectives

Epidemiological data indicate that more than 50 % of patients with newly-diagnosed rectal cancer are older than 70 years, with rising numbers expected over the next decades. Treatment decision-making is challenging in elderly and frail patients with rectal cancer, whereas standardized treatment guidelines for this patient cohort are lacking. Elderly and frail rectal cancer patients are often considered by surgeons as unfit to undergo radical surgery as the risk of surgical complications and postoperative mortality rises with increasing age and comorbidity. Furthermore, these patients often receive no treatment at all, resulting in local and/or systemic disease progression with associated symptoms and impaired quality of life (QoL). Recent data from randomized trials in young fit patients with early stage rectal cancer indicate that RT dose escalation can be safely delivered using external beam (chemo)radiotherapy (EBRT) followed by endoluminal radiotherapeutic modalities, such as contact X-ray brachytherapy (CXB) or high-dose rate endorectal brachytherapy (HDR-BT). However, prospective studies testing this therapeutic concept in elderly and frail patients remain limited. Here, we review the current evidence in the epidemiology and the management of elderly and frail patients with rectal cancer. We summarize the potential of RT dose escalation to achieve long-term local control of the primary tumour, prevent disease-related morbidity, improve QoL and even organ preservation. Future perspectives and open questions will be discussed as well.

Efficacy and safety of different radiotherapy doses in neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer: A retrospective study

Background

This study aims to compare the efficacy and safety of neoadjuvant chemoradiotherapy (nCRT) with different radiotherapy doses (45Gy and 50.4Gy) in patients with locally advanced rectal cancer (LARC).

Methods

Herein, 120 patients with LARC were retrospectively enrolled between January 2016 and June 2021. All patients underwent two courses of induction chemotherapy (XELOX), chemoradiotherapy, and total mesorectum excision (TME). A total of 72 patients received a radiotherapy dose of 50.4 Gy, while 48 patients received a dose of 45 Gy. Surgery was then performed within 5-12 weeks following nCRT.

Results

There was no statistically significant difference between the baseline characteristics of the two groups. The rate of good pathological response in the 50.4Gy group was 59.72% (43/72), while in the 45Gy group achieved 64.58% (31/48) (P>0.05). The disease control rate (DCR) in the 50.4Gy group was 88.89% (64/72), compared to 89.58% (43/48) in the 45Gy group (P>0.05). The incidence of adverse reactions for radioactive proctitis, myelosuppression, and intestinal obstruction or perforation differed significantly between the two groups (P<0.05). The anal retention rate in the 50.4Gy group was significantly higher in contrast to the 45Gy group (P<0.05).

Conclusions

Patients receiving a radiotherapy dose of 50.4Gy have a better anal retention rate but also a higher incidence of adverse events such as radioactive proctitis, myelosuppression, and intestinal obstruction or perforation, and a comparable prognosis to patients treated with a radiotherapy dose of 45Gy.

Predictors of Definitive Treatment Interruptions of Long-Course Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer

Introduction To identify predictors of definitive treatment interruptions (DTI) of the neoadjuvant long-course radiotherapy (LCRT) in locally advanced rectal cancer (LARC), and to determine their impact on clinical outcomes. Methods Patients with stage II-III LARC treated between 2009-2018 were retrospectively analyzed (n=101, median FU 49.5 months). Logistic regression models evaluated the impact of relevant clinical variables on grade 3 or greater (G3+) acute toxicity, definitive treatment interruption (DTI), pCR, and definitive ostomy (dOST) rates. The secondary outcomes were LRC, MFS, PFS, CSS, and OS. Results The incidences of grade 3 and 4 toxicities were 25.3%, and 1.1%, respectively. The most common G3+ toxicities were peri-anal dermatitis (14.7%) and diarrhea (7.4%), which were more frequent in females (p=0.040) and tumors close to the anal verge (p=0.019). In this study, 11 patients (10.9%) developed DTI, which was associated with these G3+ events (p<0.001). Resection occurred after 7.1 weeks (median, IQR:6.1-8.9). Downstaging occurred in 57.4% (17.8% pCR), 88% achieved negative margins and the dOST rate was 56.4%. The five-year LRC, MFS, PFS, CSS and OS were: 94.4%, 78.9%, 74.7%, 85.2% and 81.6%, respectively. DTI events did not impact any outcome. The factors associated with loco-regional failure were close/positive margins (p<0.001) and stage ypIII (p=0.002). Conclusions: Tumors close to the anal verge and female sex were associated with increased G3+ toxicity, which was predictive of DTI. The resultant partial/complete omission of the planned boost, however, dose did not increase the chance of LR. Further studies to clarify the benefit and optimal timing to deliver the boost are warranted, especially for positive margins.

MORPHEUS Phase II–III Study: A Pre-Planned Interim Safety Analysis and Preliminary Results

Background: We explored image-guided adaptive endorectal brachytherapy patients electing non-operative management for rectal cancer. We present the first pre-planned interim analysis. Methods: In this open-label phase II–III randomized study, patients with operable cT2-3ab N0 M0 rectal cancer received 45 Gy in 25 fractions of pelvic external beam radiotherapy (EBRT) with 5-FU/Capecitabine. They were randomized 1:1 to receive either an EBRT boost of 9 Gy in 5 fractions (Arm A) or three weekly adaptive brachytherapy (IGAEBT) boosts totaling 30 Gy (Arm B). Patient characteristics and toxicity are presented using descriptive analyses; TME-free survival between arms with the intention to treat the population is explored using the Kaplan–Meier method. Results: A total of 40 patients were in this analysis. Baseline characteristics were balanced; acute toxicities were similar. Complete clinical response (cCR) was 50% (n = 10/20) in Arm A and 90% in Arm B (n = 18/20). Median follow-up was 1.3 years; 2-year TME-free survival was 38.6% (95% CI: 16.5–60.6%) in the EBRT arm and 76.6% (95% CI: 56.1–97.1%) in the IGAEBT arm. Conclusions: Radiation intensification with IGAEBT is feasible. This interim analysis suggests an improvement in TME-free survival when comparing IGAEBT with EBRT, pending confirmation upon completion of this trial.

A Multidisciplinary Approach for the Personalised Non-Operative Management of Elderly and Frail Rectal Cancer Patients Unable to Undergo TME Surgery

Despite it being the optimal curative approach, elderly and frail rectal cancer patients may not be able to undergo a total mesorectal excision. Frequently, no treatment is offered at all and the natural course of the disease is allowed to unfold. These patients are at risk for developing debilitating symptoms that impair quality of life and require palliative treatment. Recent advancements in non-operative treatment modalities have enhanced the toolbox of alternative treatment strategies in patients unable to undergo surgery. Therefore, a proposed strategy is to aim for the maximal non-operative treatment, in an effort to avoid the onset of debilitating symptoms, improve quality of life, and prolong survival. The complexity of treating elderly and frail patients requires a patient-centred approach to personalise treatment. The main challenge is to optimise the balance between local control of disease, patient preferences, and the burden of treatment. A comprehensive geriatric assessment is a crucial element within the multidisciplinary dialogue. Since limited knowledge is available on the optimal non-operative treatment strategy, these patients should be treated by dedicated multidisciplinary rectal cancer experts with special interest in the elderly and frail. The aim of this narrative review was to discuss a multidisciplinary patient-centred treatment approach and provide a practical suggestion of a successfully implemented clinical care pathway.

The "Immunoscore" in rectal cancer: could we search quality beyond quantity of life?

Because of the function and anatomical environment of the rectum, therapeutic strategies for local advanced rectal cancer (LARC) must deal with two challenging stressors that are a high-risk of local and distal recurrences and a high-risk of poor quality of life (QoL). Over the last three decades, advances in screening tests, therapies, and combined-modality treatment options and strategies have improved the prognosis of patients with LARC. However, owing to the heterogeneous nature of LARC and genetic status, the patient may not respond to a specific therapy and may be at increased risk of side-effects without the life-prolonging benefit. Indeed, each therapy can cause its own side-effects, which may worsen by a combination of treatments resulting in long-term poor QoL. In LARC, QoL has become even more essential with the increasing incidence of rectal cancer in young individuals. Herein, we analyzed the value of the Immunoscore-Biopsy (performed on tumor biopsy at diagnosis) in predicting outcomes, alone or in association with clinical and imaging data, for each therapy used in LARC.

Recent advances in (chemo-)radiation therapy for rectal cancer: a comprehensive review

The role of radiation therapy in the treatment of (colo)-rectal cancer has changed dramatically over the past decades. Introduced with the aim of reducing the high rates of local recurrences after conventional surgery, major developments in imaging, surgical technique, systemic therapy and radiation delivery have now created a much more complex environment leading to a more personalized approach. Functional aspects including reduction of acute or late treatment-related side effects, sphincter or even organ-preservation and the unsolved problem of still high distant failure rates have become more important while local recurrence rates can be kept low in the vast majority of patients. This review summarizes the actual role of radiation therapy in different subgroups of patients with rectal cancer, including the current standard approach in different subgroups as well as recent developments focusing on neoadjuvant treatment intensification and/or non-operative treatment approaches aiming at organ-preservation.

Modeling precision genomic-based radiation dose response in rectal cancer

Aim: Genomic-based risk stratification to personalize radiation dose in rectal cancer. Patients & methods: We modeled genomic-based radiation dose response using the previously validated radiosensitivity index (RSI) and the clinically actionable genomic-adjusted radiation dose. Results: RSI of rectal cancer ranged from 0.19 to 0.81 in a bimodal distribution. A pathologic complete response rate of 21% was achieved in tumors with an RSI <0.31 at a minimal genomic-adjusted radiation dose of 29.76 when modeling RxRSI to the commonly prescribed physical dose of 50 Gy. RxRSI-based dose escalation to 55 Gy in tumors with an RSI of 0.31-0.34 could increase pathologic complete response by 10%. Conclusion: This study provides a theoretical platform for development of an RxRSI-based prospective trial in rectal cancer.

Neoadjuvant Radiotherapy Dose Escalation in Locally Advanced Rectal Cancer: a Systematic Review and Meta-analysis of Modern Treatment Approaches and Outcomes

AIMS

Improving pathological complete response (pCR) rates after neoadjuvant chemoradiotherapy for locally advanced rectal cancer may facilitate surgery-sparing treatment paradigms. Radiotherapy boost has been linked to higher rates of pCR; however, outcomes in moderately escalated inverse-planning studies have not been systematically evaluated. We therefore carried out a systematic review and meta-analysis of radiation dose-escalation studies in the context of neoadjuvant therapy for locally advanced rectal cancer.

MATERIALS AND METHODS

A systematic search of Pubmed, EMBASE and Cochrane databases for synonyms of 'rectal cancer', 'radiotherapy' and 'boost' was carried out. Studies were screened for radiotherapy prescription >54 Gy. Prespecified quality assessment was carried out for meta-analysis inclusion suitability. Pooled estimates of pCR, acute toxicity (grade ≥3) and R0 resection rates were determined with random-effects restricted maximum-likelihood estimation. Heterogeneity was assessed with Higgins I² and Cochran Q statistic. Subset analysis examined outcomes in modern inverse-planning studies. Meta-regression with permutation correction was carried out for each outcome against radiation dose, radiotherapy technique, boost technique, chemotherapy intensification and other patient- and treatment-related cofactors.

RESULTS

Forty-nine primary and three follow-up publications were included in the systematic review. Pooled estimates of pCR, toxicity and R0 resection across 37 eligible publications (n = 1817 patients) were 24.1% (95% confidence interval 21.2-27.4%), 11.2% (95% confidence interval 7.2-17.0%) and 90.7% (95% confidence interval 87.9-93.8%). Within inverse-planning studies (17 publications, n = 959 patients), these rates were 25.7% (95% confidence interval 21.0-31.1%), 9.8% (95% confidence interval 4.6-19.7%) and 95.3% (95% confidence interval 91.6-97.4%). Regression analysis did not identify any significant predictor of pCR (P > 0.05).

CONCLUSIONS

Radiotherapy dose escalation above 54 Gy is associated with high rates of pCR and does not seem to increase the risk of acute grade ≥3 toxicity events. pCR rates approaching 25% may be achievable utilising moderate escalation (54-60 Gy) with modern inverse-planning techniques; however, a clear dose-response relationship was not identified in regression analysis and additional evidence is awaited given the prevalence of heterogenous single-arm studies to date.

Efficacy of Dose-Escalated Chemoradiation on Complete Tumor Response in Patients with Locally Advanced Rectal Cancer (RECTAL-BOOST): A Phase 2 Randomized Controlled Trial

PURPOSE

Pathologic complete tumor response after chemoradiation in patients with locally advanced rectal cancer (LARC) is associated with a favorable prognosis and allows organ-sparing treatment strategies. In the RECTAL-BOOST trial, we aimed to investigate the effect of an external radiation boost to the tumor before chemoradiation on pathologic or sustained clinical complete tumor response in LARC.

METHODS AND MATERIALS

This multicenter, nonblinded, phase 2 randomized controlled trial followed the trials-within-cohorts design, which is a pragmatic trial design allowing cohort participants to be randomized for an experimental intervention. Patients in the intervention group are offered the intervention (and can either accept or refuse this), whereas patients in the control group are not notified about the randomization. Participants of a colorectal cancer cohort referred for chemoradiation of LARC to either of 2 radiation therapy centers were eligible. Patients were randomized to no boost or an external radiation boost (5 × 3 Gy) without concurrent chemotherapy, directly followed by standard pelvic chemoradiation (25 × 2 Gy with concurrent capecitabine). The primary outcome was pathologic complete response (ie, ypT0N0) in patients with planned surgery at 12 weeks, or, as surrogate for pathologic complete response, a 2-year sustained clinical complete response for patients treated with an organ preservation strategy. Analyses were intention to treat. The study was registered with ClinicalTrials.gov, number NCT01951521.

RESULTS

Between September 2014 and July 2018, 128 patients were randomized. Fifty-one of the 64 (79.7%) patients in the intervention group accepted and received a boost. Compared with the control group, fewer patients in the intervention group had a cT4 stage and a low rectal tumor (31.3% vs 17.2% and 56.3% vs 45.3%, respectively), and more patients had a cN2 stage (59.4% vs 70.3%, respectively). Rate of pathologic or sustained clinical complete tumor response was similar between the groups: 23 of 64 (35.9%; 95% confidence interval [CI], 24.3-48.9) in the intervention group versus 24 of 64 (37.5%; 95% CI, 25.7-50.5) in the control group (odds ratio [OR] = 0.94; 95% CI, 0.46-1.92). Near-complete or complete tumor regression was more common in the intervention group (34 of 49; 69.4%) than in the control group (24 of 53; 45.3%; (OR = 2.74, 95% CI 1.21-6.18). Grade ≥3 acute toxicity was comparable: 6 of 64 (9.4%) in the intervention group versus 5 of 64 (7.8%) in the control group (OR = 1.22; 95% CI, 0.35-4.22).

CONCLUSIONS

Dose escalation with an external radiation therapy boost to the tumor before neoadjuvant chemoradiation did not increase the pathologic or sustained clinical complete tumor response rate in LARC.

Prognostic Value of Serum NPY Hypermethylation in Neoadjuvant Chemoradiotherapy for Rectal Cancer: Secondary Analysis of a Randomized Trial

OBJECTIVES

Long-term prevention of metastatic disease remains a challenge in locally advanced rectal cancer, and robust pretreatment prognostic factors for metastatic progression are lacking. We hypothesized that detecting circulating tumor-specific DNA (ctDNA) based on hypermethylation of the neuropeptide Y gene (meth-ctDNA) could be a prognostic marker in the neoadjuvant setting; we examined this in a secondary, explorative analysis of a prospective trial.

MATERIALS AND METHODS

Serum samples were prospectively collected in a phase III trial for locally advanced rectal cancer. Positivity for and fractional abundance of meth-ctDNA in baseline samples were estimated. Overall survival (OS) and the rate of distant metastases were compared between meth-ctDNA positive and negative patients; other prognostic factors were controlled for in multivariate Cox regression. Importance of quantitative load was examined by considering the fractional abundance of meth-ctDNA relative to total circulating DNA.

RESULTS

Baseline serum samples were available for 146 patients. In total, 30 patients had presence of meth-ctDNA, with no correlation with cT (P=0.8) or cN (P=0.6) stages. Median follow-up was 10.6 years for OS and 5.1 years for freedom from distant metastases. Patients with meth-ctDNA had significantly worse 5-year OS (47% vs. 69%), even when controlling for other prognostic factors (hazard ratio=2.08; 95% confidence interval, 1.23-1.51). This seemed mainly driven by disparity in the rate of distant metastases (55% vs. 72% at 5 y, P=0.01); hazard ratio=2.20 (95% confidence interval, 1.19-4.07, P=0.01) in multivariate analysis. Increased quantitative load was highly significant for worse outcomes.

CONCLUSIONS

Meth-ctDNA could be a potential prognostic marker in the neoadjuvant setting and may, if validated, identify patients at increased risk of distant metastases.

A comparative analysis between radiation dose intensification and conventional fractionation in neoadjuvant locally advanced rectal cancer: a monocentric prospective observational study

PURPOSE

The potential role of neoadjuvant radiation dose intensification in locally advanced rectal cancer (LARC) is still largely debated. In the present study, a comparative analysis between radiation dose intensification and conventional fractionation was performed.

MATERIALS AND METHODS

In the current prospective observational study (protocol ID RT-03/2011), 56 patients diagnosed with LARC were enrolled between January 2013 and December 2016. More specifically, 25 patients underwent preoperative conventional radiation dose [i.e., 50.4 Gy in 28 fractions here defined as standard dose radiotherapy (SDR)-group 1], whereas 31 patients were candidate for radiation dose intensification (RDI) (i.e., 60 Gy in 30 fractions-group 2). The primary endpoint was the complete pathological response (pCR) rate. Secondary endpoints were postoperative complications and ChT-RT-related toxicity.

RESULTS

No statistical significance was observed in pCR rate (20.8% and 22.6% in SDR and RDI group, respectively, p = 0.342). Of contrast, the RDI group showed a significantly higher primary tumor downstaging in case of T3 tumor compared to SDR group (p = 0.049). Sphincter-preserving surgery was 84% and 93.5% in SDR and RDI groups, respectively (p = 0.25). All patients had R0 margins. No surgical-related death was recorded. No statistically significant difference was observed regarding surgical complications and incomplete mesorectal excision. Acute genitourinary toxicity was significantly higher in RDI group (p = 0.015).

CONCLUSIONS

The intensification of the neoadjuvant radiotherapy for LARC seems to produce a major pathological response in T3 tumors. The radiation dose intensification appears probably associated with a higher rate of genitourinary toxicity.

Role of radiotherapy in the treatment of rectal cancer in older patients

Striking a balance between cancer treatment and patient-centred care is becoming ever more important in older patients with rectal cancer as the population is ageing. The treatment decision made by the modern multidisciplinary colorectal team will recommend pre-operative chemo-radiotherapy followed by surgery for advance rectal cancer and surgery alone for early rectal cancer, as the "standard of care" is surgery. However, an alternative non-surgical treatment option should be consider for older patients with rectal cancer as the surgical harm can far outweigh the potential benefits. There is published evidence that mortality is higher with increasing age. An alternative treatment option to surgery when patients are not suitable or refusing surgery is to offer them external beam radiotherapy (EBRT) or chemo radiotherapy (EBCRT). A proportion of these patients can achieve a clinical complete response (cCR) which enable adoption of 'watch and wait' strategy to avoid surgery. However, a third of patients who achieved initial cCR can develop local regrowth within the first two years. This require salvage surgery which reduces their chance of organ preservation. Contact X-ray brachytherapy (CXB) or High Dose Rate Endo Brachy Therapy (HDREBT) boost following external beam radiotherapy can improve the initial cCR rate and reduce the risk of local regrowth. Those patients with persistent residual cancer or regrowth after brachytherapy boost following EBCRT or EBRT can have salvage surgery later without compromising their chance of cure. Therefore, patients should be fully aware of their treatment options and have 'a choice' when deciding and consenting their treatment.

Magnetic Resonance Guided Radiotherapy for Rectal Cancer: Expanding Opportunities for Non-Operative Management

Colorectal cancer is the third most common cancer in men and the second most common in women worldwide, and the incidence is increasing among younger patients. 30% of these malignancies arise in the rectum. Patients with rectal cancer have historically been managed with preoperative radiation, followed by radical surgery, and adjuvant chemotherapy, with permanent colostomies in up to 20% of patients. Beginning in the early 2000s, non-operative management (NOM) of rectal cancer emerged as a viable alternative to radical surgery in select patients. Efforts have been ongoing to optimize neoadjuvant therapy for rectal cancer, thereby increasing the number of patients potentially eligible to forgo radical surgery. Magnetic resonance guided radiotherapy (MRgRT) has recently emerged as a treatment modality capable of intensifying preoperative radiation therapy for rectal cancer patients. This technology may also predict which patients will achieve a complete response to preoperative therapy, thereby allowing for more appropriate selection of patients for NOM. The present work seeks to illustrate the potential role MRgRT could play in personalizing rectal cancer treatment thus expanding the role of NOM in rectal cancer.

MR-guided radiotherapy in rectal cancer: First clinical experience of an innovative technology

•This study represents one of the first reports of online MRgRT.•Integrated Low-field MR provides better anatomical visualization than CBCT or MVCT.•Better visualization of the target can help to reduce the margins from CTV to PTV.•MRgRT appears a feasible option in rectal cancer treatment offering potential benefits.•MRgRT represents a promising technology for rectal cancer management.

The 2017 Assisi Think Tank Meeting on rectal cancer: A positioning paper

BACKGROUND AND PURPOSES

To describe current practice in the management of rectal cancer, to identify uncertainties that usually arise in the multidisciplinary team (MDT)'s discussions ('grey zones') and propose next generation studies which may provide answers to them.

MATERIALS AND METHODS

A questionnaire on the areas of controversy in managing T2, T3 and T4 rectal cancer was drawn up and distributed to the Rectal-Assisi Think Tank Meeting (ATTM) Expert European Board. Less than 70% agreement on a treatment option was indicated as uncertainty and selected as a 'grey zone'. Topics with large disagreement were selected by the task force group for discussion at the Rectal-ATTM.

RESULTS

The controversial clinical issues that had been identified within cT2-cT3-cT4 needed further investigation. The discussions focused on the role of (1) neoadjuvant therapy and organ preservation on cT2-3a low-middle rectal cancer; (2) neoadjuvant therapy in cT3 low rectal cancer without high risk features; (3) total neoadjuvant therapy, radiotherapy boost and the best chemo-radiotherapy schedule in T4 tumors. A description of each area of investigation and trial proposals are reported.

CONCLUSION

The meeting successfully identified 'grey zones' and, in the light of new evidence, proposed clinical trials for treatment of early, intermediate and advanced stage rectal cancer.

Trends in combined radio-chemotherapy for locally advanced rectal cancer: a survey among radiation oncology centers of Sicily region on behalf of AIRO

AIM

To conduct a survey among Sicilian centers of radiation oncology belonging to Associazione Italiana di Radioterapia ed Oncologia Clinica (AIRO), to record the different methods of integration of radio-chemotherapy both in neoadjuvant and adjuvant settings, to evaluate surgical procedures in relation to the sphincter preservation and to report the different toxicity profiles of the treatment strategies.

METHODS

A questionnaire was sent at the end of 2017 to all the radiation oncology centers of Sicily region in order to collect the data from individual centers and the treatment characteristics retrospectively over the previous 5 years, from 2012 to 2016. The required data were collected from 13 centers out of 17 which, in relation to the single catchment areas, correspond to approximately 85% of the Sicilian population. The requested data concerned the type of integrated treatment (neoadjuvant vs adjuvant vs radical), combination with chemotherapy (induction, concomitant, adjuvant), type of surgical intervention (sphincter-saving vs abdomino-perineal resection), disease stage, schedule and radiotherapy technique adopted, as well as toxicity detected over the treatment period.

RESULTS

A total of 784 pts (M/F: 509/275) were treated between 2012 and 2016, with a median age of 67 years (range 25-92). The majority of patients was treated in the neoadjuvant phase (62% of the total) compared to the adjuvant phase (31%) and to those treated radically (7%). Twenty-five percent of patients did not receive combination chemotherapy mainly for cardiovascular problems. Chemotherapy used concomitantly to radiotherapy was single-agent capecitabine (73% of patients) or 5-fluorouracil (27%). The use of chemotherapy alone before concomitant treatment is more common for patients treated in the adjuvant phase (64% of this subgroup), while 14% of patients treated in the neoadjuvant phase received induction chemotherapy before the concomitant phase; in both cases of chemotherapy alone, the majority of patients (91%) received oxaliplatin-based protocols (FOLFOX/XELOX/CAPOX). Few patients (3%) received chemotherapy alone after the concomitant phase. Information on the surgical treatment received is available for 88% of the sample. Of these, 93% received a surgical treatment. The overall rate of sphincter-saving surgery (anterior resection) was 72%, but the contribution of neoadjuvant treatment allowed to reach a rate of 83% in this subgroup (against 65% found in the subgroup of patients treated in adjuvant phase). Traditional radiotherapy schedule (45-50 Gy in 25-28 fractions) was used in 90% of patients, of which an intensified treatment in neoadjuvant phase (45 Gy + boost of 9-10 Gy) was used in 11% of patients. A short-course regimen (25 Gy in 5 fraction) in neoadjuvant setting was opted rarely (7%). Three-dimensional conformal technique was preferred over intensity-modulated ones (73% vs 27%). Toxicity was mainly of grade I-II CTCAE (skin 23%, gastrointestinal 39%, genitourinary 14%) compared to grade III (gastrointestinal 4%, genitourinary and hematological < 1%). Interestingly, the toxicity rates were significantly higher in the adjuvant group compared to the neoadjuvant (GI: 58% vs 31%, GU: 21% vs 10%).

CONCLUSION

The present survey shows that in the Sicily region integrated therapies for rectal cancer have allowed a neoadjuvant approach in the majority of patients, thus resulting in a greater use of sphincter conservative surgery. The toxicity has also been reported to be significantly less in this treatment setting.

Optimal management of localized rectal cancer in older patients

In advising the optimal management for older patients, health care professionals try to balance the risks from frailty, vulnerability, and comorbidity against the patient's ultimate prognosis, potential functional outcomes and quality of life (QOL). At the same time it is important to involve the patient and incorporate their preferences. But how can we present and balance the potential downside of radical radiotherapy and risks of unsalvageable recurrence against the potential risks of postoperative morbidity and mortality associated with radical surgery? There are currently no nationally approved and evidence-based guidelines available to ensure consistency in discussions with older adults or frail and vulnerable patients. In this overview we hope to provide an insightful discussion of the relevant issues and options currently available.

Method for Automatic Selection of Parameters in Normal Tissue Complication Probability Modeling

PURPOSE

To present a fully automatic method to generate multiparameter normal tissue complication probability (NTCP) models and compare its results with those of a published model, using the same patient cohort.

METHODS AND MATERIALS

Data were analyzed from 345 rectal cancer patients treated with external radiation therapy to predict the risk of patients developing grade 1 or ≥2 cystitis. In total, 23 clinical factors were included in the analysis as candidate predictors of cystitis. Principal component analysis was used to decompose the bladder dose-volume histogram into 8 principal components, explaining more than 95% of the variance. The data set of clinical factors and principal components was divided into training (70%) and test (30%) data sets, with the training data set used by the algorithm to compute an NTCP model. The first step of the algorithm was to obtain a bootstrap sample, followed by multicollinearity reduction using the variance inflation factor and genetic algorithm optimization to determine an ordinal logistic regression model that minimizes the Bayesian information criterion. The process was repeated 100 times, and the model with the minimum Bayesian information criterion was recorded on each iteration. The most frequent model was selected as the final "automatically generated model" (AGM). The published model and AGM were fitted on the training data sets, and the risk of cystitis was calculated.

RESULTS

The 2 models had no significant differences in predictive performance, both for the training and test data sets (P value > .05) and found similar clinical and dosimetric factors as predictors. Both models exhibited good explanatory performance on the training data set (P values > .44), which was reduced on the test data sets (P values < .05).

CONCLUSIONS

The predictive value of the AGM is equivalent to that of the expert-derived published model. It demonstrates potential in saving time, tackling problems with a large number of parameters, and standardizing variable selection in NTCP modeling.

Session 3: Boosting primary and recurrent rectal cancer: how far can we push the radiotherapy envelope?

Neoadjuvant pelvic radiotherapy is widely used for patients with advanced rectal cancer. The trade-off between dose and response is well-established, yet little consensus remains on the precise methods of delivery and doses given in different scenarios. Professor Vuong reviews the evidence base and trial evidence on the escalation of radiotherapy dose and the methods of achieving this.

Session 4: Shaping radiotherapy for rectal cancer: should this be personalized?

Preoperative radiotherapy continues to be widely used in patients with operable rectal cancer. However, the indications and goals for such treatment are evolving. Professor Marijnen reviews the historic and current evidence base for the use of preoperative neoadjuvant radiotherapy and the future challenges in tailoring the therapy according to the patients' needs and tumour stage.

Neoadjuvant therapy and subsequent treatment in rectal cancer: balance between oncological and functional outcomes

Current practice of neoadjuvant therapy and total mesorectal excision (TME) in rectal cancer bears the weakness in systemic disease control and long-term functional outcomes. With increasing concerns of the balance between cure and quality of life, new strategies are developed to better oncological outcomes at least cost of function damage. Attractive options to adjust neoadjuvant modality include escalation of radiotherapy, intensification of chemotherapy, and chemoradiotherapy with consolidation or full-course chemotherapy. Subsequently, organ-preserving strategies have gained the popularity. Surgical or nonsurgical approaches that spare the rectum are used as possible alternatives for radical surgery, though high-quality TME remains the last resort to offer reliable local disease control. This review discusses new strategies of neoadjuvant therapy and subsequent management, with a specific focus on the balance between oncological and functional outcomes.

Decision-Making Strategy for Rectal Cancer Management Using Radiation Therapy for Elderly or Comorbid Patients

Rectal cancer predominantly affects patients older than 70 years, with peak incidence at age 80 to 85 years. However, the standard treatment paradigm for rectal cancer oftentimes cannot be feasibly applied to these patients owing to frailty or comorbid conditions. There are currently little information and no treatment guidelines to help direct therapy for patients who are elderly and/or have significant comorbidities, because most are not included or specifically studied in clinical trials. More recently various alternative treatment options have been brought to light that may potentially be utilized in this group of patients. This critical review examines the available literature on alternative therapies for rectal cancer and proposes a treatment algorithm to help guide clinicians in treatment decision making for elderly and comorbid patients.

Advances in organ preserving strategies in rectal cancer patients

Treatment of rectal cancer patients has been subjected to change over the past thirty years. Total mesorectal excision is considered the cornerstone of rectal cancer treatment, but is also associated with significant morbidity resulting in an impaired quality of life. The addition of neoadjuvant chemoradiotherapy to surgery has shown to improve survival and local control and may lead to a partial or even complete response (CR). This raises questions regarding the necessity for subsequent radical surgery. After careful patient selection local excision and wait-and-see approaches are explored, aiming to improve quality of life without compromising oncological outcome. A multimodality diagnostic approach for optimal staging is crucial in determining the appropriate neoadjuvant treatment regimen. Adequate endoscopic restaging of rectal tumours after multimodality treatment will aid in selecting patients who are eligible for an organ preserving approach. The role and accuracy of imaging in the detection of the primary tumour, residual rectal cancer or local recurrence seems vital. Alternative neoadjuvant regimens are currently explored to increase the rate of clinical CRs, which may support organ preserving approaches. This review aims to generate insight into the advances in diagnostics and treatment modalities in all stages of rectal cancer and will highlight future studies that may support further implementation of organ preservation treatment in rectal cancer.

Dosimetric Evaluation of a Flexible Dual Balloon-Constructed Applicator in Treating Anorectal Cancer

Background and Purpose:

Materials and Methods:

Results:

Conclusion:

Management of the Complete Clinical Response

Organ preservation is considered in the management of selected patients with rectal cancer. Complete clinical response observed after neoadjuvant chemoradiation for rectal cancer is one of these cases. Patients who present complete clinical response are candidates to the watch-and-wait approach, when radical surgery is not immediately performed and is offered only to patients in the event of a local relapse. These patients are included in a strict follow-up, and up of 70% of them will never be operated during the follow-up. This strategy is associated with similar oncological outcomes as patients operated on, and the advantage of avoiding the morbidity associated to the radical operation. In this article we will discuss in detail the best candidates for this approach, the protocol itself, and the long-term outcomes.

Adaptive radiation dose escalation in rectal adenocarcinoma: a review

Total mesorectal excision (TME) after neoadjuvant chemoradiotherapy (CRT) has offered superior control for patients with locally advanced rectal cancer, but can carry a quality of life cost. Fortunately, some patients achieve a complete response after CRT alone without the added morbidity caused by surgery. Efforts to increase fidelity of radiation treatment planning and delivery may allow for escalated doses of radiotherapy (RT) with limited off-target toxicity and elicit more pathological complete responses (pCR) to CRT thereby sparing more rectal cancer patients from surgery. In this review, methods of delivering escalated RT boost above 45-50.4 Gy are discussed including: 3D conformal, intensity-modulated radiotherapy (IMRT), and brachytherapy. Newly developed adaptive boost strategies and imaging modalities used in RT planning and response evaluation such as magnetic resonance imaging (MRI) and positron emission tomography (PET) are also discussed.

Endoluminal and Interstitial Brachytherapy for the Treatment of Gastrointestinal Malignancies: a Systematic Review

Radiation therapy is an integral component in the multimodality management of many gastrointestinal (GI) cancers at all stages of clinical presentation. With recent advances in technology and radiation delivery, external beam radiation therapy (EBRT) can be delivered with reduced toxicity. However, despite these advances, EBRT doses are still limited by the presence of radiosensitive serial structures near clinical targets in the GI tract. Relative to EBRT techniques, brachytherapy techniques have a lower integral dose and more rapid fall-off, allowing for high-dose delivery with little normal tissue exposure. Given the unique characteristics of brachytherapy, it is an attractive strategy to treat GI malignancies. This review addresses the application of both high-dose rate brachytherapy (HDRBT) and low-dose rate brachytherapy (LDRBT) to multiple GI malignancies for both definitive and palliative management.

Adjuvant Second-Dose Chemotherapy before Surgery for Patients with Locally Advanced Rectal Malignancy Is Not Beneficial: A Systematic Review and Meta-Analysis

BACKGROUND

Preoperative chemoradiotherapy is the standard treatment for patients with locally advanced rectal cancer, although tumor responses vary widely; some patients may achieve a pathologic complete response rate (pCR) after chemoradiotherapy. Controversy exists with regard to the efficacy of different preoperative combination chemotherapy regimens and neoadjuvant chemoradiotherapy, compared with chemoradiotherapy alone.

METHODS

PubMed, the Cochrane Library, and Embase databases were searched for comparative studies of patients with locally advanced rectal cancer that were published between January 1991 and January 2016. Efficacies of different preoperative combination chemotherapy regimens and neoadjuvant chemoradiotherapy (group A) were compared with chemoradiotherapy alone (group B) in a meta-analysis using Review Manager v5.2.

RESULTS

Three prospective randomized controlled trials and two prospective nonrandomized controlled trials comprising 444 cases were eligible for analysis. No significant difference was detected in the rate of pCR (50/223, 22.4% versus 35/223, 15.7%; relative risk, RR: 1.42 [95% confidence interval, CI: 0.97-2.09], p = 0.07) between the two groups. The rate of tumor regression was similar for both groups (122/203, 60.1% versus 111/203, 54.7%; RR: 1.11 [95% CI: 0.94-1.29], p = 0.22).

CONCLUSIONS

Adjuvant chemotherapy with preoperative chemoradiotherapy did not significantly improve the rate of pCR nor the rate of T and N downstaging.

Inflatable multichannel rectal applicator for adaptive image-guided endoluminal high-dose-rate rectal brachytherapy: design, dosimetric characteristics, and first clinical experiences

Purpose

To investigate the dosimetric results and first clinical experiences with a new designed balloon applicator with adjustable catheters for endoluminal brachytherapy for patients with locally advanced rectal cancer not undergoing surgery.

Material and methods

The applicator consists of an inflatable rectal balloon with six attached Foley catheters used as guidance for the inserted brachytherapy plastic needles. The construction of the applicator and the dosimetric profile in terms of representative dose points in 0, 2, 5, 10 mm ipsilaterally and in 0 mm contralaterally are described. The first clinical outcomes in three patients are reported.

Results

For all three patients, a reproducible dose gradient was achieved. The surface dose on the target side was 204 ± 19% of the normalized dose in 5 mm (100%) tissue depth, and 143 ± 8% in 2 mm and 64 ± 3% in 10 mm tissue depth, while the surface dose on the contra-lateral side was 20 ± 8%. After radiochemotherapy with 50 Gy external beam radiotherapy and concomitant administration of capecitabine, a HDR brachytherapy boost in 2-3 fractions of 7-10 Gy each was delivered. All patients achieved a clinical complete response 3 month after the treatment, and no major toxicity was observed.

Conclusion

The use of the applicator was clinically feasible, and resulted in a stable and reproducible dose distribution. First clinical results are promising.

High-Dose-Rate Brachytherapy in the Management of Operable Rectal Cancer: A Systematic Review

PURPOSE

To evaluate the role of high-dose-rate endorectal brachytherapy (HDREBT) in the preoperative and definitive management of operable rectal cancer in terms of clinical outcomes and toxicities using a systematic review.

METHODS AND MATERIALS

A review of published articles from January 1990 to December 2016 was conducted using the PubMed, Embase, and Scopus databases using the search terms "rectal" or "rectum" in combination with "brachytherapy," "high dose rate," "HDR," and "endorectal." Additional publications were identified by scanning references. Only studies published in English reporting clinical outcomes with ≥30 patients treated with HDREBT were included.

RESULTS

The search identified 1688 articles, of which 22 met our inclusion criteria. Twelve studies were included in this systematic review. Following preoperative HDREBT with chemoradiation therapy (CRT), the pathologic complete response (pCR) rate ranged between 18% and 31% (weighted mean rate, 22.2%); R0 resection rate, between 80% and 99% (weighted mean rate, 95.5%); and sphincter-preservation rate, between 29% and 54% (weighted mean rate, 46.4%). The weighted mean 2-year progression-free survival and overall survival (OS) rates were 68.1% and 81.5%, respectively. After preoperative HDREBT alone, the pCR rate ranged between 10.4% and 27% (weighted mean rate, 23.8%), the R0 rate was 96.5% (1 study), and the sphincter-preservation rate ranged between 53.8% and 75.8% (weighted mean rate, 59.4%). The weighted mean 5-year progression-free survival and OS rates were 66.6% and 70.8%, respectively. There was only 1 study of HDREBT for nonsurgical management of rectal cancer, which reported a 2-year OS rate of 100%.

CONCLUSIONS

Preoperative HDREBT either alone or in combination with CRT may result in a better pCR but may not necessarily translate into better survival, which is similar to outcomes seen following preoperative CRT alone. There were significant variations across studies in terms of patient selection, treatment approaches, and evaluation of clinical outcomes, suggesting the need for an international consensus on the dosimetric parameters and techniques of HDREBT, timing and methods of response assessment, definitions and assessment of toxicities, and optimal timing of surgery before further prospective studies. Future studies should include evaluation of the role of HDREBT in the nonsurgical curative treatment of screen-detected early cancers and organ preservation in lower rectal cancers.

Association between the expression of microRNAs and the response of patients with locally advanced rectal cancer to preoperative chemoradiotherapy

Preoperative chemoradiotherapy (CRT) followed by mesorectal excision is the standard treatment for patients with locally advanced rectal cancer (LARC). The balance between treatment efficacy and toxicity is a major issue in the clinical management of these patients. There is a requirement for the identification of predictive molecular biomarkers for the response of patients to CRT. The present study aimed to analyze the association between microRNA (miRNA/miR) expression and treatment efficacy in patients with LARC who were treated with preoperative CRT. From previous clinical trials, 55 patients for the test cohort and 130 patients for the validation cohort met the criteria for the present investigation. Through reverse transcription-quantitative polymerase chain reaction analysis, the expression of miR-21, −31, −125b, −145 and −630 in the diagnostic biopsies was analyzed. The primary endpoint of tumor regression was evaluated according to Mandard's Tumor Regression Grade (TRG) system. In the test cohort, a significant association was identified between low miRNA-145 expression and TRG1+2 (P=0.0003). Similarly, this association was identified in the validation cohort, although it did not reach statistical significance. Furthermore, a significant association between high miRNA-21 expression and TRG1+2 (P=0.035) was observed in the validation cohort. The remaining miRNAs analyzed were not associated with TRG. The results of the present study highlight the clinical importance of miRNAs in LARC and underline the necessity for validation studies in this setting.

Preoperative radiation dose escalation for rectal cancer using a concomitant boost strategy improves tumor downstaging without increasing toxicity: A matched-pair analysis

Purpose

Pathologic complete response to neoadjuvant chemoradiation therapy (CRT) is associated with improved outcomes for patients with locally advanced rectal cancer (LARC). Increased response rates have been reported with higher radiation doses, but these studies often lack long-term outcome and/or toxicity data. We conducted a case-control analysis of patients with LARC who underwent definitive CRT to determine the efficacy and safety of intensified treatment with a concomitant boost (CB) approach.

Methods and materials

From 1995 to 2003, a phase 2 protocol examined CRT with 5-fluorouracil and CB radiation therapy (52.5 Gy in 5 weeks) for patients with LARC. Seventy-six protocol patients were matched (case-control approach) for surgery type, tumor (T) stage, and clinical nodal (N) stage with patients who received standard dose (SD) CRT (5-fluorouracil, 45 Gy). A chart review was performed. McNemar's test and Kaplan-Meier analyses were used for statistical analysis.

Results

The SD and CB groups did not differ in tumor circumferential involvement and length, but the tumors of CB patients were closer to the anal verge (4.7 vs 5.7 cm; P = .02). Although tumor downstaging was higher in the CB cohort (76% vs 51%; P < .01), pathologic complete response rates did not differ (CB, 17.1% vs SD, 15.8%, P = 1.00). The incidence of grade ≥3 radiation-related toxicities was low and similar in both groups (CB, 10% vs SD, 3%, P = .22). Postoperative (anastomotic leak, wound complications/abscess, bleeding) and late (small bowel obstruction, stricture) complication rates did not differ between the groups (P > .05). The median follow-up was 11.9 years. The 5-year local control rates were higher for CB (100.0%) compared with SD (90.0%) patients (P = .01). CB patients had higher rates of 10-year progression-free survival (71.9% vs 57.6%, P < .01) and overall survival (71.6% vs 62.4%, P = .01) compared with SD patients.

Conclusions

CRT dose escalation for patients with LARC is safe and effective. The improved T-downstaging and local control observed in CB patients should encourage further dose escalation studies.

On a prolonged interval between rectal cancer (chemo)radiotherapy and surgery

Preoperative radiotherapy (RT) or chemoradiotherapy (CRT) is often required before rectal cancer surgery to obtain low local recurrence rates or, in locally advanced tumours, to radically remove the tumour. RT/CRT in tumours responding completely can allow an organ-preserving strategy. The time from the end of the RT/CRT to surgery or to the decision not to operate has been prolonged during recent years. After a brief review of the literature, the relevance of the time interval to surgery is discussed depending upon the indication for RT/CRT. In intermediate rectal cancers, where the aim is to decrease local recurrence rates without any need for down-sizing/-staging, short-course RT with immediate surgery is appropriate. In elderly patients at risk for surgical complications, surgery could be delayed 5-8 weeks. If CRT is used, surgery should be performed when the acute radiation reaction has subsided or after 5-6 weeks. In locally advanced tumours, where CRT is indicated, the optimal delay is 6-8 weeks. In patients not tolerating CRT, short-course RT with a 6-8-week delay is an alternative. If organ preservation is a goal, a first evaluation should preferably be carried out after about 6 weeks, with planned surgery for week 8 if the response is inadequate. In case the response is good, a new evaluation should be carried out after about 12 weeks, with a decision to start a 'watch-and-wait' programme or operate. Chemotherapy in the waiting period is an interesting option, and has been the subject of recent trials with promising results.

Radiation dose intensification in pre-operative chemo-radiotherapy for locally advanced rectal cancer

BACKGROUND

To assess the role of radiation dose intensification with simultaneous integrated boost guided by 18-FDG-PET/CT in pre-operative chemo-radiotherapy (ChT-RT) for locally advanced rectal cancer.

METHODS

A prospective study was approved by the Internal Review Board. Inclusion criteria were: age >18 years old, World Health Organization performance status of 0-1, locally advanced histologically proven adenocarcinoma of the rectum within 10 cm of the anal verge, signed specific informed consent. High-dose volumes were defined including the hyper-metabolic areas of 18-FDG-PET/CT of primary tumor and the corresponding mesorectum and/or pelvic nodes with at least a standardized uptake values (SUV) of 5. A dose of 60 Gy/30 fractions was delivered. A total dose of 54 Gy/30 fractions was delivered to prophylactic areas. Capecitabine was administered concomitantly with RT for a dose of 825 mg/mq twice daily for 5 days/every week.

RESULTS

Between September 2011 and July 2015 fortypatients were recruited. At the time of the analysis, median follow up was 20 months (range 5-51). The median interval from the end of ChT-RT to surgery was 9 weeks (range 8-12). Thirty-seven patients (92.5 %) were submitted to sphincter preservation. Tumor Regression Grade (Mandard scale) was recorded as follows: grade 1 in 7 (17.5 %), grade 2 in 17 (42.5 %), grade 3 in 15 (37.5 %) and grade 4 in 1 (2.5 %). Post-surgical circumferential resection margin was negative in all patients. A tumor downstaging was reported in 62.5 % (95 % CI: 0.78-0.47). A nodes downstaging was registered in 85 % (95 % CI: 0.55-0.25). 18-FDG-PET/CT was not able to predict pCR. No correlation was found between pre-treatment SUV-max values and pCR. A metabolic tumor volume >127 cc was related to ypT ≥2 (p 0.01). Patients with TRG >2 had higher tumor lesion glycolysis values (p 0.05).

CONCLUSION

Preliminary results did not confirm some advantages in terms of primary tumor downstaging/downsizing compared to conventional schedules reported in historical series. The role of 18-FDG-PET/CT in neoadjuvant rectal cancer management needs to be confirmed in further investigations. Long terms results are necessary.