Stereotactic Body Radiation Therapy Reirradiation for Locally Recurrent Rectal Cancer: Outcomes and Toxicity

Definitive carbon ion re-irradiation with pencil beam scanning in the treatment of unresectable locally recurrent rectal cancer

This study aimed to evaluate the oncological outcomes and safety of carbon ion re-irradiation with pencil beam scanning (PBS) delivery technique for previously irradiated and unresectable locally recurrent rectal cancer (LRRC). Between June 2017 and September 2021, 24 patients of unresectable LRRC with prior pelvic photon radiotherapy who underwent carbon ion re-irradiation at our institute were retrospectively analyzed. Carbon ion radiotherapy was delivered by raster scanning with a median relative biological effectiveness-weighted dose of 72 Gy in 20 fractions. Weekly CT reviews were carried out, and offline adaptive replanning was performed whenever required. The median follow-up duration was 23.8 months (range, 6.2-47.1 months). At the last follow-up, two patients had a local disease progression, and 11 patients developed distant metastases. The 1- and 2-year local control, progression-free survival and overall survival rates were 100 and 93.3%, 70.8 and 45.0% and 86.7 and 81.3%, respectively. There were no Grade 3 or higher acute toxicities observed. Three patients developed Grade 3 late toxicities, one each with gastrointestinal toxicity, skin reaction and pelvic infection. In conclusion, definitive carbon ion re-irradiation with PBS provided superior oncologic results with tolerable toxicities and may be served as a curative treatment strategy in unresectable LRRC.

Effectiveness of Robotic Stereotactic Radiotherapy in Patients Undergoing Re-irradiation: A Review

Stereotactic ablative radiotherapy (SABR) is a possible treatment option for patients who develop recurrence within or at the edge of a previously irradiated volume. Robotic stereotactic radiotherapy is the result of technological advances in robotic precision, real-time imaging, non-invasive, highly customizable treatment plan, and delivery with sub-millimeter accuracy. This article reviews the radiobiologic, technical, and clinical aspects of robotic-based SABR re-irradiation for various anatomical sites. An extensive literature search was performed to identify articles on the utilization of robotic stereotactic radiotherapy for patients undergoing re-irradiation. The reported prescription dose and fractionation data along with outcomes such as overall survival, local control rates, and toxicities were qualitatively reviewed. The findings consistently indicate that re-irradiation using robotic SABR provides encouraging survival rates with minimal toxicity in the clinical setting of various anatomical sites delivered using locally non-invasive means where other treatment options are scarce.

Systematic Review of Patient-Reported Outcome Measures in Locally Recurrent Rectal Cancer

BACKGROUND

The availability of high-quality patient-reported outcome (PRO) data is crucial to guiding shared decision-making in the context of locally recurrent rectal cancer (LRRC), where potential treatment benefits must be balanced against the impact of both the disease and treatment on PROs, such as quality of life. This review aimed to identify the patient-reported outcome measures (PROMs) currently being reported in LRRC and to appraise the methodological quality of studies using these measures.

METHODS

PubMed, Embase and CINAHL databases were searched, including studies published up until 14th September 2022. Studies in adults with LRRC reporting PROMS as a primary or secondary outcome measure were included. Data were extracted concerning the methodological quality of the reporting of PROMs using criteria informed by the CONSORT-PRO checklist and the psychometric properties of the PROMs identified using the COSMIN Risk of Bias checklist.

RESULTS

Thirty-five studies including 1914 patients with LRRC were identified. None of the studies included in the review met all eleven criteria for the quality of reporting of PROMs. Seventeen PROMs and two clinician-reported outcome measures were identified, none of which have been validated for use in patients with LRRC.

CONCLUSIONS

None of the PROMs which are currently being used to report PROs in LRRC have been validated for use in this cohort of patients. Future studies in this disease area should focus on utilising PROMs that have undergone a robust development process including patients with LRRC, to produce data which is high quality, accurate and relevant.

Treatment plan optimisation for reirradiation

BACKGROUND

The STRIDeR (Support Tool for Re-Irradiation Decisions guided by Radiobiology) project aims to create a clinically viable re-irradiation planning pathway within a commercial treatment planning system (TPS). Such a pathway should account for previously delivered dose, voxel-by-voxel, taking fractionation effects, tissue recovery and anatomical changes into account. This work presents the workflow and technical solutions in the STRIDeR pathway.

METHODS

The pathway was implemented in RayStation (version 9B DTK) to allow an original dose distribution to be used as background dose to guide optimisation of re-irradiation plans. Organ at risk (OAR) planning objectives in equivalent dose in 2 Gy fractions (EQD2) were applied cumulatively across the original and re-irradiation treatments, with optimisation of the re-irradiation plan performed voxel-by-voxel in EQD2. Different approaches to image registration were employed to account for anatomical change. Data from 21 patients who received pelvic Stereotactic Ablative Radiotherapy (SABR) re-irradiation were used to illustrate the use of the STRIDeR workflow. STRIDeR plans were compared to those produced using a standard manual method.

RESULTS

The STRIDeR pathway resulted in clinically acceptable plans in 20/21 cases. Compared to plans produced using the laborious manual method, less constraint relaxation was required or higher re-irradiation doses could be prescribed in 3/21.

CONCLUSION

The STRIDeR pathway used background dose to guide radiobiologically meaningful, anatomically-appropriate re-irradiation treatment planning within a commercial TPS. This provides a standardised and transparent approach, offering more informed re-irradiation and improved cumulative OAR dose evaluation.

Dose-Escalated Magnetic Resonance Image–Guided Abdominopelvic Reirradiation With Continuous Intrafraction Visualization, Soft Tissue Tracking, and Automatic Beam Gating

Purpose

Methods and Materials

Results

Conclusions

An international Delphi consensus for pelvic stereotactic ablative radiotherapy re-irradiation

INTRODUCTION

Stereotactic Ablative Radiotherapy (SABR) is increasingly used to treat metastatic oligorecurrence and locoregional recurrences but limited evidence/guidance exists in the setting of pelvic re-irradiation. An international Delphi study was performed to develop statements to guide practice regarding patient selection, pre-treatment investigations, treatment planning, delivery and cumulative organs at risk (OARs) constraints.

MATERIALS AND METHODS

Forty-one radiation oncologists were invited to participate in three online surveys. In Round 1, information and opinion was sought regarding participants' practice. Guidance statements were developed using this information and in Round 2 participants were asked to indicate their level of agreement with each statement. Consensus was defined as ≥75% agreement. In Round 3, any statements without consensus were re-presented unmodified, alongside a summary of comments from Round 2.

RESULTS

Twenty-three radiation oncologists participated in Round 1 and, of these, 21 (91%) and 22 (96%) completed Rounds 2 and 3 respectively. Twenty-nine of 44 statements (66%) achieved consensus in Round 2. The remaining 15 statements (34%) did not achieve further consensus in Round 3. Consensus was achieved for 10 of 17 statements (59%) regarding patient selection/pre-treatment investigations; 12 of 13 statements (92%) concerning treatment planning and delivery; and 7 of 14 statements (50%) relating to OARs. Lack of agreement remained regarding the minimum time interval between irradiation courses, the number/size of pelvic lesions that can be treated and the most appropriate cumulative OAR constraints.

CONCLUSIONS

This study has established consensus, where possible, in areas of patient selection, pre-treatment investigations, treatment planning and delivery for pelvic SABR re-irradiation for metastatic oligorecurrence and locoregional recurrences. Further research into this technique is required, especially regarding aspects of practice where consensus was not achieved.

A multicentre retrospective review of SABR reirradiation in rectal cancer recurrence

BACKGROUND AND PURPOSE

Locally recurrent rectal cancer (LRRC) is associated with considerable morbidity, poor quality of life and an overall survival of 9 months. The non-operative treatment of LRRC is an understudied area, there is no consensus on management in this setting. We aim to perform a retrospective, multicentre analysis of patients treated with SABR reirradiation.

MATERIALS AND METHODS

All patients were identified who received SABR re-irradiation for LRRC, at 3 UK centres, between August 2015 and September 2020. Eligible patients had pelvic recurrence and were either not suitable/opted not for surgery, or margin positive after exenturative surgery. Patients were treated with 30 Gy in 5 fractions and followed up with clinical review and CT scan at 3, 6, 12, 18 and 24 months.

RESULTS

69 patients with 81 lesions were identified and median follow up was 28 months. Median progression free survival (PFS) and overall survival (OS) were 12.1 months (10.4, 17.7) and 38.7 months (28.9,-) respectively. 2-year OS was 0.77 (0.66, 0.89). 58.3% of deaths were as a result of consequences of local relapse. 42.6% of patients had local relapse at death or last follow up.

CONCLUSION

Our outcomes are encouraging for a population who had R1 resections, refused or were refused surgery; as they are similar to those in surgical series. Prospective data including details of survival, local relapse and QOL; with an optimised SABR technique, is required to establish SABR as an alternative to surgery.

A phase III randomized trial evaluating chemotherapy followed by pelvic reirradiation versus chemotherapy alone as preoperative treatment for locally recurrent rectal cancer - GRECCAR 15 trial protocol

AIM

Treatment strategies in locally recurrent rectal cancer (LRRC) are complex and need to be balanced against previous treatments received for the primary rectal cancer. Radiotherapy is an important component of treatment in LRRC. However, there is little high-quality evidence on the role of reirradiation in this cohort. Therefore, the aim of this trial is to assess the efficacy of neoadjuvant chemotherapy followed by pelvic reirradiation versus neoadjuvant chemotherapy alone on the rate of curative surgery (R0) in previously irradiated patients with LRRC.

METHOD

GRECCAR 15 is a prospective, multicentre, open-label, outcome assessor-blinded, superiority randomized controlled phase III clinical trial comparing neoadjuvant chemotherapy followed by pelvic reirradiation versus neoadjuvant chemotherapy alone in patients with LRRC previously irradiated for the primary cancer. Adult patients (>18 years old) with a histologically proven resectable LRRC, who have previously received pelvic radiotherapy for their primary rectal cancer at a dose of 25-50.4 Gy, and an Eastern Cooperative Oncology Group performance status of <2 will be eligible to participate. The pelvic reirradiation will consist of conformational intensity-modulated external irradiation, delivering a dose of 30.6 Gy with concomitant chemotherapy using capecitabine. The primary outcome of this trial is the R0 resection rate. Overall, GRECCAR 15 aims to recruit 186 patients to detect an absolute difference of 20% in the R0 resection rate with 80% power and 5% two-sided significance level.

CONCLUSION

The GRECCAR 15 trial is the first, definitive, phase III trial to investigate reirradiation in LRRC. The results of this trial will inform definitively the neoadjuvant treatment strategy in previously irradiated patients and assess whether there is any associated benefit of reirradiation in combination with induction chemotherapy in improving R0 resection rates.

Ultra hypofractionated extended nodal irradiation using volumetric modulated arc therapy for oligorecurrent pelvic nodal prostate cancer

Prostate cancer (PCa) may recur after primary treatment but no standard of care exists for patients with pelvic nodal relapse. Based on obervational data, Extended Nodal Irradiation (ENI) might be associated with fewer treatment failures than Stereotactic Ablative Radiotherapy (SABR) to the involved node(s) alone. Ultra hypofractionated ENI is yet to be evaluated in this setting, but it could provide a therapeutic advantage if PCa has a low α/β ratio in addition to patient convenience/resource benefits. This volumetric modulated arc therapy (VMAT) planning study developed a class solution for 5-fraction Extended Nodal Irradiation (ENI) plus a simultaneous integrated boost (SIB) to involved node(s). Ten patients with oligorecurrent nodal disease after radical prostatectomy/post-operative prostate bed radiotherapy were selected. Three plans were produced for each dataset to deliver 25 Gy in 5 fractions ENI plus SIBs of 40, 35 and 30 Gy. The biologically effective dose (BED) formula was used to determine the remaining dose in 5 fractions that could be delivered to re-irradiated segments of organs at risk (OARs). Tumour control probability (TCP) and normal tissue complication probability (NTCP) were calculated using the LQ-Poisson Marsden and Lyman-Kutcher-Burman models respectively. Six patients had an OAR positioned within planning target volume node (PTVn), which resulted in reduced target coverage to PTV node in six, five and four instances for 40, 35 and 30 Gy SIB plans respectively. In these instances, only 30 Gy SIB plans had a median PTV coverage >90% (inter-quartile range 90-95). No OAR constraint was exceeded for 30 Gy SIB plans, including where segments of OARs were re-irradiated. Gross tumour volume node (GTVn) median TCP was 95.7% (94.4-96), 90.7% (87.1-91.2) and 78.6% (75.8-81.1) for 40, 35 and 30 Gy SIB plans respectively, where an α/β ratio of 1.5 was assumed. SacralPlex median NTCP was 43.2% (0.7-61.2), 12.1% (0.6-29.7) and 2.5% (0.5-5.1) for 40, 35 and 30 Gy SIB plans respectively. NTCP for Bowel_Small was <0.3% and zero for other OARs for all three plan types. Ultra hypofractionated ENI planning for pelvic nodal relapsed PCa appears feasible with encouraging estimates of nodal TCP and low estimates of NTCP, especially where a low α/β ratio is assumed and a 30 Gy SIB is delivered. This solution should be further evaluated within a clinical trial and compared against SABR to involved node(s) alone.