ESTRO/ACROP IORT recommendations for intraoperative radiation therapy in locally recurrent rectal cancer

In vivodosimetry in cancer patients undergoing intraoperative radiation therapy

In vivodosimetry (IVD) is an important tool in external beam radiotherapy (EBRT) to detect major errors by assessing differences between expected and delivered dose and to record the received dose by individual patients. Also, in intraoperative radiation therapy (IORT), IVD is highly relevant to register the delivered dose. This is especially relevant in low-risk breast cancer patients since a high dose of IORT is delivered in a single fraction. In contrast to EBRT, online treatment planning based on intraoperative imaging is only under development for IORT. Up to date, two commercial treatment planning systems proposed intraoperative ultrasound or in-room cone-beam CT for real-time IORT planning. This makes IVD even more important because of the possibility for real-time treatment adaptation. Here, we summarize recent developments and applications of IVD methods for IORT in clinical practice, highlighting important contributions and identifying specific challenges such as a treatment planning system for IORT. HDR brachytherapy as a delivery technique was not considered. We add IVD for ultrahigh dose rate (FLASH) radiotherapy that promises to improve the treatment efficacy, when compared to conventional radiotherapy by limiting the rate of toxicity while maintaining similar tumour control probabilities. To date, FLASH IORT is not yet in clinical use.

Intra-operative Radiation Therapy for Colorectal or Anal Cancer at Risk for Margin-Positive Resection: Initial Results of a Single-Institution Registry

PURPOSE

Pelvic recurrence of rectal or anal cancers is associated with considerable morbidity and mortality. We report our initial experience with an aggressive intra-operative radiotherapy (IORT) program.

METHODS

Patients with locally advanced or recurrent rectal or anal cancers considered to have a high likelihood of R1 or R2 resection after multi-disciplinary review underwent surgical excision and IORT using a high-dose-rate afterloader (Ir-192) and HAM applicator. Endpoints included local or distant recurrence, and acute and late toxicity graded using the American College of Surgeons (ACS) NSQIP and the LENT-SOMA scale.

RESULTS

Twenty-one patients, largely with prior history of both pelvic external beam radiotherapy (EBRT, median 50.4 Gy) and surgical resection, underwent excision with IORT (median dose 12.5 Gy, range 10-15). Median follow-up was 20 months. Twelve (57%) patients had failure at the IORT site. Freedom from failure (FFF) within the IORT field was associated with resection status (FFF at 1 year 75% for R0 vs 15% for R1/2, p = 0.0065) but not re-irradiation EBRT or IORT dose (p > 0.05). Twelve, 5, and 13 patients experienced local, regional, and distant failure, respectively; 3 (14%) patients were disease-free at last follow-up. The most frequent acute toxicity was sepsis/abscess (24%). One patient (5%) required a ureteral stent; no patients developed neuropathy attributable to IORT.

CONCLUSIONS

In patients treated with excision and IORT for locally recurrent cancer, R0 resection is a critical determinant of local control. For patients with R1/2 resection, poor disease-free outcomes warrant consideration of a different treatment strategy.

Clinical feasibility of combining intraoperative electron radiation therapy with minimally invasive surgery: a potential for electron-FLASH clinical development

BACKGROUND

Local cancer therapy by combining real-time surgical exploration and resection with delivery of a single dose of high-energy electron irradiation entails a very precise and effective local therapeutic approach. Integrating the benefits from minimally invasive surgical techniques with the very precise delivery of intraoperative electron irradiation results in an efficient combined modality therapy.

METHODS

Patients with locally advanced disease, who are candidates for laparoscopic and/or thoracoscopic surgery, received an integrated multimodal management. Preoperative treatment included induction chemotherapy and/or chemoradiation, followed by laparoscopic surgery and intraoperative electron radiation therapy.

RESULTS

In a period of 5 consecutive years, 125 rectal cancer patients were treated, of which 35% underwent a laparoscopic approach. We found no differences in cancer outcomes and tolerance between the open and laparoscopic groups. Two esophageal cancer patients were treated with IOeRT during thoracoscopic resection, with the resection specimens showing intense downstaging effects. Two oligo-recurrent prostatic cancer patients (isolated nodal progression) had a robotic-assisted surgical resection and post-lymphadenectomy electron boost on the vascular and lateral pelvic wall.

CONCLUSIONS

Minimally invasive and robotic-assisted surgery is feasible to combine with intraoperative electron radiation therapy and offers a new model explored with electron-FLASH beams.

Practice-oriented solutions integrating intraoperative electron irradiation and personalized proton therapy for recurrent or unresectable cancers: Proof of concept and potential for dual FLASH effect

Background

Oligo-recurrent disease has a consolidated evidence of long-term surviving patients due to the use of intense local cancer therapy. The latter combines real-time surgical exploration/resection with high-energy electron beam single dose of irradiation. This results in a very precise radiation dose deposit, which is an essential element of contemporary multidisciplinary individualized oncology.

Methods

Patient candidates to proton therapy were evaluated in Multidisciplinary Tumor Board to consider improved treatment options based on the institutional resources and expertise. Proton therapy was delivered by a synchrotron-based pencil beam scanning technology with energy levels from 70.2 to 228.7 MeV, whereas intraoperative electrons were generated in a miniaturized linear accelerator with dose rates ranging from 22 to 36 Gy/min (at Dmax) and energies from 6 to 12 MeV.

Results

In a period of 24 months, 327 patients were treated with proton therapy: 218 were adults, 97 had recurrent cancer, and 54 required re-irradiation. The specific radiation modalities selected in five cases included an integral strategy to optimize the local disease management by the combination of surgery, intraoperative electron boost, and external pencil beam proton therapy as components of the radiotherapy management. Recurrent cancer was present in four cases (cervix, sarcoma, melanoma, and rectum), and one patient had a primary unresectable locally advanced pancreatic adenocarcinoma. In re-irradiated patients (cervix and rectum), a tentative radical total dose was achieved by integrating beams of electrons (ranging from 10- to 20-Gy single dose) and protons (30 to 54-Gy Relative Biological Effectiveness (RBE), in 10-25 fractions).

Conclusions

Individual case solution strategies combining intraoperative electron radiation therapy and proton therapy for patients with oligo-recurrent or unresectable localized cancer are feasible. The potential of this combination can be clinically explored with electron and proton FLASH beams.

Intra-Operative Electron Radiation Therapy: An Update of the Evidence Collected in 40 Years to Search for Models for Electron-FLASH Studies

Simple Summary

Four decades ago, intraoperative electron radiation therapy (IOeRT) was developed to improve precision in local cancer treatment by combining real-time surgical exploration and resection with high-energy electron irradiation. The technology of ultra-high dose rate electron and other radiation beams known as FLASH irradiation sharply increases its interests, as data from preclinical experiments have proven a marked favorable effect on the therapeutic index: similar cancer control with a clearly improved tolerance of many normal tissues to high doses of irradiation. The knowledge and tools regarding technology, physics, biology, and preclinical results in heterogeneous cancers opens great opportunities towards the path of developing the first clinical applications of the emerging FLASH technology via clinical trials based on state-of-the-art medical practice with IOeRT.

Abstract

Introduction: The clinical practice and outcome results of intraoperative electron radiation therapy (IOeRT) in cancer patients have been extensively reported over 4 decades. Electron beams can be delivered in the promising FLASH dose rate. Methods and Materials: Several cancer models were approached by two alternative radiobiological strategies to optimize local cancer control: boost versus exclusive IOeRT. Clinical outcomes are revisited via a bibliometric search performed for the elaboration of ESTRO/ACROP IORT guidelines. Results: In the period 1982 to 2020, a total of 19,148 patients were registered in 116 publications concerning soft tissue sarcomas (9% of patients), unresected and borderline-resected pancreatic cancer (22%), locally recurrent and locally advanced rectal cancer (22%), and breast cancer (45%). Clinical outcomes following IOeRT doses in the range of 10 to 25 Gy (with or without external beam fractionated radiation therapy) show a wide range of local control from 40 to 100% depending upon cancer site, histology, stage, and treatment intensity. Constraints for normal tissue tolerance are important to maintain tumor control combined with acceptable levels of side effects. Conclusions: IOeRT represents an evidence-based approach for several tumor types. A specific risk analysis for local recurrences supports the identification of cancer models that are candidates for FLASH studies.

Reporting quality of practice guidelines on colorectal cancer: evaluation using the RIGHT reporting checklist

Background

Clinical practice guidelines are an essential tool for translating evidence into practice. Reporting Items for Practice Guidelines in Healthcare (RIGHT) checklist assists to guide the reporting in guidelines. We used RIGHT to assess the reporting completeness and quality of guidelines on colorectal cancer (CRC).

Methods

We searched the electronic databases Medline (via PubMed), Chinese National Knowledge Infrastructure (CNKI), Wanfang and Chinese Biomedical Literature (CBM) from January 1st, 2018 to December 1st, 2020 for guidelines on CRC. Websites of guideline development organizations were also searched. Two investigators assessed the reporting quality of the included guidelines, and calculated the numbers of guidelines that were compliant with each RIGHT checklist item and the mean proportions of reported items for each of the seven RIGHT checklist domains.

Results

Twenty-seven colorectal guidelines were included. The proportions of reported items in each RIGHT domain were 71.0% for Basic information, 66.2% for Background, 45.9% for Evidence, 68.8% for Recommendations, 24.1% for Review and quality assurance, 33.3% for Funding and declaration and management of interests, and 40.7% for Other information.

Conclusions

The reporting quality of colorectal guidelines was moderate. A systematic use of the RIGHT checklist during the development process could improve the reporting quality of guidelines in the future.

The role of intraoperative radiotherapy in advanced rectal cancer: a meta-analysis

AIM

Patients with locally advanced and locally recurrent rectal cancer (LARC/LRRC) experience higher rates of local recurrence (LR) and poorer overall survival than patients with primary rectal cancer restricted to the mesorectum despite improved neoadjuvant treatment regimens and radical surgical procedures. Intraoperative radiotherapy (IORT) has been suggested as an adjunctive tool in the surgical management of these challenging cases. However, clear evidence regarding the oncological benefit of IORT is sparse. The aim of this review was to update this evidence in the era of standardized neoadjuvant radiotherapy administration.

METHOD

A systematic review of patients who received IORT as part of multimodal treatment for advanced rectal cancer from 2000 to 2020 and an analysis of IORT and surgery/external beam radiotherapy (EBRT) groups was performed. The primary endpoint was the rate of LR between the two groups.

RESULTS

Seven papers met the predefined criteria. LR was reduced by the addition of IORT when compared with the surgery/EBRT alone group (14.7% vs. 21.4%; OR 0.55, 95% CI 0.27-1.14; p = 0.11). There was no increase in reported genitourinary morbidity, wound issues, pelvic collections or anastomotic leak in those patients who received IORT. Notably, there was no survival difference between the two groups.

CONCLUSION

The addition of IORT to current treatment strategies in the management of patients with LARC/LRRC is associated with a lower rate of locoregional recurrence without increased morbidity. However, this marks a highly selective group of patients, with heterogeneity regarding indications, prior neoadjuvant treatments and/or IORT dosing.

Surgical treatment of locally recurrent rectal cancer: a narrative review

Objective

To summarize the recent literature on surgical treatment of locally recurrent rectal cancer (LRRC).

Background

LRRC is a heterogeneous disease that requires a multidisciplinary treatment approach. The treatment and prognosis depend on the site and type of recurrence. Radical resection remains the primary method for achieving long-term survival and improving symptom control. Preoperative chemoradiotherapy can reduce tumor volume and improve the R0 resection rate. Surgeons must clearly understand pelvic anatomy, develop a detailed preoperative plan, adopt a multidisciplinary approach for the surgical resection of the tumor as well as any invaded soft tissues, vessels, and bones, and ensure proper reconstruction. However, extended radical surgery often leads to a higher risk of postoperative complications and a low quality of life.

Methods

We searched English-language articles with keywords “locally recurrent rectal cancer”, “surgery” and “multidisciplinary team” in PubMed published between January 2000 to October 2020.

Conclusions

LRRC is a complex problem. Long-term survival is not impossible following multidisciplinary treatment in appropriately selected LRRC patients. The management of LRRC relies on a specialist team that determines the biological behavior of the tumor and evaluates treatment options through multidisciplinary discussions, thereby balancing the surgical costs and benefits, alleviating postoperative complications, and improving patients’ quality of life.

Intraoperative Electron Beam Radiation Therapy (IOERT) Versus High-Dose-Rate Intraoperative Brachytherapy (HDR-IORT) in Patients With an R1 Resection for Locally Advanced or Locally Recurrent Rectal Cancer

PURPOSE

Intraoperative radiation therapy (IORT), delivered by intraoperative electron beam radiation therapy (IOERT) or high-dose-rate intraoperative brachytherapy (HDR-IORT), may reduce the local recurrence rate in patients with locally advanced and locally recurrent rectal cancer (LARC and LRRC, respectively). The aim of this study was to compare the oncological outcomes between both IORT modalities in patients with LARC or LRRC who underwent a microscopic irradical (R1) resection.

METHODS

All consecutive patients who received IORT because of an R1 resection of LARC or LRRC between 2000 and 2016 in two tertiary referral centers were included. In LARC, a resection margin of ≤2 mm was considered R1. A resection margin of 0 mm was considered R1 in LRRC.

RESULTS

In total, 215 patients with LARC were included, of whom 151 (70%) received IOERT and 64 (30%) received HDR-IORT; in addition, 158 patients with LRRC were included, of whom 112 (71%) received IOERT and 46 (29%) received HDR-IORT. After multivariable analyses, the overall survival was not significantly different between the two IORT modalities. The local recurrence-free survival was significantly longer in patients treated with HDR-IORT, both in LARC (hazard ratio [HR], 0.496; 95% CI, 0.253-0.973; P = .041) and LRRC (HR, 0.567; 95% CI, 0.349-0.920; P = .021). In patients with LARC, major postoperative complications were similar for both IORT modalities (IOERT, 30%; HDR-IORT, 27%), whereas in patients with LRRC, the incidence of major postoperative complications was higher after HDR-IORT (IOERT, 26%; HDR-IORT, 46%).

CONCLUSIONS

This study showed a significantly better local recurrence-free survival in favor of HDR-IORT in patients with an R1 resection for LARC or LRRC. Optimization of the IOERT technique seems warranted.