European clinical practice guidelines for the definition, diagnosis, and treatment of oligometastatic esophagogastric cancer (OMEC-4)

INTRODUCTION

The OligoMetastatic Esophagogastric Cancer (OMEC) project aims to provide clinical practice guidelines for the definition, diagnosis, and treatment of esophagogastric oligometastatic disease (OMD).

METHODS

Guidelines were developed according to AGREE II and GRADE principles. Guidelines were based on a systematic review (OMEC-1), clinical case discussions (OMEC-2), and a Delphi consensus study (OMEC-3) by 49 European expert centers for esophagogastric cancer. OMEC identified patients for whom the term OMD is considered or could be considered. Disease-free interval (DFI) was defined as the time between primary tumor treatment and detection of OMD.

RESULTS

Moderate to high quality of evidence was found (i.e. 1 randomized and 4 non-randomized phase II trials) resulting in moderate recommendations. OMD is considered in esophagogastric cancer patients with 1 organ with ≤ 3 metastases or 1 involved extra-regional lymph node station. In addition, OMD continues to be considered in patients with OMD without progression in number of metastases after systemic therapy. 18F-FDG PET/CT imaging is recommended for baseline staging and for restaging after systemic therapy when local treatment is considered. For patients with synchronous OMD or metachronous OMD and a DFI ≤ 2 years, recommended treatment consists of systemic therapy followed by restaging to assess suitability for local treatment. For patients with metachronous OMD and DFI > 2 years, upfront local treatment is additionally recommended.

DISCUSSION

These multidisciplinary European clinical practice guidelines for the uniform definition, diagnosis and treatment of esophagogastric OMD can be used to standardize inclusion criteria in future clinical trials and to reduce variation in treatment.

TRIP12 governs DNA Polymerase β involvement in DNA damage response and repair

The multitude of DNA lesion types, and the nuclear dynamic context in which they occur, present a challenge for genome integrity maintenance as this requires the engagement of different DNA repair pathways. Specific 'repair controllers' that facilitate DNA repair pathway crosstalk between double strand break (DSB) repair and base excision repair (BER), and regulate BER protein trafficking at lesion sites, have yet to be identified. We find that DNA polymerase β (Polβ), crucial for BER, is ubiquitylated in a BER complex-dependent manner by TRIP12, an E3 ligase that partners with UBR5 and restrains DSB repair signaling. Here we find that, TRIP12, but not UBR5, controls cellular levels and chromatin loading of Polβ. Required for Polβ foci formation, TRIP12 regulates Polβ involvement after DNA damage. Notably, excessive TRIP12-mediated shuttling of Polβ affects DSB formation and radiation sensitivity, underscoring its precedence for BER. We conclude that the herein discovered trafficking function at the nexus of DNA repair signaling pathways, towards Polβ-directed BER, optimizes DNA repair pathway choice at complex lesion sites.

The impact of sex on treatment and outcome in relation to histological subtype in patients with resectable gastric cancer: Results from the randomized CRITICS trial

BACKGROUND AND OBJECTIVE

This study aims to investigate the impact of sex on outcome measures stratified by histological subtype in patients with resectable gastric cancer (GC).

METHODS

A post-hoc analysis of the CRITICS-trial, in which patients with resectable GC were treated with perioperative therapy, was performed. Histopathological characteristics and survival were evaluated for males and females stratified for histological subtype (intestinal/diffuse). Additionally, therapy-related toxicity and compliance were compared.

RESULTS

Data from 781 patients (523 males) were available for analyses. Female sex was associated with a distal tumor localization in intestinal (p = 0.014) and diffuse tumors (p < 0.001), and younger age in diffuse GC (p = 0.035). In diffuse GC, tumor-positive resection margins were also more common in females than males (21% vs. 10%; p = 0.020), specifically at the duodenal margin. During preoperative chemotherapy, severe toxicity occurred in 327 (63%) males and 184 (71%) females (p = 0.015). Notwithstanding this, relative dose intensities were not significantly different between sexes.

CONCLUSIONS

Positive distal margin rates were higher in females with diffuse GC, predominantly at the duodenal site. Females also experience more toxicity, but this neither impacts dose intensities nor surgical resection rates. Clinicians should be aware of these different surgical outcomes when treating males and females with GC.

Effect of preoperative chemotherapy on the histopathological classification of gastric cancer

BACKGROUND

In the era of individualized gastric cancer (GC) treatment, accurate determination of histological subtype becomes increasingly relevant. As yet, it is unclear whether preoperative chemotherapy may affect the histological subtype. The aim of this study was to assess concordance in histological subtype between pretreatment biopsies and surgical resection specimens before and after the introduction of perioperative treatment.

METHODS

Histological subtype was centrally determined in paired GC biopsies and surgical resection specimens of patients treated with either surgery alone (SA) in the Dutch D1/D2 study or with preoperative chemotherapy (CT) in the CRITICS trial. The histological subtype as determined in the resection specimen was considered the gold standard. Concordance rates and sensitivity and specificity of intestinal, diffuse, mixed, and "other" subtypes of GC were analyzed.

RESULTS

In total, 105 and 515 pairs of GC biopsies and resection specimens of patients treated in the SA and CT cohorts, respectively, were included. Overall concordance in the histological subtype was 72% in the SA and 74% in the CT cohort and substantially higher in the diffuse subtype (83% and 86%) compared to the intestinal (70% and 74%), mixed (21% and 33%) and "other" subtypes (54% and 54%). In the SA cohort, sensitivities and specificities were 0.88 and 0.71 in the intestinal, 0.67 and 0.93 in the diffuse, 0.20 and 0.98 in the mixed, and 0.50 and 0.93 in the "other" subtypes, respectively.

CONCLUSION

Our results suggest that accurate determination of histological subtype on gastric cancer biopsies is suboptimal but that the impact of preoperative chemotherapy on histological subtype is negligible.

Phase I feasibility study of Olaparib in combination with loco-regional radiotherapy in head and neck squamous cell carcinoma

Purpose

PARP-inhibitors have potent radiosensitizing properties in pre-clinical models. To identify the maximum tolerated dose (MTD) of the PARP-inhibitor Olaparib in combination with radiotherapy in patients with head and neck cancer, a single institutional phase-I dose escalation trial was initiated.

Patients and methods

The starting dose of Olaparib was 25 mg BID, combined with radiotherapy (70 Gy in 35 fractions). The MTD was defined as the highest dose-level at which not more than 20 % of patients experience dose-limiting toxicities (DLT) or as the highest reached dose in the absence of DLT's.

Results

One week Olaparib-only treatment (25 mg QD) was administered to all patients prior to the start of radiotherapy. In dose-level I, Olaparib (25 mg BID) was combined with accelerated radiotherapy (70 Gy in 6 weeks). Because of DLT's in 3 of the 4 treated patients (acute tracheotomy 5 and 7 months and osteoradionecrosis 7 months after treatment), the Olaparib dose was de-escalated to 25 mg QD, and combined with conventional radiotherapy (70 Gy in 7 weeks) (dose-level II). There were no DLT's observed in 5 patients treated within dose-level II. After a median follow-up of 60 months, the 4-year LRC and OS rates were 77.8 % and 88.9 %, respectively.

Conclusion

Olaparib 25 mg QD combined with conventionally fractionated radiotherapy was well tolerated and identified as the MTD while severe DLT's were observed when Olaparib 25 mg BID was combined with accelerated radiation. This combination might be further explored in future Olaparib dose escalation studies in patients with locally-advanced HNSCC unfit for cisplatin-based chemoradiotherapy.

Nationwide evaluation of pancreatic cancer networks ten years after the centralization of pancreatic surgery

BACKGROUND

Due to centralization of pancreatic surgery, patients with pancreatic cancer are treated in pancreatic cancer networks, composed of referring hospitals (Spokes) and an expert center (Hub). This study aimed to investigate I) how pancreatic cancer networks are organized and II) evaluated by involved clinicians.

METHODS

Two online surveys were sent out between January-May 2022. Part I was sent out to the surgical network directors of all hospitals of the Dutch Pancreatic Cancer Group (DPCG). Part II was sent out to all involved clinicians in the Hubs-and-Spokes networks.

RESULTS

There was a large variety between the 15 networks concerning number of affiliated Spokes (1-7), annual pancreatoduodenectomies (20-129), and use of a service level agreement (SLA) (40%). More Spoke clinicians considered the Spoke the best location for diagnostic workup (74% vs 36%, P < 0.001). Only 30% of Spoke clinicians attended the Hubs multidisciplinary team meeting frequently. More Hub clinicians thought that exchange of patient information should be improved (37% vs 51%, P = 0.005).

CONCLUSION

A large variety in Dutch pancreatic cancer networks was observed concerning number of affiliated Spokes, use of SLAs, and logistic aspects of network care. Improvement of network care concern agreements on diagnostic workup, use of SLA, Spoke participation in the MDT, and patient information exchange.

The impact of the COVID-19 pandemic on the diagnosis, stage, and treatment of esophagogastric cancer

BACKGROUND

The COVID-19 pandemic has affected the entire global healthcare system, including oncological care. This study investigated the effects of the COVID-19 pandemic on the diagnosis, stage, and treatment of esophagogastric cancer in the Netherlands.

METHODS

Patients diagnosed in 2020 were divided into 5 periods, based on the severity of the COVID-19 pandemic in the Netherlands, and compared to patients diagnosed in the same period in the years 2017-2019. Patient characteristics and treatments were evaluated for esophageal cancer (EC) and gastric cancer (GC) separately.

RESULTS

The number of esophagogastric cancer diagnoses decreased prominently during the first 2 months of the COVID-19 pandemic. During this period, a significantly higher percentage of GC patients was diagnosed with incurable disease (52.5% in 2017-2019 and 67.7% in 2020, p = 0.011). We observed a significant reduction in the percentage of patients with potentially curable EC treated with resection and neoadjuvant chemoradiotherapy (from 35.0% in 2017-2019 to 27.3% in 2020, p < 0.001). Also, patients diagnosed with incurable GC were treated less frequently with a resection (from 4.6% in 2017-2019 to 1.5% in 2020, p = 0.009) in the second half of 2020.

CONCLUSIONS

Compared to previous years, the number of esophagogastric cancer diagnoses decreased in the first 2 months of the COVID-19 pandemic, while an increased percentage of patients was diagnosed with incurable disease. Both in the curative and palliative setting, patients were less likely to be treated with a surgical resection.

Incidence, Stage, Treatment, and Survival of Noncardia Gastric Cancer

Importance

Gastric cancer is the fifth most common cancer worldwide, and investigating its incidence, characteristics, treatment, and outcomes over the past decades can help in selecting clinical strategies and future research directions.

Objective

To analyze the trends in incidence, staging, and treatment of gastric cancer.

Design, Setting, and Participants

This nationwide, population-based cohort study included patients diagnosed with noncardia gastric cancer (NCGC) between 1989 and 2021 in the Netherlands.

Main Outcomes and Measures

Differences in tumor characteristics, treatment, and survival were analyzed per fixed time periods (1989-1993, 1994-1998, 1999-2003, 2004-2008, 2009-2013, 2014-2018, and 2019-2021).

Results

In total, 47 014 patients (median [IQR] age, 73 [64-80] years; 28 032 [60%] male patients) were identified with mostly adenocarcinomas of the antrum region (when location was known). Age-standardized incidence decreased from 20.3 to 6.1 per 100 000 person-years between 1989 and 2021. During the study period, unknown T and N stages were recorded less frequently, and metastatic disease was diagnosed more frequently (1989-1993: 2633 of 9493 patients [28%]; 2019-2021: 1503 of 3200 patients [47%] in 2019-2021). Over time, fewer patients with metastatic disease underwent surgery with or without other treatment modalities (68% in 1989-1993 vs 64% in 2019-2021), and palliative chemotherapy in metastatic NCGC increased from 9% to 40%. For patients with nonmetastatic disease, 5-year relative survival improved from 28% (95% CI, 26.5%-29.2%) to 36% (95% CI, 33.5%-37.6%) between 1989 and 2021. For patients with nonmetastatic disease undergoing a resection, 5-year survival increased from 40% (95% CI, 38.3%-41.8%) to 51% (95% CI, 47.9%-53.3%). For patients with metastatic disease, 1-year relative survival increased from 10% (95% CI, 8.7%-11.1%) to 19% (95% CI, 17.2%-21.6%), but 3-year relative survival remained poor at 5% (95% CI, 3.6%-7.5%).

Conclusions and Relevance

In this nationwide cohort study involving 47 014 patients diagnosed with NCGC (1989-2021), the results showed a decrease in incidence, more accurate staging, a shift in treatment modalities, and improved patient survival.

[18F]FDG-PET-Based Personalized Radiotherapy Dose Prescription

PET imaging with 2'-deoxy-2'-[18F]fluoro-D-glucose ([18F]FDG) has become one of the pillars in the management of malignant diseases. It has proven value in diagnostic workup, treatment policy, follow-up, and as prognosticator for outcome. [18F]FDG is widely available and standards have been developed for PET acquisition protocols and quantitative analyses. More recently, [18F]FDG-PET is also starting to be appreciated as a decision aid for treatment personalization. This review focuses on the potential of [18F]FDG-PET for individualized radiotherapy dose prescription. This includes dose painting, gradient dose prescription, and [18F]FDG-PET guided response-adapted dose prescription. The current status, progress, and future expectations of these developments for various tumor types are discussed.

Dose coverage and breath-hold analysis of breast cancer patients treated with surface-guided radiotherapy

BACKGROUND

Surface-guided radiotherapy (SGRT) is used to ensure a reproducible patient set-up and for intra-fraction motion monitoring. The arm position of breast cancer patients is important, since this is related to the position of the surrounding lymph nodes. The aim of the study was to investigate the set-up accuracy of the arm of patients positioned using SGRT. Moreover, the actual delivered dose was investigated and an extensive breath-hold analysis was performed.

METHODS

84 patients who received local or locoregional breast radiation therapy were positioned and monitored using SGRT. The accuracy of the arm position, represented by the clavicle position, was studied on the anterior-posterior kV-image. To investigate the effect of changes in anatomy and patient set-up, the actual delivered dose was calculated on cone-beam CT-scans (CBCT). A deformable registration of the CT to the CBCT was applied to deform the structures of the CT onto the CBCT. The minimum dose in percentage of the prescribed dose that was received by 98% of different CTV volumes (D98) was determined. An extensive breath-hold analysis was performed and definitions for relevant parameters were given.

RESULTS

The arm position of 77 out of 84 patients in total was successful, based on the clavicle rotation. The mean clavicle rotation was 0.4° (± 2.0°). For 89.8% of the patients who were irradiated on the whole-breast D98 was larger than 95% of the prescribed dose (D98 > 95%). D98 > 95% applied for 70.8% of the patients irradiated on the chest wall. Concerning the lymph node CTVs, D98 > 95% for at least 95% of the patients. The breath-hold analysis showed a mean residual setup error of - 0.015 (± 0.90), - 0.18 (± 0.82), - 0.58 (± 1.1) mm in vertical, lateral, and longitudinal direction, respectively. The reproducibility and stability of the breath-hold was good, with median 0.60 mm (95% confidence interval (CI) [0.66-0.71] mm) and 0.20 mm (95% CI 0.21-0.23] mm), respectively.

CONCLUSIONS

Using SGRT we were able to position breast cancer patients successfully, with focus on the arm position. The actual delivered dose calculated on the CBCT was adequate and no relation between clavicle rotation and actual delivered dose was found. Moreover, breath-hold analysis showed a good reproducibility and stability of the breath-hold. Trial registration CCMO register NL69214.028.19.

Definition, diagnosis and treatment of oligometastatic oesophagogastric cancer: A Delphi consensus study in Europe

BACKGROUND

Local treatment improves the outcomes for oligometastatic disease (OMD, i.e. an intermediate state between locoregional and widespread disseminated disease). However, consensus about the definition, diagnosis and treatment of oligometastatic oesophagogastric cancer is lacking. The aim of this study was to develop a multidisciplinary European consensus statement on the definition, diagnosis and treatment of oligometastatic oesophagogastric cancer.

METHODS

In total, 65 specialists in the multidisciplinary treatment for oesophagogastric cancer from 49 expert centres across 16 European countries were requested to participate in this Delphi study. The consensus finding process consisted of a starting meeting, 2 online Delphi questionnaire rounds and an online consensus meeting. Input for Delphi questionnaires consisted of (1) a systematic review on definitions of oligometastatic oesophagogastric cancer and (2) a discussion of real-life clinical cases by multidisciplinary teams. Experts were asked to score each statement on a 5-point Likert scale. The agreement was scored to be either absent/poor (<50%), fair (50%-75%) or consensus (≥75%).

RESULTS

A total of 48 experts participated in the starting meeting, both Delphi rounds, and the consensus meeting (overall response rate: 71%). OMD was considered in patients with metastatic oesophagogastric cancer limited to 1 organ with ≤3 metastases or 1 extra-regional lymph node station (consensus). In addition, OMD was considered in patients without progression at restaging after systemic therapy (consensus). For patients with synchronous or metachronous OMD with a disease-free interval ≤2 years, systemic therapy followed by restaging to consider local treatment was considered as treatment (consensus). For metachronous OMD with a disease-free interval >2 years, either upfront local treatment or systemic treatment followed by restaging was considered as treatment (fair agreement).

CONCLUSION

The OMEC project has resulted in a multidisciplinary European consensus statement for the definition, diagnosis and treatment of oligometastatic oesophagogastric adenocarcinoma and squamous cell cancer. This can be used to standardise inclusion criteria for future clinical trials.

Locally Recurrent Rectal Cancer: Toward a Second Chance at Cure? A Population-Based, Retrospective Cohort Study

BACKGROUND

In current practice, rates of locally recurrent rectal cancer (LRRC) are low due to the use of the total mesorectal excision (TME) in combination with various neoadjuvant treatment strategies. However, the literature on LRRC mainly consists of single- and multicenter retrospective cohort studies, which are prone to selection bias. The aim of this study is to provide a nationwide, population-based overview of LRRC after TME in the Netherlands.

PATIENTS AND METHODS

In total, 1431 patients with nonmetastasized primary rectal cancer diagnosed in the first six months of 2015 and treated with TME were included from the nationwide, population-based Netherlands Cancer Registry. Data on disease recurrence were collected for patients diagnosed in these 6 months only. Competing risk cumulative incidence, competing risk regression, and Kaplan-Meier analyses were performed to assess incidence, risk factors, treatment, and overall survival (OS) of LRRC.

RESULTS

Three-year cumulative incidence of LRRC was 6.4%; synchronous distant metastases (LRRC-M1) were present in 44.9% of patients with LRRC. Distal localization, R1-2 margin, (y)pT3-4, and (y)pN1-2 were associated with an increased LRRC rate. No differences in LRRC treatment and OS were found between patients who had been treated with or without prior n(C)RT. Curative-intent treatment was given to 42.9% of patients with LRRC, and 3-year OS thereafter was 70%.

CONCLUSIONS

Nationwide LRRC incidence was low. A high proportion of patients with LRRC underwent curative-intent treatment, and OS of this group was high in comparison with previous studies. Additionally, n(C)RT for primary rectal cancer was not associated with differences in treatment and OS of LRRC.

Triplet Chemotherapy with Cisplatin versus Oxaliplatin in the CRITICS Trial: Treatment Compliance, Toxicity, Outcomes and Quality of Life in Patients with Resectable Gastric Cancer

(1) Background: Perioperative chemotherapy is the current standard treatment for patients with resectable gastric cancer. Based on studies in patients with metastatic gastric cancer, oxaliplatin has replaced cisplatin in the curative setting as well. However, evidence to prefer oxaliplatin over cisplatin in the curative setting is limited. (2) Methods: We compared patient-related and tumor-related outcomes for cisplatin versus oxaliplatin in patients with resectable gastric cancer treated with perioperative chemotherapy in the CRITICS trial. (3) Results: Preoperatively, 632 patients received cisplatin and 149 patients received oxaliplatin. Preoperative severe toxicity was encountered in 422 (67%) patients who received cisplatin versus 89 (60%) patients who received oxaliplatin (p = 0.105). Severe neuropathy was observed in 5 (1%) versus 6 (4%; p = 0.009) patients, respectively. Postoperative severe toxicity occurred in 109 (60%) versus 26 (51%) (p = 0.266) patients; severe neuropathy in 2 (1%) versus 2 (4%; p = 0.209) for patients who received cisplatin or oxaliplatin, respectively. Diarrhea impacted the quality of life more frequently in patients who received oxaliplatin compared to cisplatin. Complete or near-complete pathological response was achieved in 94 (21%) versus 16 (15%; p = 0.126) patients who received cisplatin or oxaliplatin, respectively. Overall survival was not significantly different in both groups (p = 0.300). (4) Conclusions: Both cisplatin and oxaliplatin are legitimate options as part of systemic treatment in patients with resectable gastric cancer.

Age-specific incidence, treatment, and survival trends in esophageal cancer: a Dutch population-based cohort study

BACKGROUND

Data on the age-specific incidence of esophageal cancer are lacking. Our aim was to investigate the age-stratified incidence, treatment, and survival trends of esophageal cancer in the Netherlands, with a focus on adults <50 years.

MATERIAL AND METHODS

Patients diagnosed with esophageal cancer were included from the nationwide Netherlands Cancer Registry (1989-2018). Follow-up data were available until 31 December 2018. Annual percentage changes of incidence were analyzed according to age group (<50, 50-74, and ≥75 years) and histology type: adenocarcinoma (EAC) and squamous cell carcinoma (ESCC). Treatment trends and relative survival rates (RSR) were estimated by age and stage grouping.

RESULTS

A total 59,584 patients were included. In adults <50 years, EAC incidence tripled (mean increase per year: males 1.5%, females 3%), while the incidence of ESCC decreased (mean decrease per year: males -5.3%, females -4.3%). Patients <50 years more often presented with advanced disease stages compared to older patients and were more likely to receive multimodality treatments. Most patients <50 years with potentially curable disease were treated with neoadjuvant chemoradiotherapy followed by surgery compared to patients 50-74 and ≥75 years (74% vs. 55% vs. 15%, respectively; p < .001), and received more frequent systemic therapy once staged with palliative disease (72% vs. 54% vs. 19%, respectively; p < .001). The largest RSR improvement was seen in patients <50 years with early-stage (five years: +47%), potentially curable (five years: +22%), and palliative disease (one year: +11%). Over time, a trend of increasing survival difference was seen between patients <50 and ≥75 years with potentially curable (five-year difference: 17% to 27%) and palliative disease (one-year difference: 11% to 20%).

CONCLUSION

The incidence of EAC is increasing in adults <50 years in the Netherlands. Differences in the use of multimodality treatments with curative or life-prolonging intent in different age categories may account for increasing survival gaps.

Quality of Life Is Associated With Survival in Patients With Gastric Cancer: Results From the Randomized CRITICS Trial

BACKGROUND

The evaluation of health-related quality of life (HRQoL) in clinical trials has become increasingly important because it addresses the impact of treatment from the patient's perspective. The primary aim of this study was to investigate the effect of postoperative chemotherapy and chemoradiotherapy (CRT) after neoadjuvant chemotherapy and surgery with extended (D2) lymphadenectomy on HRQoL in the CRITICS trial. Second, we investigated the potential prognostic value of pretreatment HRQoL on event-free survival (EFS) and overall survival (OS).

PATIENTS AND METHODS

Patients in the CRITICS trial were asked to complete HRQoL questionnaires (EORTC Quality-of-Life Questionnaire-Core 30 and Quality-of-Life Questionnaire gastric cancer-specific module) at baseline, after preoperative chemotherapy, after surgery, after postoperative chemotherapy or CRT, and at 12 months follow-up. Patients with at least 1 evaluable questionnaire (645 of 788 randomized patients) were included in the HRQoL analyses. The predefined endpoints included dysphagia, pain, physical functioning, fatigue, and Quality-of-Life Questionnaire-Core 30 summary score. Linear mixed modeling was used to assess differences over time and at each time point. Associations of baseline HRQoL with EFS and OS were investigated using multivariate Cox proportional hazards analyses.

RESULTS

At completion of postoperative chemo(radio)therapy, the chemotherapy group had significantly better physical functioning (P=.02; Cohen's effect size = 0.42) and less dysphagia (P=.01; Cohen's effect size = 0.38) compared with the CRT group. At baseline, worse social functioning (hazard ratio [HR], 2.20; 95% CI, 1.36-3.55; P=.001), nausea (HR, 1.89; 95% CI, 1.39-2.56; P<.001), worse WHO performance status (HR, 1.55; 95% CI, 1.13-2.13; P=.007), and histologic subtype (diffuse vs intestinal: HR, 1.94; 95% CI, 1.42-2.67; P<.001; mixed vs intestinal: HR, 2.35; 95% CI, 1.35-4.12; P=.003) were significantly associated with worse EFS and OS.

CONCLUSIONS

In the CRITICS trial, the chemotherapy group had significantly better physical functioning and less dysphagia after postoperative treatment. HRQoL scales at baseline were significantly associated with EFS and OS.

Response to neoadjuvant chemotherapy and survival in molecular subtypes of resectable gastric cancer: a post hoc analysis of the D1/D2 and CRITICS trials

BACKGROUND

Epstein-Barr virus positivity (EBV+) and microsatellite instability (MSI-high) are positive prognostic factors for survival in resectable gastric cancer (GC). However, benefit of perioperative treatment in patients with MSI-high tumors remains topic of discussion. Here, we present the clinicopathological outcomes of patients with EBV+, MSI-high, and EBV-/MSS GCs who received either surgery only or perioperative treatment.

METHODS

EBV and MSI status were determined on tumor samples collected from 447 patients treated with surgery only in the D1/D2 trial, and from 451 patients treated perioperatively in the CRITICS trial. Results were correlated to histopathological response, morphological tumor characteristics, and survival.

RESULTS

In the D1/D2 trial, 5-year cancer-related survival was 65.2% in 47 patients with EBV+, 56.7% in 47 patients with MSI-high, and 47.6% in 353 patients with EBV-/MSS tumors. In the CRITICS trial, 5-year cancer-related survival was 69.8% in 25 patients with EBV+, 51.7% in 27 patients with MSI-high, and 38.6% in 402 patients with EBV-/MSS tumors. Interestingly, all three MSI-high tumors with moderate to complete histopathological response (3/27, 11.1%) had substantial mucinous differentiation. No EBV+ tumors had a mucinous phenotype. 115/402 (28.6%) of EBV-/MSS tumors had moderate to complete histopathological response, of which 23/115 (20.0%) had a mucinous phenotype.

CONCLUSIONS

In resectable GC, MSI-high had favorable outcome compared to EBV-/MSS, both in patients treated with surgery only, and in those treated with perioperative chemo(radio)therapy. Substantial histopathological response was restricted to mucinous MSI-high tumors. The mucinous phenotype might be a relevant parameter in future clinical trials for MSI-high patients.

Prognostic value of tumor markers and ctDNA in patients with resectable gastric cancer receiving perioperative treatment: results from the CRITICS trial

AIM

To evaluate the prognostic value of tumor markers in a European cohort of patients with resectable gastric cancer.

METHODS

We performed a post hoc analysis of the CRITICS trial, in which 788 patients received perioperative therapy. Association between survival and pretreatment CEA, CA 19-9, alkaline phosphatase, neutrophils, hemoglobin and lactate dehydrogenase were explored in uni- and multivariable Cox regression analyses. Likelihoods to receive potentially curative surgery were investigated for patients without elevated tumor markers versus one of the tumor markers elevated versus both tumor markers elevated. The association between tumor markers and the presence of circulating tumor DNA (ctDNA) was explored in 50 patients with available ctDNA data.

RESULTS

In multivariable analysis, in which we corrected for allocated treatment and other baseline characteristics, elevated pretreatment CEA (HR 1.43; 95% CI 1.11-1.85, p < 0.001) and CA 19-9 (HR 1.79; 95% CI 1.42-2.25, p < 0.001) were associated with worse OS. Likelihoods to receive potentially curative surgery were 86%, 77% and 60% for patients without elevated tumor marker versus either elevated CEA or CA 19-9 versus both elevated, respectively (p < 0.001). Although both preoperative presence of ctDNA and tumor markers were prognostic for survival, no association was found between these two parameters.

CONCLUSION

CEA and CA 19-9 were independent prognostic factors for survival in a large cohort of European patients with resectable gastric cancer. No relationship was found between tumor markers and ctDNA. These factors could potentially guide treatment choices and should be included in future trials to determine their definitive position.

TRIAL REGISTRATION

ClinicalTrial.gov identifier: NCT00407186. EudraCT number: 2006-00413032.

Implementation of MR-linac and proton therapy in two radiotherapy departments in The Netherlands: Recommendations based on lessons learned

Recently, two new treatment techniques, i.e. proton therapy and MR-linac based radiotherapy (RT), have been introduced in Dutch RT centres with major impact on daily practice. The content and context of these techniques are frequently described in scientific literature while little is reported about the implementation phase. This process is complex due to a variety of aspects, such as the involvement of multiple stakeholders, significant unpredictability in the start-up phase, the impact of the learning curve, standard operating procedures under development, new catchment areas, and extensive training programs. Insight about implementation in daily care is utterly important for clinics that are about to introduce these new technologies in order to prevent that every centre needs to reinvent the wheel. This position paper gives an overview of the implementation of proton therapy and MR-linac based RT in two large academic RT centres in the Netherlands, i.e. Maastro and Radboudumc respectively. With this paper we aim to report our lessons learned, in order to facilitate other RT centres that consider introducing these and other new techniques in their departments.

ESTRO ACROP guidelines for the delineation of lymph nodal areas in upper gastrointestinal malignancies

The European SocieTy for Radiation and Oncology -Advisory Committee on Radiation Oncology Practice (ESTRO-ACROP) endorsed a project to provide guidelines (GL) for the identification and delineation of clinically negative lymph-nodal stations (LNs) involved in upper gastrointestinal clinical scenarios. The presented GL is focused on preoperative (or definitive) setting. The project aim is to improve the consistency of clinical target volume (CTV) delineation by providing: a description of the anatomical boundaries of the LNs; a radiological computed tomography-based atlas depicting the LNs areas; a free, web-based, interactive example case for independent training of radiation oncologists on LNs delineation according to the presented GL, by both qualitative and quantitative analysis (through the FALCON EduCase platform). This project was carried out with the intention to facilitate and improve uniformity of future upper gastrointestinal guidelines on nodal CTV delineation. We report methodology and results from the collaboration of a working group panel selected by the ESTRO-ACROP.

Risk Factors for Metachronous Isolated Peritoneal Metastasis after Preoperative Chemotherapy and Potentially Curative Gastric Cancer Resection: Results from the CRITICS Trial

Simple Summary

Around 20% of gastric cancer patients develop peritoneal metastasis after preoperative chemotherapy and curative surgery. Patients with peritoneal metastasis as a single site of metastasis may potentially benefit from prophylactic strategies. In this post-hoc analysis of the international phase III CRITICS trial, we aim to identify factors that can distinguish patients at high risk for developing peritoneal metastasis as a single site. Diffuse or mixed histological subtype, tumors with serosal involvement (ypT4) and advanced lymph node stage (ypN3 or a tumor positive lymph node ratio >20%) were independent risk factors for isolated peritoneal metastasis after preoperative chemotherapy and curative surgery. The combination of these risk factors identifies a subgroup that may benefit from treatment strategies that aim to prevent peritoneal metastasis.

Abstract

Gastric cancer (GC) patients at high risk of developing peritoneal metastasis (PM) as a single site of metastasis after curative treatment may be candidates for adjuvant prophylactic strategies. Here we investigated risk factors for metachronous isolated PM in patients who were treated in the CRITICS trial (NCT00407186). Univariable and multivariable analyses on both metachronous isolated PM and ‘other events’, i.e., (concurrent) distant metastasis, locoregional recurrence or death, were performed using a competing risk model and summarized by cumulative incidences. Isolated PM occurred in 64 of the 606 (11%) included patients. Diffuse or mixed histological subtype, ypT4 tumor stage and LN^high (ypN3 lymph node stage or a lymph node ratio >20%) were independent risk factors for isolated PM in both univariable and multivariable analyses. Likewise, LN^high was an independent risk factor for ‘other events’. Patients with tumors who were positive for all three independent risk factors had the highest two-year cumulative incidence of 43% for isolated PM development. In conclusion, diffuse or mixed histological subtype, ypT4 and LN^high were identified as independent risk factors for isolated PM in patients treated with preoperative chemotherapy followed by surgical resection. The combination of these factors may identify a subgroup that may benefit from PM-preventing treatment strategies.

Poor response at restaging MRI and high incomplete resection rates of locally advanced mucinous rectal cancer after chemoradiation therapy

AIM

Mucinous carcinoma is a histological subtype of rectal cancer and has been associated with a poor response to neoadjuvant chemoradiotherapy (CRT). The primary aim of this study was to analyse the response on MRI of mucinous locally advanced rectal cancer (LARC) after CRT compared to regular adenocarcinoma.

METHOD

Patients with LARC (defined as cT4 and/or cN2), who underwent CRT followed by restaging MRI and surgery in two tertiary referral hospitals were retrospectively included in the study. Pre- and post-treatment MRI was reviewed by an experienced abdominal radiologist.

RESULTS

A total of 102 patients, of whom 29 were diagnosed with mucinous carcinoma, were included for analysis. At restaging MRI, adenocarcinoma patients demonstrated significantly less clinical involvement of the mesorectal fascia (37% vs. 62%, P = 0.003) while this was not demonstrated in mucinous carcinoma patients (86% vs. 97%, P = 0.16). Significant downstaging after CRT in adenocarcinoma patients (P = 0.01) was seen while, in mucinous carcinoma patients, no downstaging after CRT (P = 0.89) was seen. Pathology revealed significantly higher rates of an involved circumferential resection margin in mucinous carcinoma versus adenocarcinoma patients (27.6% vs. 1.4%; P < 0.001). After multivariate regression analysis, mucinous carcinoma remained an independent prognostic factor for local recurrence (hazard ratio 3.6; 95% CI 1.1-12.4), although no differences in overall or disease-free survival were observed.

CONCLUSION

Mucinous rectal carcinoma is associated with a poor clinical response at restaging MRI after CRT, leading to relatively higher rates of involved circumferential resection margins at pathology. In this cohort, mucinous carcinoma seems to be a prognostic factor for increased risk of local recurrence, without an effect on overall survival.

Abstract 354: Mucinous phenotype is associated with response to neoadjuvant chemotherapy in microsatellite instable resectable gastric cancer

Background: Epstein-Barr virus positivity (EBV+) and microsatellite instability (MSI-high) have been shown to be positive prognostic factors for long term survival in resectable gastric cancer (GC) in several studies. However, the benefit of perioperative treatment in patients with MSI-high tumors remains topic of discussion. Here, we present the clinicopathological outcome of patients with EBV+ and MSI-high GCs treated with surgery only in the Dutch D1/D2 trial, and treated with chemotherapy or chemoradiotherapy after preoperative chemotherapy and surgery in the CRITICS trial.

Patients and methods: EBV was determined in tumor tissue using EBV-encoded RNA in situ hybridization (EBER-ISH). PCR and/or immunohistochemistry were performed to determine MSI status. Results were correlated to histopathological response, morphological tumor characteristics and survival.

Results: In the Dutch D1/D2 trial 10.5% (47/447) of tumors were EBV+ and 10.5% (47/447) were MSI-high. In the CRITICS trial 5.5% (25/451) of tumors were EBV+ and 5.5% (25/451) were MSI-high tumors. In the Dutch D1/D2 trial, five-year overall survival probability was 51.1% for EBV+, 46.8% for MSI-high, and 42.5% for EBV-/MSS (P=0.19). In the CRITICS trial, five-year overall survival was 56.0% for EBV+, 47.3% for MSI-high, and 36.5% for EBV-/MSS (P=0.22). In the CRITICS trial, 3 (12.5%) MSI-high tumors showed moderate to complete histopathological response. Interestingly, all three showed a mucinous phenotype. Eight (36.4%) EBV+ and 114 (29.9%) EBV-/MSS tumors showed moderate to complete histopathological response. None of the EBV+ GCs showed mucinous differentiation.

Conclusions: The favorable outcome of GC patients with resectable EBV+ or MSI-high tumors compared to EBV-/MSS tumors remains after perioperative chemotherapy. In MSI-high tumors significant histopathological response to neoadjuvant chemotherapy was found only in those with a mucinous phenotype.

Citation Format: H.D. Biesma, A.T.T.D. Soeratram, K. Sikorska, I.A. Caspers, H.F. van Essen, J.M.P. Egthuijsen, A. Mookhoek, D.M. Hoek, W. Vos, H.W.M. van Laarhoven, M. Nordsmark, D.L. van der Peet, F.A.R.M. Warmerdam, M.M. Geenen, O.J.L. Loosveld, J.E.A. Portielje, M. Los, E. Meershoek - Klein Kranenbarg, H.H. Hartgrink, J. van Sandick, C.J.H. van de Velde, M. Verheij, A. Cats, B. Ylstra, N.C.T. van Grieken, On behalf of the CRITICS investigators. Mucinous phenotype is associated with response to neoadjuvant chemotherapy in microsatellite instable resectable gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 354.

The prognostic value of tumor markers in patients (pts) with resectable gastric cancer (GC) receiving perioperative therapy in the CRITICS trial

4024

Background: Carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9 are well-known tumor markers. Most studies on CEA and CA 19-9 in pts with GC were performed in Asia, and/or in the metastatic setting. The aim of this study was to investigate the prognostic value of blood derived laboratory parameters in a cohort of European pts with resectable non-metastatic GC. Methods: In the CRITICS trial, 788 pts with resectable GC underwent perioperative therapy (preoperative chemotherapy plus either postoperative chemotherapy or postoperative chemoradiotherapy). Blood levels of CEA, CA 19-9, alkaline phosphatase (AP), creatinine, neutrophils, hemoglobin (Hb) and lactate dehydrogenase (LDH) were determined prior to treatment. Data for these variables were available for at least 89% of the pts. Factors significant on univariable cox regression analysis were further explored in multivariable analysis. Probabilities to undergo potentially curative surgery was investigated for factors significant on multivariable analysis. The relationship between tumor markers and the presence of circulating tumor DNA (ctDNA) was explored in 50 pts with available ctDNA data. Results: CEA and CA 19-9 were identified as independent prognostic factors for survival (Table). Probabilities to undergo potentially curative surgery were 86%, 77% and 60% for pts with no elevated tumor makers versus those with elevated CEA or elevated CA 19-9 versus those with both tumor markers elevated, respectively (p<0.001). No relationship was found between elevated tumor marker(s) and the presence of ctDNA neither pretreatment nor preoperatively. Conclusions: Pretreatment blood levels of CEA and CA 19-9 were identified as prognostic factors for overall survival in a large cohort of European GC pts with potentially curable disease. These factors may guide treatment choices at an early phase and should be included in future trials to determine their role in clinical decision making.[Table: see text]

Risk factors of metachronous peritoneal carcinomatosis after potentially curative gastric cancer resection in the CRITICS trial

4053

Background: Peritoneal carcinomatosis (PC) is accountable for over 50% of metastatic spread in gastric cancer (GC). Little is known about factors contributing to the risk of metachronous PC as a single site of metastases after preoperative chemotherapy and potentially curative resection. An accurate prediction model of risk factors identifying high risk populations may pave the way for new treatment strategies, such as intraperitoneal chemotherapy. In this analysis, risk factors for the development of isolated metachronous PC after preoperative chemotherapy and surgical resection were investigated. Methods: In the CRITICS trial, 788 patients with resectable GC were randomized for preoperative chemotherapy and gastrectomy followed by either chemotherapy or chemoradiotherapy. Patients who underwent a potentially curative resection without peritoneal metastases at time of surgery were included in this analysis. Univariate and multivariate analyses were performed using a competing risk model. Results: In total, 617 patients met the inclusion criteria. Overall, 97 of 617 (16%) patients developed metachronous PC. The peritoneum was the first site of recurrence in 64 of 617 (10%) patients. Diffuse or mixed type GC, ypT4 stage and ypN3 stage or a lymph node ratio (LNR) with >20% tumor positivity were independent predictors of isolated PC in both univariate and multivariate analyses with hazard ratios (HR) of 2.90, 2.63 and 2.31, respectively (Table). ypT4 and ypN3 stage or a LNR >20% were also independent predictors of distant recurrence or death with HR of 1.46 and 2.34, respectively. Patients in whom all predictors were present had the highest 2 year cumulative incidences of both isolated PC development and other events of 39.6% and 48.8%, respectively. Conclusions: Diffuse or mixed tumor type, ypT4 and ypN3 or a LNR >20% were identified as independent risk factors for metachronous PC as a single site of metastases in a large cohort of patients treated with preoperative chemotherapy followed by surgical resection. The combination of these factors might identify a subgroup that could benefit from preventive treatment strategies.[Table: see text]

Immune Modulation Plus Tumor Ablation: Adjuvants and Antibodies to Prime and Boost Anti-Tumor Immunity In Situ

In situ tumor ablation techniques, like radiotherapy, cryo- and heat-based thermal ablation are successfully applied in oncology for local destruction of tumor masses. Although diverse in technology and mechanism of inducing cell death, ablative techniques share one key feature: they generate tumor debris which remains in situ. This tumor debris functions as an unbiased source of tumor antigens available to the immune system and has led to the concept of in situ cancer vaccination. Most studies, however, report generally modest tumor-directed immune responses following local tumor ablation as stand-alone treatment. Tumors have evolved mechanisms to create an immunosuppressive tumor microenvironment (TME), parts of which may admix with the antigen depot. Provision of immune stimuli, as well as approaches that counteract the immunosuppressive TME, have shown to be key to boost ablation-induced anti-tumor immunity. Recent advances in protein engineering have yielded novel multifunctional antibody formats. These multifunctional antibodies can provide a combination of distinct effector functions or allow for delivery of immunomodulators specifically to the relevant locations, thereby mitigating potential toxic side effects. This review provides an update on immune activation strategies that have been tested to act in concert with tumor debris to achieve in situ cancer vaccination. We further provide a rationale for multifunctional antibody formats to be applied together with in situ ablation to boost anti-tumor immunity for local and systemic tumor control.

To 1000 Gy and back again: a systematic review on dose-response evaluation in selective internal radiation therapy for primary and secondary liver cancer

Purpose

To systematically review all current evidence into the dose-response relation of yttrium-90 and holmium-166 selective internal radiation therapy (SIRT) in primary and secondary liver cancer.

Methods

A standardized search was performed in PubMed (MEDLINE), Embase, and the Cochrane Library in order to identify all published articles on dose-response evaluation in SIRT. In order to limit the results, all articles that investigated SIRT in combination with other therapy modalities (such as chemotherapy) were excluded.

Results

A total of 3038 records were identified of which 487 were screened based on the full text. Ultimately, 37 studies were included for narrative analysis. Meta-analysis could not be performed due to the large heterogeneity in study and reporting designs. Out of 37 studies, 30 reported a ‘mean dose threshold’ that needs to be achieved in order to expect a response. This threshold appears to be higher for hepatocellular carcinoma (HCC, 100–250 Gy) than for colorectal cancer metastases (CRC, 40–60 Gy). Reported thresholds tend to be lower for resin microspheres than when glass microspheres are used.

Conclusion

Although the existing evidence demonstrates a dose-response relationship in SIRT for both primary liver tumours and liver metastases, many pieces of the puzzle are still missing, hampering the definition of standardized dose thresholds. Nonetheless, most current evidence points towards a target mean dose of 100–250 Gy for HCC and 40–60 Gy for CRC. The field would greatly benefit from a reporting standard and prospective studies designed to elucidate the dose-response relation in different tumour types.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-021-05340-0.

Phase I and Pharmacologic Study of Olaparib in Combination with High-dose Radiotherapy with and without Concurrent Cisplatin for Non-Small Cell Lung Cancer

PURPOSE

To identify an MTD of olaparib, a PARP inhibitor, in combination with loco-regional radiotherapy with/without cisplatin for the treatment of non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

Olaparib dose was escalated in two groups: radiotherapy (66 Gy/24 fractions in 2.75 Gy/fraction) with and without daily cisplatin (6 mg/m²), using time-to-event continual reassessment method with a 1-year dose-limiting toxicity (DLT) period. The highest dose level with a DLT probability <15% was defined as MTD. Poly ADP-ribose (PAR) inhibition and radiation-induced PAR-ribosylation (PARylation) were determined in peripheral blood mononuclear cells.

RESULTS

Twenty-eight patients with loco-regional or oligometastatic disease (39%) were treated: 11 at olaparib 25 mg twice daily and 17 at 25 mg once daily. The lowest dose level with cisplatin was above the MTD due to hematologic and late esophageal DLT. The MTD without cisplatin was olaparib 25 mg once daily. At a latency of 1-2.8 years, severe pulmonary adverse events (AE) were observed in 5 patients across all dose levels, resulting in 18% grade 5 pulmonary AEs. Exploratory analyses indicate an association with the radiation dose to the lungs. At the MTD, olaparib reduced PAR levels by more than 95% and abolished radiation-induced PARylation. Median follow-up of survivors was 4.1 years. Two-year loco-regional control was 84%, median overall survival in patients with locally advanced NSCLC was 28 months.

CONCLUSIONS

Combined mildly hypofractionated radiotherapy and low-dose daily cisplatin and olaparib was not tolerable due to esophageal and hematologic toxicity. Severe pulmonary toxicity was observed as well, even without cisplatin. More conformal radiotherapy schedules with improved pulmonary and esophageal sparing should be explored.

MR-Guided Radiotherapy: The Perfect Partner for Immunotherapy?

During the last years, preclinical and clinical studies have emerged supporting the rationale to integrate radiotherapy and immunotherapy. Radiotherapy may enhance the effects of immunotherapy by improving tumor antigen release, antigen presentation, and T-cell infiltration. Recently, magnetic resonance guided radiotherapy (MRgRT) has become clinically available. Compared to conventional radiotherapy techniques, MRgRT firstly allows for daily on-table treatment adaptation, which enables both dose escalation for increasing tumor response and superior sparing of radiosensitive organs-at-risk for reducing toxicity. The current review focuses on the potential of combining MR-guided adaptive radiotherapy with immunotherapy by providing an overview on the current status of MRgRT, latest developments in preclinical and clinical radio-immunotherapy, and the unique opportunities and challenges for MR-guided radio-immunotherapy. MRgRT might especially assist in answering open questions in radio-immunotherapy regarding optimal radiation dose, fractionation, timing of immunotherapy, appropriate irradiation volumes, and response prediction.

Towards Personalization in the Curative Treatment of Gastric Cancer

Gastric cancer is the fifth most common cancer worldwide and has a high mortality rate. In the last decades, treatment strategy has shifted from an exclusive surgical approach to a multidisciplinary strategy. Treatment options for patients with resectable gastric cancer as recommended by different worldwide guidelines, include perioperative chemotherapy, pre- or postoperative chemoradiotherapy and postoperative chemotherapy. Although gastric cancer is a heterogeneous disease with respect to patient-, tumor-, and molecular characteristics, the current standard of care is still according to a one-size-fits-all approach. In this review, we discuss the background of the different treatment strategies in resectable gastric cancer including the current standard, the specific role of radiotherapy, and describe the current areas of research and potential strategies for personalization of therapy.

Adjuvant chemotherapy is superior to chemoradiation after D2 surgery for gastric cancer in the per-protocol analysis of the randomized CRITICS trial

BACKGROUND

The Intergroup 0116 and the MAGIC trials changed clinical practice for resectable gastric cancer in the Western world. In these trials, overall survival improved with post-operative chemoradiotherapy (CRT) and perioperative chemotherapy (CT). Intention-to-treat analysis in the CRITICS trial of post-operative CT or post-operative CRT did not show a survival difference. The current study reports on the per-protocol (PP) analysis of the CRITICS trial.

PATIENTS AND METHODS

The CRITICS trial was a randomized, controlled trial in which 788 patients with stage Ib-Iva resectable gastric or esophagogastric adenocarcinoma were included. Before start of preoperative CT, patients from the Netherlands, Sweden and Denmark were randomly assigned to receive post-operative CT or CRT. For the current analysis, only patients who started their allocated post-operative treatment were included. Since it is uncertain that the two treatment arms are balanced in such PP analysis, adjusted proportional hazards regression analysis and inverse probability weighted analysis were used to minimize the risk of selection bias and to estimate and compare overall and event-free survival.

RESULTS

Of the 788 patients, 478 started post-operative treatment according to protocol, 233 (59%) patients in the CT group and 245 (62%) patients in the CRT group. Patient and tumor characteristics between the groups before start of the post-operative treatment were not different. After a median follow-up of 6.7 years since the start of post-operative treatment, the 5-year overall survival was 57.9% (95% confidence interval: 51.4% to 64.3%) in the CT group versus 45.5% (95% confidence interval: 39.2% to 51.8%) in the CRT group (adjusted hazard ratio CRT versus CT: 1.62 (1.24-2.12), P = 0.0004). Inverse probability weighted analysis resulted in similar hazard ratios.

CONCLUSION

After adjustment for all known confounding factors, the PP analysis of patients who started the allocated post-operative treatment in the CRITICS trial showed that the CT group had a significantly better 5-year overall survival than the CRT group (NCT00407186).

Sensitization of drug resistant sarcoma tumors by membrane modulation via short chain sphingolipid-containing nanoparticles

Nanoparticles such as liposomes are able to overcome cancer treatment challenges such as multidrug resistance by increasing the bioavailability of the encapsulated drug, bypassing drug pumps or through targeting resistant cells. Here, we merge enhanced drug delivery by nanotechnology with tumor cell membrane modulation combined in a single formulation. This is achieved through the incorporation of Short chain sphingolipids (SCSs) in the liposomal composition, which permeabilizes cell membranes to amphiphilic drugs such as Doxorubicin (Dxr). To study the mechanism and capability of SCS-containing nanodevices to overcome Dxr resistance, a sensitive uterine sarcoma cell line, MES-SA, and a resistant derived cell line, MES-SA/MX2, were used. The mechanism of resistance was explored by lipidomics and flow cytometry, revealing significant differences in lipid composition and in P glycoprotein (Pgp) expression. In vitro assays show that SCS liposomes were able to reverse cell resistance, and importantly, display a higher net effect on resistant than sensitive cells. SCS lipids modulated the cell membrane of MES-SA/MX2 drug resistant cells, while Pgp expression was not affected. Furthermore, SCS-modified liposomes were evaluated in a sarcoma xenograft model on drug accumulation, pharmacokinetics and efficacy. SCS liposomes improved Dxr levels in tumor nuclei of MES-SA/MX2 tumor cells, which was accompanied by a delay in tumor growth of the resistant model. Here we show that Dxr accumulation in tumor cells by SCS-modified liposomes was especially improved in Dxr resistant cells, rendering Dxr as effective as in sensitive cells. Moreover, this phenomenon translated to improved efficacy when Dxr liposomes where modified with SCSs in the drug resistant tumor model, while no benefit was seen in the sensitive tumors.

Venous thromboembolism during preoperative chemotherapy in the CRITICS gastric cancer trial

BACKGROUND

The occurrence of a venous thromboembolism (VTE) is common in patients with cancer. Gastric cancer has been associated with one of the highest risks for VTE. Chemotherapy, especially cisplatin has been associated with a high VTE risk. In this study, risk factors for VTE occurrence and their potential impact on subsequent therapeutic interventions were investigated in patients who underwent preoperative chemotherapy, in the CRITICS gastric cancer trial.

PATIENTS AND METHODS

Patients with resectable gastric cancer were preoperatively treated with three cycles of 3-weekly epirubicin, cisplatin or oxaliplatin, and capecitabine (ECC/EOC). VTE was defined as any thrombus in the venous system, excluding superficial and/or device related VTEs. Potential risk factors were analyzed in a multivariable regression model with age, gender, Body Mass Index (BMI), tumor localization, Lauren classification, type of chemotherapy (ECC/EOC), (cardiovascular) comorbidity, and previous VTE as independent risk factors. The impact of VTE on completion rate of preoperative chemotherapy, surgical resection rate, postoperative complications, and start of postoperative therapy were investigated.

RESULTS

Of 781 patients, 78 (10%) of 781 patients developed a VTE during preoperative chemotherapy. On multivariable analysis, BMI ≥ 30 kg/m² and previous VTE were associated with VTE occurrence (reference BMI < 25 kg/m² ; OR 2.190; 95% CI 1.152-4.164; P = .017/previous VTE; OR 3.617; 95% CI 1.201-10.890; P = .022). Treatment with cisplatin was, compared to oxaliplatin, not significantly associated with VTE occurrence (OR 1.535; 95% CI 0.761-3.094; P = .231). VTE occurrence did not affect completion of preoperative chemotherapy, surgical resection rate, postoperative complications, or start of postoperative therapy.

CONCLUSION

High BMI and previous VTE were independent risk factors for VTE occurrence during preoperative chemotherapy in patients with resectable gastric cancer. VTE occurrence in the preoperative setting did not affect receipt of further treatment.

Impact of the coronavirus disease 2019 pandemic on cancer treatment: the patients' perspective

Background

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2, has inevitable consequences for medical care of patients without COVID-19. To assess the impact of this pandemic on oncological care, a nationwide survey was conducted among patients with cancer in the Netherlands.

Methods

The patients' perspective on oncological care was investigated using an online survey between March 29th 2020 and April 18th 2020. The survey consisted of 20 questions on four topics: patients’ characteristics, contact with the hospital, consequences of the COVID-19 pandemic and concerns about COVID-19.

Results

Five thousand three hundred two patients with cancer completed this nationwide survey. Overall, 30% of patients reported consequences for their oncological treatment or follow-up. In the majority of cases, this resulted in conversion from hospital visit to consultation by phone or video. The most frequently adjusted treatments were chemotherapy (30%) and immunotherapy (32%). Among patients with delay and discontinuation of treatment, 55% and 63% of patients, respectively, were (very) concerned about these consequences of the COVID-19 pandemic. Consequences were independent of regional differences in COVID-19 incidence. However, patients in regions with high COVID-19 incidence were significantly more concerned.

Conclusion

This is the first study investigating perspectives of patients with cancer during the COVID-19 pandemic. The study demonstrates the significant impact of the COVID-19 crisis on oncological care, indicating the need for psycho-oncological support during this pandemic.

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Impact of COVID-19 on oncological care from cancer patients’ perspective.

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5302 patients with cancer completed a nationwide online survey.

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30% of the patients reported consequences for oncological treatment or follow-up.

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The consequences were independent of regional differences in COVID-19 incidence.

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This study indicates the need for psycho-oncological support during this pandemic.

Enhancing radiation response by a second-generation TRAIL receptor agonist using a new in vitro organoid model system

•

We evaluated the effect of the second-generation TRAIL receptor agonist APG-880 on radiation-induced cytotoxicity.

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The combined effect was studied in short-term and long-term cytotoxicity assays in established CRC cell lines, and tumor organoids derived from colon cancer patients.

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We observed a supra-additive effect on cytotoxicity when APG-880 and radiation were combined simultaneously, with combination indices around 0.7.

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In long-term survival assays, we demonstrated a radiosensitizing effect of APG-880 with dose enhancement factors between 1.3 and 1.5.

Background

For many cancer types, including colorectal carcinoma (CRC), combined modality treatments have shown to improve outcome, but are frequently associated with significant toxicity, illustrating the need for new therapeutic approaches. Based on preclinical data, TRAIL receptor agonists appeared to be promising agents for cancer therapy especially in combination with DNA damaging regimens. Here, we present the combination of the second-generation TRAIL receptor agonist APG-880 with radiation in a new and clinically relevant 3D model system.

Methods

To investigate the effect of APG-880 in combination with radiation we performed short-term cytotoxicity and long-term clonogenic survival assays in established CRC cell lines, and in tumor organoids derived from colon cancer patients.

Results

APG-880 is a potent inducer of apoptosis in CRC cell lines and in patient-derived CRC organoids. Furthermore, a supra-additive effect on cytotoxicity was found when APG-880 and radiation were combined simultaneously, with combination indices around 0.7. Lastly, in the long-term survival assays, we demonstrated a radiosensitizing effect of APG-880 with dose enhancement factors between 1.3 and 1.5.

Conclusions

In a new, clinically relevant CRC-organoid model system we demonstrated a more than additive combined effect between the second-generation TRAIL receptor agonist APG-880 and radiation.

A head-to-head comparison between two commercial software packages for hybrid dosimetry after peptide receptor radionuclide therapy

Background

Dosimetry after peptide receptor radionuclide therapy (PRRT) is increasing; however, comparing or pooling of dosimetric results can be challenging since different approaches are used. The aim of this study was to perform a head-to-head comparison of post-PRRT curve fitting and dosimetry obtained from two commercial software Hybrid Viewer Dosimetry and PLANET Dose.

Methods

Post-therapy imaging included planar scintigraphy at 0.5, 4, 24 and 72 h post-injection of [¹⁷⁷Lu]Lu-DOTA-TATE for kinetics and SPECT/CT at 24 h for quantification. On planar imaging, 2 cm regions-of-interest were positioned within the inferior pole of the kidneys and kidney cortex was segmented on low-dose CT. On both planar and SPECT/CT, 2 cm spheres were positioned in the proximal humerus (red marrow equivalent) and in the region with the highest uptake in tumour lesions. TACs were estimated with mono- and bi-exponential fits in both software systems, after which tissue absorbed (kidney, red marrow, tumour) and biological effective doses (kidney) were calculated. Agreement-ICC, Spearman correlation and Bland-Altman plots were used to compare results.

Results

Mono-exponential fits showed the most comparable correlation between the measured and fitted data between both software. The ICC between absorbed dose outcomes was > 0.7 in tumour lesions and kidneys, but negative for the red marrow. Spearman correlation was > 0.9 for mono-exponential fits in kidneys and tumour lesions, and −0.7 in red marrow. Bi-exponential fits resulted in lower correlations and agreement values. Concordance between both software packages concerning the number of PRRT cycles with 7.4 GBq was observed based on a biological effective dose limit of 27 Gy to the kidneys.

Conclusion

[¹⁷⁷Lu]Lu-DOTA-TATE dosimetry results of two software packages were comparable in the same dataset, despite the limited number of imaging time-points. However, these results should be verified in a larger cohort before pooling of clinical data, as the obtained results will depend on acquisition protocol, timing and lesions definition.

Epithelial-to-mesenchymal transition is a prognostic marker for patient outcome in advanced stage HNSCC patients treated with chemoradiotherapy

BACKGROUND

The prognosis of patients with HPV-negative advanced stage head and neck squamous cell carcinoma (HNSCC) remains poor. No prognostic markers other than TNM staging are routinely used in clinic. Epithelial-to-mesenchymal transition (EMT) has been shown to be a strong prognostic factor in other cancer types. The purpose of this study was to determine the role of EMT in HPV-negative HNSCC outcomes.

METHODS

Pretreatment tumor material from patients of two cohorts, totalling 174 cisplatin-based chemoradiotherapy treated HPV-negative HNSCC patients, was RNA-sequenced. Seven different EMT gene expression signatures were used for EMT status classification and generation of HNSCC-specific EMT models using Random Forest machine learning.

RESULTS

Mesenchymal classification by all EMT signatures consistently enriched for poor prognosis patients in both cohorts of 98 and 76 patients. Uni- and multivariate analyses show important HR of 1.6-5.8, thereby revealing EMT's role in HNSCC outcome. Discordant classification by these signatures prompted the generation of an HNSCC-specific EMT profile based on the concordantly classified samples in the first cohort (cross-validation AUC > 0.98). The independent validation cohort confirmed the association of mesenchymal classification by the HNSCC-EMT model with poor overall survival (HR = 3.39, p < 0.005) and progression free survival (HR = 3.01, p < 0.005) in multivariate analysis with TNM. Analysis of an additional HNSCC cohort from PET-positive patients with metastatic disease prior to treatment further supports this relationship and reveals a strong link of EMT to the propensity to metastasize.

CONCLUSIONS

EMT in HPV-negative HNSCC co-defines patient outcome after chemoradiotherapy. The generated HNSCC-EMT prediction models can function as strong prognostic biomarkers.

Ovarian cancer-derived copy number alterations signatures are prognostic in chemoradiotherapy-treated head and neck squamous cell carcinoma

DNA copy number alterations (CNAs) are frequent in cancer, and recently developed CNA signatures revealed their value in molecular tumor stratification for patient prognosis and platinum resistance prediction in ovarian cancer. Head and neck squamous cell carcinoma (HNSCC) is also characterized by high CNAs. In this study, we determined CNA in 173 human papilloma virus-negative HNSCC from a Dutch multicenter cohort by low-coverage whole genome sequencing and tested the prognostic value of seven cancer-derived CNA signatures for these cisplatin- and radiotherapy-treated patients. We find that a high CNA signature 1 (s1) score is associated with low values for all other signatures and better patient outcomes in the Dutch cohorts and The Cancer Genome Atlas HNSCC data set. High s5 and s7 scores are associated with increased distant metastasis rates and high s6 scores with poor overall survival. High cumulative cisplatin doses result in improved outcomes in chemoradiotherapy-treated HNSCC patients. Here we find that tumors high in s1 or low in s6 are most responsive to a change in cisplatin dose. High s5 values, however, significantly increase the risk for metastasis in patients with low cumulative cisplatin doses. Together this suggests that the processes causing these CNA signatures affect cisplatin response in HNSCC. In conclusion, CNA signatures derived from a different cancer type were prognostic and associated with cisplatin response in HNSCC, suggesting they represent underlying molecular processes that define patient outcome.

Older versus younger adults with gastric cancer receiving perioperative treatment: Results from the CRITICS trial

AIM

To evaluate treatment-related toxicity, treatment compliance, surgical complications and event-free survival (EFS) in older (≥70 years) versus younger (<70 years) adults who underwent perioperative treatment for gastric cancer.

METHODS

In the CRITICS trial, 788 patients with resectable gastric cancer were randomised before start of any treatment and received preoperative chemotherapy (3 cycles of epirubicin, cisplatin or oxaliplatin and capecitabine), followed by surgery, followed by either postoperative chemotherapy or chemoradiotherapy (45Gy + cisplatin + capecitabine).

RESULTS

172 (22%) patients were older adults. During preoperative chemotherapy, 131 (77%) older adults versus 380 (62%) younger adults experienced severe toxicity (p < 0.001); older adults received significantly lower relative dose intensities (RDIs) for all chemotherapeutic drugs. Equal proportions of older versus younger adults underwent curative surgery: 137 (80%) versus 499 (81%), with comparable postoperative complications and postoperative mortality. Postoperative therapy after curative surgery started in 87 (64%) older adults versus 391 (78%) younger adults (p < 0.001). Incidence of severe toxicity during postoperative chemotherapy was 22 (54%) in older adults versus 113 (59%) in younger adults (p = 0.541); older adults received significantly lower RDIs for all chemotherapeutic drugs. Severe toxicity rates for postoperative chemoradiotherapy were 22 (48%) older adults versus 89 (45%) for younger adults (p = 0.703), with comparable chemotherapy RDIs and radiotherapy dose. Two-year EFS was 53% for older adults versus 51% for younger adults.

CONCLUSION

Perioperative treatment compliance, especially in the postoperative phase, was poorer in older adults compared with younger adults. As comparable proportions of patients underwent curative surgery, future studies should focus on neo-adjuvant treatment.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00407186. EudraCT number: 2006-00413032.

Mesothelioma Cells Depend on the Antiapoptotic Protein Bcl-xL for Survival and Are Sensitized to Ionizing Radiation by BH3-Mimetics

PURPOSE

The incidence of mesothelioma continues to rise and prognosis remains dismal owing to resistance to conventional therapies and few novel treatment options. Failure to activate apoptotic cell death is a resistance mechanism that may be overcome by inhibition of antiapoptotic Bcl-2 proteins using BH3-mimetic drugs. We investigated the role of antiapoptotic proteins in the radioresistance of mesothelioma, identifying clinically relevant targets for radiosensitization and evaluating the activity of BH3-mimetics alone and in combination with radiation therapy in preclinical models.

METHODS, MATERIALS AND RESULTS

Mesothelioma cell lines 211H, H2052, and H226 exposed to BH3-mimetics demonstrated Bcl-xL dependence that correlated with protein expression and was confirmed by genetic knockdown. The Bcl-xL inhibitor A1331852 exhibited cytotoxic (EC50, 0.13-1.42 μmol/L) and radiosensitizing activities (sensitizer enhancement ratios, 1.3-1.8). Cytotoxicity was associated with induction of mitochondrial outer membrane permeabilization and caspase-3/7 activation. Efficacy was maintained in a 3-dimensional model in which combination therapy completely eradicated mesothelioma spheroids. Clinical applicability was confirmed by immunohistochemical analysis of Bcl-2 proteins in patient samples and radiosensitizing activity of A1331852 in primary patient-derived mesothelioma cells.

CONCLUSIONS

Mesothelioma cells exhibit addiction to the antiapoptotic protein Bcl-xL, and their intrinsic radioresistance can be overcome by small molecule inhibition of this novel therapeutic target.

The use of real-world evidence to audit normal tissue complication probability models for acute esophageal toxicity in non-small cell lung cancer patients

INTRODUCTION

The aim of this work is to assess the validity of real world data (RWD) derived from an electronic toxicity registration (ETR). As a showcase, the NTCP-models of acute esophageal toxicity (AET) for concurrent chemoradiation (CCRT) for NSCLC patients were used to validate the ETR of AET before/after dose de-escalation to the mediastinal lymph nodes.

MATERIAL AND METHODS

One hundred and one patients received 24 × 2.75 Gy and 116 patients received de-escalated dose of 24 × 2.42 Gy to the mediastinal lymph nodes. The validity and completeness of the ETR was analyzed. The grade ≥2 AET probability was defined according the V50 Gy and V60 Gy NTCP-models from literature. Validity of the models was assessed by calibration and discrimination. Furthermore, sensitivity and specificity for different cut-off points were determined.

RESULTS

The compliance of ETR was 73-80%, with sensitivity and specificity rates of 83% and 86% for grade ≥2 AET, respectively. Discrimination of both NTCP-models demonstrated a moderate accuracy (V50 model, AUC 0.71; V60-model, AUC 0.69). Dose de-escalation did not influence the accuracy of the V50-model; AUC before: 0.69, and AUC after: 0.71. For the V60-model the model-accuracy decreased after dose de-escalation; AUC before: 0.72 and AUC after: 0.62, respectively.

CONCLUSION

RWD is a useful method to audit NTCP models in clinical practice. The NTCP models to predict AET in NSCLC patients showed moderate predictive accuracy. For clinical practice, the V50Gy seems to be most stable for dose de-escalation without compromising safety and efficacy.

Biological Determinants of Chemo-Radiotherapy Response in HPV-Negative Head and Neck Cancer: A Multicentric External Validation

Purpose: Tumor markers that are related to hypoxia, proliferation, DNA damage repair and stem cell-ness, have a prognostic value in advanced stage HNSCC patients when assessed individually. Here we aimed to evaluate and validate this in a multifactorial context and assess interrelation and the combined role of these biological factors in determining chemo-radiotherapy response in HPV-negative advanced HNSCC. Methods: RNA sequencing data of pre-treatment biopsy material from 197 HPV-negative advanced stage HNSCC patients treated with definitive chemoradiotherapy was analyzed. Biological parameter scores were assigned to patient samples using previously generated and described gene expression signatures. Locoregional control rates were used to assess the role of these biological parameters in radiation response and compared to distant metastasis data. Biological factors were ranked according to their clinical impact using bootstrapping methods and multivariate Cox regression analyses that included clinical variables. Multivariate Cox regression analyses comprising all biological variables were used to define their relative role among all factors when combined. Results: Only few biomarker scores correlate with each other, underscoring their independence. The different biological factors do not correlate or cluster, except for the two stem cell markers CD44 and SLC3A2 (r = 0.4, p < 0.001) and acute hypoxia prediction scores which correlated with T-cell infiltration score, CD8⁺ T cell abundance and proliferation scores (r = 0.52, 0.56, and 0.6, respectively with p < 0.001). Locoregional control association analyses revealed that chronic (Hazard Ratio (HR) = 3.9) and acute hypoxia (HR = 1.9), followed by stem cell-ness (CD44/SLC3A2; HR = 2.2/2.3), were the strongest and most robust determinants of radiation response. Furthermore, multivariable analysis, considering other biological and clinical factors, reveal a significant role for EGFR expression (HR = 2.9, p < 0.05) and T-cell infiltration (CD8⁺T-cells: HR = 2.2, p < 0.05; CD8⁺T-cells/Treg: HR = 2.6, p < 0.01) signatures in locoregional control of chemoradiotherapy-treated HNSCC. Conclusion: Tumor acute and chronic hypoxia, stem cell-ness, and CD8⁺ T-cell parameters are relevant and largely independent biological factors that together contribute to locoregional control. The combined analyses illustrate the additive value of multifactorial analyses and support a role for EGFR expression analysis and immune cell markers in addition to previously validated biomarkers. This external validation underscores the relevance of biological factors in determining chemoradiotherapy outcome in HNSCC.

Abstract C009: Clinical pharmacokinetic and pharmacodynamic analyses support biological effectivity of the PARP inhibitor olaparib as radiosensitizer at low doses

Introduction: PARP inhibitors are promising radiosensitizers. Currently identified recommended phase II doses of PARP inhibitors in combination with radiotherapy are 10-fold lower than the EMA and FDA approved dose as single agent. The purpose of this study is to investigate the biologically effective dose range of olaparib for its use as radiosensitizer by assessing pharmacokinetics (PK) and pharmacodynamics (PD). Both the inhibition of pre-treatment PAR levels and the inhibition of radiation induced PARylation therefore have to be determined. Methods: We included PK and PD samples of all NSCLC and breast cancer patients treated at olaparib doses up to 50mg bi-daily (BID) in two phase 1 trials combining radical radiotherapy with olaparib. Plasma samples were collected for PK analysis (ranging from steady state pre-dose olaparib until +12/24 hrs after intake) and peripheral blood mononuclear cells (PBMCs) for PD analysis (pre-treatment, +3 hrs and +12/24 hrs after olaparib intake). Breast cancer patients with the primary tumor in situ had biopsies taken pre-treatment and during olaparib treatment (+3 hrs after intake) before the first fraction of radiotherapy. Olaparib concentrations were determined by HPLC-MS/MS. PAR levels were determined by commercially available ELISA, following both the NCI protocol and REP assay (de Haan et al, 2017) that includes ex vivo irradiation of intact cells to activate PARylation by PARP. PAR levels determined by the REP assay were used to calculate PAR level inhibition during treatment. Results: PK/PD data from blood samples were available from 28 NSCLC patients and 7 breast cancer patients treated with radical radiotherapy and olaparib (17 at 25mg once daily (QD), 14 at 25mg BID and 4 at 50mg BID). Repeat biopsies were available from six out of seven breast cancer patients. The plasma olaparib concentrations increased with the dose levels and showed an expected wide intra-patient variation. In tumors the olaparib concentration varied between 178 and 1441 ng/g with a median tumor to plasma ratio of 0.47. PD analyses demonstrate a significant reduction in PAR levels in PBMCs during olaparib treatment (&gt;95% at +3 hrs after olaparib intake for all dose levels, &gt;90% at +12 hrs in the 25mg BID dose level and 66-99% at +24 hrs in the 25mg QD dose level; all p&lt;0.0001). In pre-treatment samples, ex vivo radiation induced PAR levels by 66-fold (range 23 to 174). This radiation induced PARylation was abolished during olaparib treatment. Compared to corresponding pre-treatment PBMC samples, PAR levels in pre-treatment tumor biopsy samples were higher in all but one patient (median 7-fold higher, range 0.6-60), and increased by only 1.5-fold after ex vivo radiation. Also in tumors, olaparib abolished radiation induced PARylation. PAR levels were reduced by 89% (range 83-99.7%, p&lt;0.0001). Conclusion: Olaparib doses as low as 25mg once and twice daily inhibit PARP activation by irradiation and reduce PAR levels &gt;95% in PBMCs and &gt;83% in tumors, thereby showing biological effectivity. The tumor olaparib concentrations determined in this study were all within a range that has been shown to radiosensitize in preclinical models. Together this supports further development of PARP inhibitors as radiosensitizer at low doses.

Citation Format: Rosemarie de Haan, Dick Pluim, Manon Verwijs, Gabe Sonke, Michel van den Heuvel, Baukelien van Triest, Marcel Verheij, Conchita Vens. Clinical pharmacokinetic and pharmacodynamic analyses support biological effectivity of the PARP inhibitor olaparib as radiosensitizer at low doses [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C009. doi:10.1158/1535-7163.TARG-19-C009

The transformation of radiation oncology using real-time magnetic resonance guidance: A review

Radiation therapy (RT) is an essential component of effective cancer care and is used across nearly all cancer types. The delivery of RT is becoming more precise through rapid advances in both computing and imaging. The direct integration of magnetic resonance imaging (MRI) with linear accelerators represents an exciting development with the potential to dramatically impact cancer research and treatment. These impacts extend beyond improved imaging and dose deposition. Real-time MRI-guided RT is actively transforming the work flows and capabilities of virtually every aspect of RT. It has the opportunity to change entirely the delivery methods and response assessments of numerous malignancies. This review intends to approach the topic of MRI-based RT guidance from a vendor neutral and international perspective. It also aims to provide an introduction to this topic targeted towards oncologists without a speciality focus in RT. Speciality implications, areas for physician education and research opportunities are identified as they are associated with MRI-guided RT. The uniquely disruptive implications of MRI-guided RT are discussed and placed in context. We further aim to describe and outline important future changes to the speciality of radiation oncology that will occur with MRI-guided RT. The impacts on RT caused by MRI guidance include target identification, RT planning, quality assurance, treatment delivery, training, clinical workflow, tumour response assessment and treatment scheduling. In addition, entirely novel research areas that may be enabled by MRI guidance are identified for future investigation.