J. W. van Sandick’s research while affiliated with Netherlands Cancer Institute and other places

Background Potentially curative therapy for locally advanced gastric cancer consists of gastrectomy, usually in combination with perioperative chemotherapy. An oncological resection includes a radical (R0) gastrectomy and modified D2 lymphadenectomy; generally, a total omentectomy is also performed, to ensure the removal of possible microscopic disease. However, the omentum functions as a regulator of regional immune responses to prevent infections and prevents adhesions which could lead to bowel obstructions. Evidence supporting a survival benefit of routine complete omentectomy during gastrectomy is lacking. Methods OMEGA is a randomized controlled, open, parallel, non-inferiority, multicenter trial. Eligible patients are operable (ASA < 4) and have resectable (≦ cT4aN3bM0) primary gastric cancer. Patients will be 1:1 randomized between (sub)total gastrectomy with omentum preservation distal of the gastroepiploic vessels versus complete omentectomy. For a power of 80%, the target sample size is 654 patients. The primary objective is to investigate whether omentum preservation in gastrectomy for cancer is non-inferior to complete omentectomy in terms of 3-year overall survival. Secondary endpoints include intra- and postoperative outcomes, such as blood loss, operative time, hospital stay, readmission rate, quality of life, disease-free survival, and cost-effectiveness. Discussion The OMEGA trial investigates if omentum preservation during gastrectomy for gastric cancer is non-inferior to complete omentectomy in terms of 3-year overall survival, with non-inferiority being determined based on results from both the intention-to-treat and the per-protocol analyses. The OMEGA trial will elucidate whether routine complete omentectomy could be omitted, potentially reducing overtreatment. Trial registration ClinicalTrials.gov NCT05180864. Registered on 6th January 2022.

The genome of esophageal adenocarcinoma (EAC) is highly unstable and might evolve over time. Here, we track karyotype evolution in EACs in response to treatment and upon recurrence through multi-region and longitudinal analysis. To this end, we introduce L-PAC, a bio-informatics technique that allows inference of absolute copy number aberrations (CNA) of low-purity samples by leveraging information of high-purity samples from the same cancer. Quantitative analysis of matched absolute CNAs reveals that the amount of karyotype evolution induced by chemoradiotherapy (CRT) is predictive for early recurrence and depends on the initial level of karyotype intra-tumor heterogeneity. We observe that CNAs acquired in response to CRT are partially reversed back to the initial state upon recurrence. CRT hence alters the fitness landscape to which tumors can adjust by adapting their karyotype. Together, our results indicate that karyotype plasticity contributes to therapy resistance of EACs.

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.

Background The COVID-19 pandemic caused disruption of regular healthcare leading to reduced hospital attendances, repurposing of surgical facilities, and cancellation of cancer screening programmes. This study aimed to determine the impact of COVID-19 on surgical care in the Netherlands. Methods A nationwide study was conducted in collaboration with the Dutch Institute for Clinical Auditing. Eight surgical audits were expanded with items regarding alterations in scheduling and treatment plans. Data on procedures performed in 2020 were compared with those from a historical cohort (2018–2019). Endpoints included total numbers of procedures performed and altered treatment plans. Secondary endpoints included complication, readmission, and mortality rates. Results Some 12 154 procedures were performed in participating hospitals in 2020, representing a decrease of 13.6 per cent compared with 2018–2019. The largest reduction (29.2 per cent) was for non-cancer procedures during the first COVID-19 wave. Surgical treatment was postponed for 9.6 per cent of patients. Alterations in surgical treatment plans were observed in 1.7 per cent. Time from diagnosis to surgery decreased (to 28 days in 2020, from 34 days in 2019 and 36 days in 2018; P < 0.001). For cancer-related procedures, duration of hospital stay decreased (5 versus 6 days; P < 0.001). Audit-specific complications, readmission, and mortality rates were unchanged, but ICU admissions decreased (16.5 versus 16.8 per cent; P < 0.001). Conclusion The reduction in the number of surgical operations was greatest for those without cancer. Where surgery was undertaken, it appeared to be delivered safely, with similar complication and mortality rates, fewer admissions to ICU, and a shorter hospital stay.

Background Oesophageal gastrointestinal stromal tumours (GISTs) account for ≤1% of all GISTs. Consequently, evidence to guide clinical decision-making is limited. Methods Clinicopathological features and outcomes in patients with primary oesophageal GIST from seven European countries were collected retrospectively. Results Eighty-three patients were identified, and median follow up was 55.0 months. At diagnosis, 59.0% had localized disease, 25.3% locally advanced and 13.3% synchronous metastasis. A biopsy (Fine Needle aspiration n = 29, histological biopsy n = 31) was performed in 60 (72.3%) patients. The mitotic count was low (<5 mitoses/50 High Power Fields (HPF)) in 24 patients and high (≥5 mitoses/50 HPF) in 27 patients. Fifty-one (61.4%) patients underwent surgical or endoscopic resection. The most common reasons to not perform an immediate resection (n = 31) were; unresectable or metastasized GIST, performance status/comorbidity, patient refusal or ongoing neo-adjuvant therapy. The type of resections were enucleation (n = 11), segmental resection (n = 6) and oesophagectomy with gastric conduit reconstruction (n = 33), with median tumour size of 3.3 cm, 4.5 cm and 7.7 cm, respectively. . In patients treated with enucleation 18.2% developed recurrent disease. The recurrence rate in patients treated with segmental resection was 16.7% and in patients undergoing oesophagectomy with gastric conduit reconstruction 36.4% . Larger tumours (≥4.0 cm) and high (>5/5hpf) mitotic count were associated with worse disease free survival. Conclusion Based on the current study enucleation can be recommended for oesophageal GIST smaller than 4 cm, while oesophagectomy should be preserved for larger tumours. Patients with larger tumours (>4 cm) and/or high mitotic count should be treated with adjuvant therapy.

Background The PERISCOPE I study was designed to assess the safety and feasibility of (sub)total gastrectomy, cytoreductive surgery (CRS), and hyperthermic intraperitoneal chemotherapy (HIPEC) with oxaliplatin and docetaxel for gastric cancer patients who have limited peritoneal dissemination. The current analysis investigated changes in perioperative management together with their impact on postoperative outcomes.Methods Patients with resectable gastric cancer and limited peritoneal dissemination were administered (sub)total gastrectomy, CRS, and HIPEC with oxaliplatin (460 mg/m2) and docetaxel (escalating scheme: 0, 50, 75 mg/m2). Of the 25 patients who completed the study protocol, 14 were treated in the dose-escalation cohort and 11 were treated in the expansion cohort (to optimize perioperative management).ResultsA significant proportion of the patients in the dose-escalation cohort (n = 7, 50%) had ileus-related complications. In this cohort, enteral nutrition was started immediately after surgery at 20 ml/h, which was increased on day 1 to meet nutritional needs. In the expansion cohort, enteral nutrition was administered at 10 ml/h until day 3, then restricted to 20 ml/h until day 6, supplemented with total parenteral nutrition to meet nutritional needs. Ileus-related complications occurred for two patients (18%) of the expansion cohort. The intensive care unit (ICU) readmission rate decreased from 50 (n = 7) to 9% (n = 1; p = 0.04).Conclusion The implementation of a strict nutritional protocol during the PERISCOPE I study was associated with a decrease in postoperative complications. Based on these results, a perioperative care path was described for the gastric cancer HIPEC patients in the PERISCOPE II study.

Introduction The Lauren classification of gastric adenocarcinoma describes three histological subtypes, the intestinal, the diffuse and the mixed type carcinoma. The metastatic pattern of gastric adenocarcinoma by histological subtype has not been studied. Methods Gastric adenocarcinoma patients with metastatic disease at the time of diagnosis between 1999 and 2017 were identified through the Netherlands Cancer Registry. The Lauren classification was determined based on pathology reports archived in the Dutch Pathology Registry and was linked to individual cases in the Netherlands Cancer Registry. Results Among 8 231 newly diagnosed, metastatic and evaluable gastric adenocarcinoma patients, 57 % had an intestinal type carcinoma, 38 % patients had a diffuse type carcinoma and 5 % had a mixed type carcinoma. Intestinal type carcinomas more often metastasized to the liver (57 % versus 21 %, p < 0.0001) and lungs (13 % versus 7 %, p < 0.0001), whereas diffuse type carcinomas more often metastasized to the peritoneum (58 % versus 29 %, p < 0.0001) and bones (9 % versus 6 %, p < 0.0001). Patients with a diffuse type carcinoma had a worse survival perspective regardless of the number or the location of the metastases. Conclusion In this national cohort study, metastatic gastric adenocarcinoma of the intestinal type had a predilection for the liver and that of the diffuse type for the peritoneum.

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).

Prolonged length of hospital stay is a negative outcome of esophageal cancer surgery, not only for the patient; it also leads to increased hospital costs. Within the scope of value-based health care, this study aimed to analyze Dutch hospital performance in terms of length of hospital stay and to investigate its association with readmission rates. Since both parameters are influenced by the occurrence of complications, this study only included patients after an uncomplicated esophagectomy. Methods All patients registered in the Dutch Upper GI Cancer Audit (DUCA) who underwent a potentially curative esophageal cancer resection between 2015 and 2018 were considered for inclusion. Patients were excluded if they had an intraoperative and/or postoperative complication, if they were retransferred to the intensive care unit, or if they had undergone a re-intervention. Length of hospital stay was dichotomized around the national median into “short admissions” and “long admissions”. Hospital variation was evaluated using a case-mix corrected funnel plot based on multivariable logistic regression analyses. Association of length of hospital stay with readmission rates was investigated using the χ2-statistic. Results A total of 1,007 patients was included for analyses. National median length of hospital stay was 9 days, ranging from 6.5–12.5 days among 17 hospitals. The percentage of “short admissions” per hospital ranged from 7.7% to 93.5%. After correction for case-mix variables, 2 hospitals had significantly higher “short admission” rates and 4 hospitals had significantly lower “short admission” rates (figure 1). Overall, 6.2% (hospital variation [0.0%–13.2%]) of patients was readmitted. Hospital readmission rates were not significantly different between hospitals with a short length of hospital stay and those with a long length of hospital stay (5.5% versus 7.6%; p = 0.19). Conclusion Based on these nationwide audit data, length of hospital stay after an uncomplicated esophagectomy varied significantly between hospitals and ranged from 6.5 to 12.5 days among Dutch hospitals. Short length of hospital stay was not associated with a higher readmission rate. The hospital variation indicates that enhanced recovery programs are not implemented at the same level of efficacy among hospitals in the Netherlands. Nationwide improvement might lead to a substantial reduction of hospital costs.