Outcome after surgery depends on both patient-related as well as procedure-related risks. Complications after surgery are a significant burden to patients and to the health system. A vast amount of often unstructured data from different sources are generated during surgery, which contain valuable information associated with outcome. Advances in computer hardware and machine learning now increasingly facilitate the development of prediction models in standardised, parametric, information-rich areas such as the perioperative setting. For the development and validation of risk scores and prediction models, high-fidelity data sources are required to arrive at meaningful and reliable predictions. However, data quality standards in retrospective studies are rarely met. Therefore, the prospective Heidelberg Perioperative Deep Data Registry and Biomaterial Bank (HeiPoDD - Registry and Bio Bank) was started to implement a clinical data base and a corresponding biobank merging the entirety of available clinical records.

The HeiPoDD - Registry and Bio Bank is a study-driven, prospective, single-centre observational registry data base and biomaterial bank. It contains data and material from eligible patients who give informed consent and undergo elective non-cardiac high-risk surgery at the surgical centre of the Heidelberg University Hospital. The screening for eligibility started in January 2022, with no maximum sample size specified in advance. Routine data are recorded and stored during hospital stay and potential readmissions within 90 days after index surgery. The data are merged with the potentially available genome, proteome, flow cytometry, and bio signal data. Endpoints are obtained from routine observations, stored data in the hospital information system and follow-up visits. Further, data and biological specimens from separate perioperative studies with the patients’ consent can be transferred into the HeiPoDD - Registry and Bio Bank as well. This large-scale data collection will allow the calculation of endpoint-specific prediction models using logistic regression models as well as machine learning models. The first 1040 patients included in the HeiPoDD - Registry and Bio Bank are also included in the HeiPoDD study.

The trial protocol and subsequent amendments were approved by the ethics committee of the University of Heidelberg (S-745/2021). Participating patients’ data will be entered only in pseudonymised form. Data and biomaterials will be kept for up to 30 years. The findings will be disseminated in peer-reviewed academic journals.

DRKS00025924, registered on 2021-11-12.

Neoadjuvant (chemo)radiotherapy (n(C)RT) followed by resection with total mesorectal excision (TME) constitutes the standard treatment for patients with locally advanced rectal cancer of the middle and lower third. However, n(C)RT has demonstrated no significant impact on overall survival but is associated with adverse effects, including impaired sphincter and sexual function. We hypothesise that omitting n(C)RT in selected patients with a clear circumferential resection margin (CRM) >1 mm as determined through preoperative MRI is not inferior regarding local recurrence rate within 3 years after surgery. That treatment approach may show fewer adverse effects and be more cost-effective.

Selective neoadjuvant therapy of rectal cancer patients (SELREC) is a randomised controlled, parallel-group, open, multicentre, non-inferiority trial. The experimental intervention involves performing TME surgery without n(C)RT. In contrast, the control intervention adheres to German S3-guidelines, incorporating neoadjuvant radiotherapy (nRT) with a dosage of 5x5 Gy or a total of 50.4 Gy. Additionally, if applicable, concomitant chemotherapy (CT) based on 5-fluorouracil is administered, followed by TME surgery within less than 12 weeks. Adjuvant treatment according to guidelines is allowed depending on the (y)pTNM stage.

The inclusion criteria for this study encompass adult patients with primary adenocarcinoma of the rectum in whom the main tumour mass is located less than 12 cm away from the anal verge, as assessed via proctoscopy. Additionally, eligible participants are required to have a preoperative tumour stage determined by MRI of either T1 or T2 with lymph node involvement (N1) or T3 with no lymph node involvement (N0) or with lymph node involvement (N1) and no distant metastases (M0). The assessment of a clear CRM >1 mm, based on MRI, is another prerequisite for inclusion. A total of 1074 patients in approximately 35 centres are planned to be allocated to the trial.

The primary endpoint of the trial is local recurrence within 3 years after surgery. The primary estimand is based on the full analysis set using a logistic mixed model (margin 3%). The first secondary endpoint is no/minor low anterior resection syndrome (LARS) score at 2 years after surgery, and further secondary endpoints include survival outcomes and quality of life. Safety analysis involves describing the frequencies of major intervention-specific complications, such as the acute toxicity of n(C)RT according to CTCAE and perioperative morbidity and mortality according to Clavien-Dindo criteria.

SELREC is financially supported by the German Federal Ministry of Education and Research.

This trial has been prospectively registered in the German Clinical Trials Register.

Previously, the study had been approved by the responsible ethics committee of Heidelberg and the local ethics committees of the collaborating institutions before patient enrolment. Any protocol deviation that has an impact on relevant parameters such as study design, endpoints or patient safety will be reported to the responsible ethics committees.

The results will be published in a peer-reviewed scientific journal and on institutional websites.

German Clinical Trials Register DRKS00030567.