Gastric cancer is the fifth cause of cancer-related mortality worldwide. Gastric carcinogenesis involves the progression from premalignant conditions such as atrophic gastritis and intestinal metaplasia to premalignant lesions like dysplasia, and ultimately carcinoma. Most diagnoses of gastric cancer are made at advanced stages, with a five-year relative survival rate of 36%. Therefore, early detection of premalignant conditions and lesions is crucial, as it allows for timely surveillance and treatment, which can improve patient survival.

Upper gastrointestinal endoscopy (UGE) is the first-line examination for diagnosing upper gastrointestinal tract pathology, particularly oncological conditions. The European Society of Gastrointestinal Endoscopy (ESGE) and the United European Gastroenterology (UEG) have established that UGE quality is a priority, identifying specific quality parameters, such as the duration of the procedure, which is the most extensively studied parameter.

According to ESGE recommendations, all UGE reports should include the procedure time (goal: ≥90% of reports), which should be seven minutes or longer for surveillance of intestinal metaplasia. This time threshold follows a study that established a causal relationship between longer procedures (≥ seven minutes) and a higher detection rate of premalignant gastric conditions and lesions. Subsequent observational studies have generally shown that setting a minimum procedure time increases the detection rate of lesions.

The definition of procedure time varies between studies, being described as the time from intubation to extubation, but also as the time for withdrawing the endoscope from the second portion of the duodenum (D2) to extubation, also known as withdrawal time.

The hypothesis under study is that a better definition of the most appropriate time for a diagnostic UGE could standardize reports, improve malignant lesion detection rates, and reduce the rate of undiagnosed cancers, without any additional risk to patients.

Existing studies have been retrospective or comparative between different temporal cohorts, with no prospective or randomised comparative studies, nor any studies comparing the two existing metrics. Therefore, the aim of this study is to evaluate the best metric for inspection time during a diagnostic and/or surveillance UGE, between total inspection time versus withdrawal time, for the identification of malignant lesions.

Execution of UGE using high-resolution endoscopes, with the option of virtual chromoendoscopy, according with the physician's preference. Possible optimization of visualization with washing and/or the use of simethicone or similar, as pre-medication or during the examination, according with the physician's preference. Patients will be randomised to one of the following measurements-total time versus withdrawal time-in a parallel 1:1 scheme. The allocation of the randomisation group will be computer-generated. The endoscopist must record the time at which the following three anatomical structures are reached (either by noting during the procedure or based on the information in the photographic documentation), before any biopsies or therapeutic interventions, in the format xxh:xxmin:xxsec:

1. First esophageal image;
2. First image of the second portion of the duodenum;
3. Last esophageal image.

The endoscopist will perform the UGE for as long as clinically necessary, which may be shortened if there is any need to interrupt the procedure for any clinical reason (such as intolerance or other), without any minimum or maximum time limits.

Although this is a non-interventional study that does not involve any modification to daily clinical practice, regarding the analyzed UGE, the study will be submitted for evaluation by the Ethics Committee of the Portuguese Institute of Oncology of Coimbra and will be performed in accordance with the principles of the Helsinki Declaration. All analyzed data will be kept confidential, and the investigators will ensure the anonymity of the patients included during data analysis and publication.

This study aims to define the best metric for quantifying the most appropriate time for performing a diagnostic or surveillance UGE. To our knowledge, all existing studies on the topic of procedure time in UGE are observational. This study will be the first randomised clinical trial in this area, with the purpose of providing a systematic evaluation that will contribute to the optimization of quality measures.

Inclusion Criteria:

• Age ≥ 18 years
• Diagnostic or surveillance upper gastrointestinal endoscopy for premalignant conditions
• Informed consent for the execution of the upper gastrointestinal endoscopy and participation in the study

Exclusion Criteria:

• Previous esophagus, stomach, or duodenum surgery
• Known or suspected neoplasia
• Therapeutic procedure (polypectomy, argon plasma coagulation, hemostasis, others)