Omentectomy versus omentum preservation in the treatment of locally advanced gastric cancer (OMENTAL TRIAL): study protocol for a multicenter randomized controlled trial

In the landscape of human anatomy, the stomach is often viewed as a solitary organ, but it is surrounded by a vast, fatty apron known as the omentum. This tissue, which hangs down from the stomach and drapes over the intestines, has long been a subject of debate among surgeons treating advanced stomach cancer. For decades, the standard approach to curing this disease has involved removing the stomach along with a wide margin of surrounding tissue, including the entire omentum. The logic was rooted in a desire to be thorough: surgeons believed this fatty apron might hide microscopic cancer cells that had escaped the main tumor, and removing it was seen as a necessary step to prevent the cancer from returning. However, this aggressive removal comes with a cost. The omentum is not just a passive layer of fat; it acts as a natural barrier against infection and helps the body heal after surgery. Cutting it away can lead to longer operations, more blood loss, and a higher risk of complications for the patient.

The question facing the medical community has become whether this traditional, all-or-nothing approach is truly necessary. If the omentum is left intact, does the cancer come back more often? Or is the standard practice of removing it an unnecessary risk that harms patients without providing a real benefit? This uncertainty has persisted because most previous studies were retrospective, meaning they looked back at past records rather than testing a specific plan in real time. Furthermore, much of the existing data comes from Asian countries where cancer screening and treatment protocols differ significantly from those in the West. To answer this question with certainty, a new, large-scale experiment was needed to see if preserving this tissue could be just as safe as removing it, while offering a gentler path to recovery.

This is the mission of the OMENTAL trial, a major medical study currently underway across multiple hospitals in Spain. The researchers are conducting a prospective, randomized controlled trial, which is considered the gold standard for medical evidence. In this study, patients diagnosed with locally advanced stomach cancer who are candidates for surgery and chemotherapy are randomly assigned to one of two groups. One group undergoes the traditional procedure where the surgeon removes the entire omentum along with the stomach. The other group undergoes a modified surgery where the surgeon carefully preserves the omentum, cutting the connection to the stomach but leaving the main body of the fatty tissue in place. While the study design is described as blinded regarding the patient and the investigator analyzing the data, the operating surgeon must necessarily know which procedure is being performed to execute the specific surgical technique.

The primary goal of the OMENTAL trial is to determine if preserving the omentum is non-inferior to removing it. In plain terms, the researchers want to prove that keeping the tissue does not lead to worse survival rates or a higher chance of the cancer returning. The main measure of success is disease-free survival, which tracks how long a patient lives without the cancer coming back. If the study finds that patients with the preserved omentum do just as well as those who had it removed, it would suggest that the routine removal of this tissue is not required. The secondary goals include tracking how many patients experience complications after surgery, how quickly they recover, and their overall survival rates. The researchers also plan to look at specific details like the type of surgery performed, the patient's age, and the specific stage of the cancer to ensure the results hold true across different types of patients.

The study involves a carefully selected group of adults over the age of eighteen who have a specific type of stomach cancer that has spread beyond the inner lining but has not yet spread to distant organs. These patients must be healthy enough to undergo chemotherapy before and after their surgery. The trial aims to recruit 474 patients from various hospitals across Spain, a number calculated to provide a statistically reliable answer. Recruitment began in July 2023 and is expected to continue for about four years, with the final results analyzed five years after the last patient is enrolled. Throughout this time, patients will be followed closely, with check-ups scheduled every few months to monitor for any signs of recurrence or new health issues.

The implications of this research are significant for the future of cancer care in Europe and beyond. If the trial confirms that preserving the omentum is safe, it could fundamentally change the standard of care for stomach cancer surgery. Instead of a routine, aggressive removal of tissue that might not be needed, surgeons could adopt a more conservative approach that spares the patient from unnecessary trauma and potential complications. This would represent a shift toward treatments that are not only effective at curing the disease but also kinder to the patient's body during the recovery process. Until the data is collected and analyzed, however, the traditional method remains the standard, and the medical community waits to see if this large, rigorous experiment can finally settle the debate. The OMENTAL trial stands as a testament to the ongoing effort to refine medical practices, ensuring that every step taken in the operating room is truly necessary for the patient's well-being.