Friday, September 22, 2023

Prognostic impacts of participation in prospective surgical clinical trials on surgical outcomes in gastric cancer patients – Scientific Reports

Before being weighted with propensity scores, patients who participated in prospective surgical clinical trials had comparable postoperative morbidity and superior overall survival compared to those who did not. After weighting with propensity scores, surgical outcomes, including postoperative morbidity and overall survival, showed no differences between patients enrolled in surgical clinical trials and those who did not.

Even surgeons familiar with prospective surgical clinical trials sometimes feel nervous when performing surgeries on patients registered for clinical trials. In particular, when operating on patients requiring additional procedures for research purposes in addition to standard surgical procedures, surgeons may experience tension and be overwhelmed by unfamiliar procedures. Even when surgical clinical trials are actively conducted, patient safety is of utmost importance. Therefore, whether participation in a prospective surgical clinical trial per se impacts surgical outcomes is a topic that needs to be clarified.

In recent decades, several prospective surgical clinical trials have been conducted worldwide. The Republic of Korea is one of the leading countries in gastric cancer-related surgery and research. Our institution, a major gastric cancer center in Korea, is committed to enrolling patients in several prospective trials. In this study, the number of patients enrolled in surgical clinical trials among all patients undergoing gastric cancer surgery increased over time, reaching nearly 25% (82/250) by 2020. Ten surgical clinical trials were performed during the five years of the study period. Of these, seven were RCTs and the other three were prospective non-randomized surgical trials. The prospective trials required additional procedures besides standard surgery, which may have made the surgeon feel nervous or overwhelmed. As a result, these cases were included in the SCT group.

In the unweighted populations, the proportion of patients who underwent surgical clinical trials in the entire cohort was over 18%. The patients in the SCT group had few known risk factors for postoperative complications. They had a younger age, lower ASA score, higher preoperative hemoglobin and albumin levels, smaller tumor size, and earlier tumor stages19,20,21. This reflects the bias of researchers who recommend surgical clinical trial participation for a relatively healthy and limited number of patients with far advanced gastric cancer. The perioperative outcomes of the SCT group in the unweighted population were similar to those of the non-SCT group, despite having fewer risk factors for postoperative complications. This suggests a possible worsening of perioperative outcomes in the SCT group; however, the two groups had similar outcomes in the weighted population. The overall survival in the SCT group was superior to that in the non-SCT group. However, this superiority may be due to discrepancies in clinicopathological features between the groups, and the task of matching the discrepancies was performed using the PSW method.

RCTs are the best method for analyzing causal relationships, but only a retrospective analysis was possible in this study because it was designed to classify patients according to their participation in prospective studies. Enrolling patients for this study prospectively meant that all patients were allocated to the SCT group. A good alternative for correcting the clinicopathological background of the two groups in a retrospective study was the use of propensity scores. We tried to add as many matching variables as possible to adjust for the two groups evenly and introduced the PSW method to minimize the number of patients who were excluded from the control group.

After PSW, the perioperative outcomes, including each complication type, were comparable between the groups, except for pancreatitis and renal complications. As the incidence of these complications was low, further validation is needed in a study targeting a larger number of patients. The overall survival of the SCT group, which was superior before PSW, was comparable to that of the non-SCT group after PSW. Prospective studies assume that participation in a surgical clinical trial has no significant impact on surgical outcomes, including operation time, intraoperative blood loss, complications, hospital stay, and oncological outcomes. However, to the best of our knowledge, this has not been validated in well-designed studies. This study is expected to encourage patients and surgeons to participate more actively in prospective studies by providing relief to those concerned about adversely affecting the surgical results through participation in a surgical clinical trial.

This study had several limitations. First, since our study was conducted at a single institution, selection bias is possible despite our efforts to reduce it using propensity weighting. Second, long-term recurrence- or relapse-free survival could not be analyzed because of the lack of recurrence-related data. Additional research is needed on adjuvant chemotherapy and recurrence, depending on the participation in clinical trials.

In conclusion, enrolling relatively healthy patients with early tumor lesions was associated with participation in surgical clinical trials. Performing PSW to match the clinicopathological features between the groups, participation in surgical clinical trials did not affect surgical outcomes, including postoperative complications and long-term overall survival. Participation in well-designed surgical clinical trials for medical advancement should be actively encouraged by patients and surgeons without worrying about surgical outcomes.

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