Optimal Staging and Surgical Treatment for Gastric Cancer

Abstract

Gastric cancer is the fifth most frequently diagnosed cancer and the third leading cause of cancer-related mortality worldwide, accounting for over one million new cases and approximately 768.000 deaths in 2020. Of the 1200 newly diagnosed patients every year in the Netherlands, only some 500 patients undergo curative treatment. Most patients are not eligible for curative treatment due to advanced tumor stage (including distant metastases) detected at diagnosis, and its prognosis mainly depends on this stage. To distinguish between curative and non-curative disease, preoperative staging is of great importance. Regardless of much research being done in the field of gastric cancer, some knowledge gaps remain. For example, it remains challenging to identify the best staging options and perioperative therapy, to determine the most beneficial surgical approach to reduce the number of complications, and to determine treatment in the case of metastatic disease. Although FDG-PET/CT and SL have increasingly been implemented in the Netherlands after revision of the guidelines in 2016, this thesis demonstrates that the additive value of FDG-PET/CT in the staging process is only limited, and its use will almost certainly not be cost-effective in the Netherlands, due to the low detection rate of distant metastases and relatively high detection rate of secondary findings requiring additional examinations. Based on the results of the current thesis, it is advised that FDG-PET/CT will no longer be performed as standard of care in all patients with locally advanced gastric adenocarcinoma, and the Dutch national guidelines for patients with gastric cancer will likely be amended. Also, this thesis concluded that staging laparoscopy detects peritoneal disease or non-resectable tumors with ingrowth in other organs in 1 out of 5 patients. These numbers emphasize that laparoscopy is a good staging tool that adds considerably to the staging process of patients with gastric cancer, and likely will be a game changer for patients in whom metastatic disease is detected. Regarding surgical treatment, the current research demonstrates the following: surgeons favor a minimally invasive surgical approach over an open approach; benefits of minimally invasive gastrectomy during its early introduction were demonstrated for distal gastrectomy but not for total gastrectomy as a significant higher risk of anastomotic leakage was found; anastomotic leakage and pulmonary complications are the major attributors to deteriorated clinical outcomes after gastrectomy; for gastric and GEJ diffuse type cancer, including signet ring cell carcinomas, the use of perioperative chemotherapy plus surgery is associated with better outcomes and lower overall mortality compared to surgery alone; of patients with potentially curable gastric cancer, 33% does not undergo a resection, mostly due to patient refusal or comorbidity; and finally, non-curative gastrectomy does not lead to additional postoperative risks compared to curative gastrectomy in patients with similar characteristics and may be considered in fit patients with advanced gastric cancer. In conclusion, the research presented in this thesis aimed to improve the preoperative staging process and evaluated several aspects of the surgical treatment of gastric cancer. Optimizing staging will allow for a more tailored treatment for these patients.