Towards an improved survival in gastric cancer

Abstract

Gastric cancer is a globally important contributor to morbidity and mortality from cancer. The age-standardised incidence has declined during the last decades, but the total incidence has not due to an aging population. Despite advancements in treatment strategies, where surgery with gastrectomy is a key factor, survival remains poor. With the overarching aim to help improve the long-term survival in gastric cancer, this thesis included four Swedish population-based cohort studies that assessed survival trends, prognostic factors, annual surgeon and hospital volume of gastrectomies, and proficiency gain of surgeons starting to conduct gastrectomies.

Paper I used data from national Swedish registries for cancer, patients and mortality to examine trends in incidence and survival for gastric cancer between 1990 and 2017. For gastric non-cardia cancer, incidence decreased while survival remained unchanged. For gastric cardia cancer, incidence slightly increased and survival improved. For the decreasing proportion who underwent gastrectomy, survival increased, especially for those with gastric cardia cancer.

Paper II included patients operated for gastric cancer in Sweden between 2006 and 2015 with follow-up until 2019. The study described a new cohort of 2154 patients who had undergone surgery for gastric cancer, corresponding to 98% of all cases in Sweden. It also examined factors influencing long-term survival after surgery, and found that tumour stage, comorbidities and age were prognostic factors, whereas sex, tumour sub-localisation and education were not.

Paper III included patients operated for gastric cancer in Sweden between 2006 and 2015 with follow-up until 2020. The study examined surgeons’ and hospitals’ annual volume of gastrectomies in relation to long-term survival in patients operated for gastric cancer. Neither the surgeons’ nor the hospitals’ annual volume of gastrectomies influenced the long-term survival.

Paper IV examined patients who underwent gastrectomy for gastric cancer in Sweden between 2006 and 2015 with follow-up until 2020. The study examined proficiency gain for individual surgeons from when they started conducting gastrectomies within the study period. The study revealed a learning phase up till the twentieth surgical case, with worse long-term survival before case number 20 compared to after.