Biomarkers in gastric cancer. Studies on immunological and metabolic aspects

Gastric cancer is one of the leading causes of cancer-related mortality worldwide. The prognosis is often poor, and treatment remains challenging. Currently, prognosis is primarily assessed based on the anatomical spread of the tumor, but this is not always sufficient to predict individual disease progression or response to therapy. Therefore, new prognostic factors are needed to assist in patient risk assessment and to improve postoperative care.

This dissertation was conducted as a retrospective cohort study, utilizing data from 571 gastric cancer patients who underwent surgery at Oulu University Hospital between 1983 and 2016. The study employed immunohistochemical staining methods on tissue samples to investigate factors related to cellular metabolism and the innate immune system. The results demonstrated that Toll-like receptors TLR2, TLR3, and TLR6, which belong to the body's innate defense system, are associated with the prognosis of gastric cancer patients and may serve as useful biomarkers for prognostic evaluation. Conversely, cellular metabolism factors such as monocarboxylate transporters MCT1 and MCT4, as well as mitochondrial cytochrome c oxidase 1 (MTCO1), did not prove to be independent prognostic factors in this study, though the findings do deepen the understanding of the metabolic background of the disease.

It is currently known that gastric cancer can be divided into molecular subtypes with distinct clinical outcomes and treatment responses. However, identifying these subtypes has traditionally required expensive and time-consuming gene sequencing. This research investigated whether these molecular subtypes could be identified using routine immunohistochemical methods and in situ hybridization. The results indicate that gastric cancer can be classified into prognostically significant subgroups using standard staining methods already in routine clinical use.

These findings increase the understanding of the metabolic and immunological regulation of gastric cancer. The study also provides new support for the further investigation of these biomarkers and may help identify potential new therapeutic targets. Classifying gastric cancer into molecular subtypes upon diagnosis allows for personalized therapeutic interventions and enhanced prognostic accuracy.