Discussion
tumor, LAGC, tumours, tumour, gastric cancer
TUMOR, METASTASIS, MALIGNANT NEOPLASM, TUMOURS, TUMOUR, REGRESSION, PATHOGENESIS, GASTRIC CANCER
Worldwide, gastric cancer is one of the most malignant neoplasms and has a high mortality rate. In recent years, with the acceleration of the ageing population and longer life expectancy, the incidence and absolute number of cases of gastric cancer in the elderly has been increasing, and 80% of these patients have LAGC. However, information regarding elderly patients with LAGC is very limited. From a pathogenesis point of view, advanced gastric cancer and early gastric cancer have very different biological and molecular characteristics [To date, the tumor node metastasis (TNM) staging system is considered to be the ‘gold standard’ for prognostication in oncology [In this study, after using multivariable Cox regression analysis and statistical modelling, it was found that the TNM staging system, demographic variables (age and race), clinicopathological variables (tumour size and differentiation) and surgery-related factors (gastrectomy type, LNR and chemoradiotherapy therapy) were independent risk factors for OS and overall CSS in elderly patients with LAGC. Older age and Indian ethnic backgrounds were associated with poor OS and CSS. The unfavourable prognosis of elderly patients may be explained by poor surgical tolerance and the inability to complete perioperative chemotherapy. Our study also found that Asian-American and Asian populations have the best prognosis for gastric cancer, which was consistent with the reports of some previous studies [The degree of differentiation of the tumour is an important index for assessing prognosis and malignant potential, reflecting the biological behaviour of the tumour itself. Even in some tumours, tumour differentiation as an important biologic factor has been incorporated into the staging system [After verifying the discrimination and calibration of the nomograms, it is necessary to further estimate the clinical usefulness of the model. This research introduced decision curve analysis (DCA) to evaluate the clinical usefulness of the nomogram on the basis of the net benefit (defined as the proportion of true positives minus the proportion of false-positives, weighted by the relative harm of a false-positive and false-negative result). DCA was developed as a method to determine whether the use of a prediction model in the clinic to determine if decision-making would do more good than harm. At the same time, unlike traditional biostatistical methods, which only evaluate the accuracy of a model, DCA could tell us whether using a model to aid clinical decision-making would improve outcomes for our patients. By evaluating the net benefit of nomogram-assisted decisions at different threshold probabilities, decision curve analysis visually indicated that the nomogram conferred a high clinical net benefit and might better guide clinical decision-making.In this study, we found that the factors affecting patient OS and CSS were consistent, reflecting that advanced gastric cancer has an important impact on the survival of elderly patients. Identifying and evaluating risk factors with substantial predictive prognostic value is of great clinical importance in elderly patients with LAGC. Moreover, we can also see that the patients in the external validation set have significantly better CSS and OS than the patients from the SEER database. Apart from racial and age differences, another reason may be that all patients received standardized perioperative care based on the standardized Enhanced Recovery After Surgery (ERAS) protocol among the three externally verified centres. Over the past two years, ERAS has developed appreciably and has become an important part of the perioperative treatment of gastric cancer [