CT Imaging and Clinical Features to Predict Outcomes in Patients With Gastric Cancer

This is a single-center, non-interventional prospective observational cohort study designed to validate a prognostic prediction model for gastric cancer that integrates pretreatment CT imaging features with clinical variables. The model was developed from a previous retrospective cohort of patients with gastric cancer using pretreatment CT images, clinicopathological information, treatment data, and survival outcomes.

Adults with newly diagnosed gastric cancer who are scheduled to receive surgery, chemotherapy, immunotherapy, or combined treatment at the study center will be prospectively enrolled. During routine clinical care, researchers will collect pretreatment CT images and relevant demographic, clinicopathological, laboratory, tumor marker, treatment, and follow-up data. Quantitative CT features related to tumor morphology, density, texture, and spatial heterogeneity will be integrated with clinical variables such as age, sex, TNM stage, Lauren classification, serum tumor markers, and treatment modality to generate individualized prognostic risk estimates.

Model predictions will be compared with observed clinical outcomes during follow-up to evaluate prognostic performance and risk stratification. Model performance will also be assessed in clinically relevant subgroups, including groups defined by treatment modality, clinical stage, age, and sex. Statistical analyses will include Kaplan-Meier survival analysis, log-rank tests, and Cox proportional hazards regression with adjustment for potential confounding factors.

This study will not assign treatment or alter routine clinical care. All treatment decisions will be made by treating clinicians according to each participant's clinical condition and current clinical practice. Model-generated predictions will be stored for research purposes only and will not be provided to clinicians for treatment decision-making. Clinical and imaging data will be coded and de-identified and stored in a password-protected research database. Data quality will be supported by standardized data collection procedures, investigator training, independent data checking, imaging quality review, and standardized follow-up procedures.

• No intervention (observational study) (Other): No intervention or treatment will be assigned by the study protocol. All diagnostic and treatment decisions, including surgery, chemotherapy, immunotherapy, or combined treatment, will be made by treating clinicians as part of routine clinical care. The predefined CT radiomics-based prognostic model will be applied to collected imaging and clinical data for research validation only. Model-generated predictions will not be used to guide or modify clinical treatment decisions.

Primary outcomes

• Overall Survival (OS) [From initiation of treatment until death or last follow-up, assessed up to 12 months]: Overall survival is defined as the time from initiation of initial treatment to death from any cause. Participants who are alive at the last available clinical follow-up will be censored at the date of last follow-up. Survival status will be obtained from medical records, telephone follow-up, and death certificates.

Secondary outcomes

• Progression-Free Survival (PFS) [From initiation of treatment until disease progression, death, or last follow-up, assessed up to 12 months]: Progression-free survival is defined as the time from initiation of treatment to the first documented disease progression or death from any cause, whichever occurs first. Participants without disease progression or death will be censored at the date of the last available clinical assessment.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Histologically or pathologically confirmed gastric cancer and receiving treatment at the study center.
* Age ≥18 years.
* Complete pretreatment CT imaging data available from the study center.

Exclusion Criteria:

* Pretreatment CT images of insufficient quality for analysis.
* Incomplete clinical data.
* Presence of another malignant tumor in addition to gastric cancer.