This study is an observational research.

1. The study first conducted an electronic questionnaire survey among clinicians working in general and specialized hospitals at various levels nationwide to understand the implementation status and influencing factors of comprehensive geriatric assessment (CGA) for elderly cancer patients in China.
2. Based on the survey results, an interview outline was developed, and semi-structured interviews were conducted with professional doctors experienced in the diagnosis and treatment of elderly cancer patients to further explore the comprehensive factors influencing the implementation of CGA for this population.
3. According to the feedback from the semi-structured interviews, the survey results, and literature reports, the assessment dimensions required for the CGA screening tool were selected. An expert consultation survey questionnaire was designed around these dimensions, and the most suitable assessment items under each dimension were determined using the Delphi expert consultation method.
4. The G8 scale was used to assess elderly cancer patients. Items were selected based on their performance to form the screening tool. By setting thresholds and allocating weights for each item, CGA Screening Tool 1.0 was developed.
5. Pre-testing and modification of the screening tool were conducted. Investigators used the initially formed screening tool to conduct one-on-one patient testing. Feedback on the tool's clarity, relevance, clinical applicability (localization), and feasibility was obtained through consultation with a clinical expert panel to improve and refine its content and management process. This led to the revision and formation of CGA Screening Tool 2.0.
6. The reliability and validity of the CGA screening tool were verified using classical measurement theory to ensure the stability, reliability, and effectiveness of the scale tool in practical applications.
7. Patients were assessed using both CGA and the screening tool. External validation of Screening Tool 2.0 was performed using CGA as the gold standard to further evaluate the sensitivity, specificity, and accuracy of the screening tool.
8. Patients who participated in the assessment during the study were followed up to compare the correlation between different assessment results and patient completion of anti-tumor treatment, treatment efficacy, and the risk of related adverse reactions. The impact of the CGA screening tool on the implementation of CGA and its predictive ability for anti-tumor treatment were explored. Study data were obtained from the electronic medical record database and hospital information system of Sichuan Cancer Hospital, including clinicopathological features such as gender, age, clinical stage at diagnosis, and information related to anti-tumor treatment.

Inclusion Criteria:

1. Age ≥ 65 years old
2. There are clear pathological data to diagnose malignant tumors, and follow-up anti-tumor therapy is determined in this institution
3. Have a certain enthusiasm for this study, and voluntarily participate in this study

Exclusion Criteria:

1. Unable to understand the content of the research
2. Unable to cooperate with CGA and screening assessments

Among all participants, 316 were used to develop the screening tool, 10 for the pre-testing, and 132 for the reliability and validity testing of the screening scale. After the scale was completed, the remaining 220 patients were used for the external validation of the tool. Finally, all patients evaluated using the screening tool were grouped according to different screening results, and the treatment effects and risks among the groups were compared.