Radiotherapy is an important treatment for many malignant tumors. However, radioresistance remains a major cause of treatment failure, often leading to tumor recurrence or progression. As a key factor affecting prognosis, radioresistance currently lacks reliable methods for identifying high-risk individuals before treatment. Liquid biopsy, as a non-invasive and dynamic monitoring tool, offers unique advantages for real-time assessment. Previous studies from our group have shown that peripheral blood levels of CHI3L1 are significantly elevated in patients with radioresistant tumors and may serve as a predictive biomarker for radiotherapy sensitivity. This study aims to conduct a multicenter, bidirectional cohort study to systematically evaluate the predictive value of peripheral blood CHI3L1 as a pan-cancer biomarker for tumor response to radiotherapy.

Inclusion Criteria:

• Voluntarily signed informed consent form;
• Age ≥ 18 years;
• No restrictions on sex;
• Histologically confirmed diagnosis of one of the following malignant tumors: nasopharyngeal carcinoma, head and neck cancer, lung cancer, breast cancer, gastric cancer, colorectal cancer, glioma, esophageal cancer, liver cancer, cholangiocarcinoma, cervical cancer, prostate cancer, or bladder cancer;
• Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1.

Exclusion Criteria:

• Patients with any serious comorbidities that may pose an unacceptable risk or adversely affect compliance with the study protocol. Examples include unstable heart disease requiring treatment, chronic hepatitis, renal disease with poor clinical status, uncontrolled diabetes mellitus (fasting blood glucose > 1.5 × ULN), or psychiatric disorders.
• Deemed unsuitable for participation in the study at the discretion of the investigators.

Patients with tumors who require radiotherapy