Background Thymic carcinoma (TC) is a rare and aggressive mediastinal malignancy with poor prognosis. Our study aimed to develop a nomogram to predict overall survival (OS) of TC patients.

Method A total of 156 patients confirmed TC between 1996 and 2023 were selected from our database. They were divided into training cohort, validation cohort one and validation cohort two. A nomogram was constructed based on the risk factors affecting prognosis using a Cox proportional hazards regression model. The discrimination and calibration of the nomogram were evaluated by C-index, AUC and curve of calibration. The three cohorts were divided into low-risk and high-risk subgroups.

Inclusion Criteria:

• The diagnosis of TC in patients should be confirmed through endoscopic tumor biopsy or surgery to obtain tumor tissue for pathological confirmation under light microscope, and even further confirmed through immunohistochemical staining.
• Patients should accept surgery and obtain complete postoperative pathological reports in order to assess Masaoka-Koga staging.
• Patients who accepted surgery should be followed up at least six months or reached the endpoint event.

Exclusion Criteria:

• The patient had two types of primary tumors concurrently including TC.
• The tumor in the thymus was not primary but metastatic, having originated from a different primary site.
• The patient did not obtain a complete pathological report after surgery.