Study design
The present study was approved by the Internal Institutional Review Board (Cerrahpasa Medical Faculty, approval number 21263603-604.02.01-86518). The hospital medical records and charts of the patients were retrospectively reviewed. The data included demographics, tumor characteristics, operative findings, pathological outcomes, postoperative follow-up, and survival outcomes.
Preoperative comorbidities were assessed according to the Charlson Comorbidity Index [8]. The performance status was measured for each patient using the Eastern Cooperative Oncology Group performance score (ECOG PS) [9]. The Mayo Clinic system was used to classify the thrombus level [10]. Preoperative physical status was evaluated by the American Society of Anesthesiologists (ASA) scoring [11]. Surgery-associated complications were assessed based on the Clavien classification [12]. All pathological specimens were examined by a single pathologist team according to the recommendations of the UICC/American Joint Committee on Cancer [13]. Tumor nuclear grade was determined according to the Fuhrman grading system [14]
Overall survival (OS) was described as the time from the operation to the last visit in 18 surviving patients and as the time from the operation to death in 15 deceased patients. Disease-free survival (DFS) was defined as the time from the procedure to the metastatic process in 15 preoperative clinic M0 patients and as the time from the operation to the last visit in nine preoperative and postoperative clinical M0 patients.