141 - Effect of Cisplatin Cycles on Prognosis for Locally Advanced Cervical Cancer Patients Treated with Concurrent Chemoradiotherapy: A Long-Term Follow-Up, Large Cohort Study

Z. Zeng, X. Yang, J. Yan, K. Hu, and F. Zhang; Department of Radiation Oncology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China

Purpose/Objective(s): To assess the impact of cisplatin cycles on both overall survival (OS) and disease-free survival (DFS) in locally advanced cervical cancer (LACC) patients undergoing concurrent chemoradiotherapy (CCRT), and to build a nomogram-based prognostic stratification to identify LACC patients who might benefit from = 5 cycles of cisplatin. Materials/

Methods: A total of 918 patients with LACC who underwent CCRT at our hospital were retrospectively enrolled. The difference in survival outcomes between the < 5 cycles and = 5 cycles groups were compared using the paired Log-rank test. Subgroup analysis was further conducted to explore the survival differences between the = 5 cycles and < 5 cycles groups in different subpopulations, including age, histology, tumor size, squamous cell carcinoma antigen (SCC Ag), and Federation International of Gynecology and Obstetrics (FIGO) stage. Univariate and multivariate Cox regression analyses were performed in the <5 cycles group to identify independent risk factors, and a nomogram was developed accordingly. The patients were divided into two risk subgroups according to the total points derived from the nomogram, and the survival outcomes between the < 5 cycles and = 5 cycles groups were compared in each risk strata.
Results: The 5-year OS and DFS were 76.7% (95% CI: 74.3–79.9%) and 86.1% (95% CI: 84.6–87.6%) (p = 0.002) and 68.7% (95% CI: 66.1%–71.3%) and 78.3% (95%CI: 76.6%–80.0%) (p = 0.0016) for the < 5 and = 5 cycles groups, respectively. In subgroup analysis, the survival benefit of = 5 cycles could be maintained in patients with squamous disease (p = 0.0031 in OS; p = 0.0019 in DFS), patients with SCC > 1.5 ng/mL (p = 0.0096 in OS; p = 0.019 in DFS), patients with tumor size > 4 cm (p = 0.0036 in OS; p = 0.0011 in DFS), and patients with stage I/II disease (p = 0.0041 in OS; p = 0.014 in DFS). A nomogram incorporating size, SCCAg, and FIGO stage was constructed, and patients were divided into two risk groups (low-risk: total points < 101; high-risk: total points = 101). Receiving = 5 cycles showed superiority in OS (p = 0.0025) and DFS (p = 0.008) over < 5 cycles in the low-risk subgroup; however, this survival benefit could not be maintained in the high-risk subgroup (p = 0.130 in OS; p =0.093 in DFS).
Conclusion: Receiving = 5 cycles of cisplatin improved OS and DFS in LACC patients who received CCRT when compared with < 5 cycles. A nomogram was constructed and the newly defined low-risk patients might gain significant OS and DFS benefit from receiving = 5 cycles.