Abstract
INTRODUCTION: Penile cancer (PC) is a lethal malignancy with no effective prognostic biomarker. We aim to investigate associations between trajectories of squamous cell carcinoma antigen (SCC-A) and patient outcomes after chemotherapy based on paclitaxel, ifosfamid, and cisplatin (TIP) regimen. METHODS: Consecutive AJCC staging III/IV PC patients who received TIP chemotherapy and repeated SCC-A measurements in 2014-2022 were analyzed. Latent class growth mixed (LCGM) models were employed to characterize patients' serum SCC-A trajectories. Patient survival, and clinical and pathological tumor responses were compared. Inverse probability treatment weighting was used to adjust confounding factors. RESULTS: Eighty patients were included. LCGM models identified two distinct trajectories of SCC-A: low-stable (40%; n = 32) and high-decline (60%; n = 48). Overall survival (HR [95% CI]: 3.60 [1.23-10.53], p = 0.019), progression-free survival (HR [95% CI]: 11.33 [3.19-40.3], p < 0.001), objective response rate (37.5% vs. 62.5% p = 0.028), disease control rate (60.4% vs. 96.9% p < 0.00), and pathological complete response rate (21.2% vs. 51.9%, p = 0.014) were significantly worse in the high-decline arm. CONCLUSION: PC patients' SCC-A change rate was associated with tumor response and patient survival after TIP chemotherapy. SCC-A might assist tumor monitoring after systemic therapies.