This single-center analysis evaluated the prognostic significance of PD-L1 expression in oral squamous cell carcinoma (OSCC) patients who underwent curative-intent surgery. The investigation aimed to clarify whether PD-L1, measured by the Combined Positive Score (CPS), is independently associated with survival or recurrence outcomes in a large consecutive clinical cohort.
The study included 156 consecutive OSCC patients treated surgically. PD-L1 expression was assessed using the Combined Positive Score (CPS). The prespecified primary threshold for PD-L1 positivity was CPS ≥ 10. Two sensitivity thresholds were also examined: CPS ≥ 1 and CPS ≥ 20. Using the primary cutoff (CPS ≥ 10), 120 of 156 patients (76.9%) were classified as PD-L1–positive. The authors report that PD-L1 status was not associated with any clinicopathological parameter evaluated in the cohort.
Survival and recurrence were analyzed using Kaplan–Meier estimates with log-rank tests and Cox proportional hazards regression with multivariable adjustment for key confounders. Endpoints included overall survival (OS), disease-free survival (DFS), local recurrence–free survival or local recurrence control rate (LRCR), and nodal control rate (NCR). Sensitivity analyses repeated the primary models at alternate CPS cutoffs (≥ 1 and ≥ 20).
At three years, outcome estimates were comparable between PD-L1–positive and PD-L1–negative patients when using the prespecified CPS ≥ 10 cutoff. Reported 3-year estimates were:
In multivariable Cox regression neither binary PD-L1 classification (positive vs negative) nor continuous CPS values were independently associated with OS, DFS, LRCR, or NCR at CPS ≥ 10. The authors further report no evidence of effect modification by disease stage.
Results at the higher sensitivity cutoff (CPS ≥ 20) were concordant with the primary analysis (no independent associations). At the lower threshold (CPS ≥ 1), PD-L1 positivity was associated with improved overall survival (reported hazard ratio 0.280; 95% CI 0.106–0.745; p = 0.011). The report emphasizes that this finding stems from a very small PD-L1–negative reference group at that cutoff and should not be interpreted as robust evidence of prognostic value.
When analyses were stratified by receipt of adjuvant therapy, PD-L1 positivity was associated with improved DFS among patients who did not receive adjuvant treatment. This association was not observed in patients who received adjuvant therapy. The report does not provide additional mechanistic explanation for the differential effect and treats this as an observation within the cohort.
Mean follow-up in the cohort was 15.7 ± 12.5 months. The authors highlight that this relatively short observation period limits the ability to draw conclusions about late recurrences or long-term survival. They caution that the isolated association seen at CPS ≥ 1 is likely unstable because of the small size of the PD-L1–negative comparator group at that threshold. No other significant limitations beyond limited follow-up are detailed in the abstract.
In this large single-center cohort of surgically treated OSCC patients, PD-L1 expression measured by CPS was not independently associated with short-term survival or recurrence using the prespecified threshold of CPS ≥ 10, nor at CPS ≥ 20. An apparent overall survival benefit at CPS ≥ 1 was acknowledged but judged not robust. The authors conclude that PD-L1 by CPS should not be considered a reliable standalone prognostic biomarker in the early postoperative period for OSCC based on the presented data.
The authors declared no potential conflicts of interest and no competing interests in relation to this research and its publication.