Neutrophil-to-lymphocyte ratio as a prognostic predictor in adrenocortical carcinoma: a retrospective cohort study stratified by cortisol secretion status

Introduction

Adrenocortical carcinoma (ACC) is a highly malignant tumor characterized by rapid progression and poor prognosis (1,2). Complete surgical resection remains the only potentially curative treatment for ACC (3). Most patients present with advanced disease at diagnosis (4). Even with R0 resection, the recurrence rate is alarmingly high, ranging from 30% to 85% (5,6). First-line therapy for metastatic ACC, per clinical guidelines, consists of mitotane combined with etoposide, doxorubicin, and cisplatin. However, this regimen has limited efficacy and substantial toxicity. Minimally invasive preoperative assessments that yield predictive indicators can facilitate prognostic evaluation. This evaluation, together with information on financial costs, potential risks, and expected benefits, guides patients in making informed treatment decisions.

Chronic inflammation is a pivotal factor in the pathogenesis and progression of cancer (7). Numerous inflammatory biomarkers and scoring systems have been extensively studied for their prognostic significance in oncology. In cancer-related inflammation, neutrophils and lymphocytes exert opposing effects. Reduced lymphocyte counts in cancer patients can impair immune responses, increasing recurrence risk. Conversely, elevated neutrophil counts may promote tumor progression by secreting angiogenic and growth factors. The neutrophil-to-lymphocyte ratio (NLR), a composite measure of both cell types, has emerged as an extensively investigated inflammatory biomarker (8). Additionally, cancer-associated thrombocytosis promotes tumor progression by enhancing angiogenesis and adhesive molecule synthesis (9). Similarly, the platelet-to-lymphocyte ratio (PLR) correlates with adverse outcomes in various malignancies (10). Although preliminary studies have explored the prognostic value of NLR and PLR in ACC, our study provides new insights by evaluating these markers in a Chinese cohort. We also performed a preliminary analysis of factors associated with NLR and PLR in this population. We present this article in accordance with the STROBE reporting checklist (available at https://tcr.amegroups.com/article/view/10.21037/tcr-2025-aw-2335/rc).

Methods

Participants and study design

We retrospectively analyzed data from patients with pathologically confirmed ACC at The First Affiliated Hospital of Xi’an Jiaotong University between January 1985 and December 2020. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Ethics Committee of The First Affiliated Hospital of Xi’an Jiaotong University (No. XJTU1AF2021LSK-153). The Ethics Committee waived the requirement for written informed consent from patients due to the retrospective nature of the analysis. All patient data were anonymized and maintained confidentially. During telephone follow-up, verbal informed consent was obtained from each patient (or their legal representatives), and this consent was documented in the follow-up records maintained by the study team.

Data collection

Demographic, clinical, laboratory, and pathological data were collected retrospectively. The European Network for the Study of Adrenal Tumors (ENSAT) staging system was applied to classify the disease stage of all patients with ACC. Preoperative complete blood counts were available for all 45 patients, permitting calculation of NLR and PLR, and hormonal status was documented in every case. Ki-67 index values were missing for a minority of patients and were not imputed. Preoperative NLR and PLR were calculated from complete blood counts obtained before any surgical intervention or mitotane therapy, and no patient was known to be receiving chronic systemic glucocorticoid therapy for unrelated indications at the time of blood sampling. Patients with active infection, sepsis, or coexisting inflammatory conditions (e.g., hematological or autoimmune disorders) were excluded. Patients were followed up by telephone until December 2020 to assess prognosis.

To contextualize our cutoff selection, we conducted a systematic literature review in February 2025 to identify studies evaluating the prognostic value of NLR and PLR in ACC. We searched PubMed using the strategy: “(adrenocortical carcinoma) AND (neutrophil-to-lymphocyte ratio) OR (platelet-to-lymphocyte ratio) OR (PLR) OR (NLR)”. No date restrictions were applied. After removing duplicates, 10 articles were retrieved (11-20). Studies investigating non-prognostic outcomes, reporting non-significant findings for NLR/PLR, or not addressing the role of NLR/PLR were excluded (11-14). Key study characteristics, including country, sample size, cutoff values, and main conclusions, were extracted and summarized. The cutoff value of 3.9 for NLR was selected a priori based on previously published studies of ACC in which this threshold was associated with prognosis, rather than being derived from the present dataset, in order to minimize data-driven selection in this small cohort.

Pathological evaluation

All histopathological diagnoses and Ki-67 evaluations were performed by pathologists with expertise in adrenal tumors in the Department of Pathology, following institutional standard practice. The Ki-67 index was determined by manual counting of positively stained tumor nuclei in regions of highest labeling on immunohistochemically stained slides. For some early cases, archival histological material was unavailable for contemporary re-review, and Ki-67 values were obtained from original pathology reports. This non-uniform specimen availability may have introduced variability in Ki-67 assessment.

Statistical analysis

Continuous variables are presented as mean ± standard deviation for normally distributed data or median and interquartile range (IQR) for non-normally distributed data. Categorical variables are reported as numbers and percentages. Distributions of categorical and continuous variables were compared between groups using Fisher’s exact test, Chi-squared test, Mann-Whitney U test, or t-test as appropriate. Survival was estimated using the Kaplan-Meier method, and differences between curves were assessed with the log-rank test. Variables with P<0.05 in univariate analysis were included in the multivariate Cox proportional hazards regression model. The proportional hazards assumption was not formally tested using Schoenfeld residuals due to the limited number of events, which reduces the power of such tests. A two-sided P value <0.05 was considered statistically significant. Statistical analysis was performed with SPSS 23.0 software (IBM Corp., Armonk, NY, USA).

Results

Baseline characteristics

This retrospective study included 45 patients with ACC. The median follow-up time was 21 (IQR, 10–48) months. The majority of these patients had advanced disease, with 22 (48.89%) and 14 (31.11%) patients having ENSAT stage III and IV disease, respectively. Eleven patients (24.44%) exhibited endocrine dysfunction, all of whom were diagnosed with Cushing’s syndrome (CS). Most (75.56%) of the patients underwent open surgery, while 16 (35.56%) did not receive any adjuvant therapy. CS was diagnosed by an endocrinologist based on standard biochemical testing—including evaluation of the diurnal cortisol rhythm, and/or a low-dose dexamethasone suppression test—in combination with compatible clinical features of cortisol excess. Patients with biochemical evidence of cortisol excess in the absence of overt clinical features were not analyzed as a separate category; when hypercortisolism was judged clinically relevant, these cases were classified within the CS group. Detailed demographic and clinical characteristics are summarized in Table 1.

NLR and PLR cutoff values in the literature

To inform the selection of prognostic thresholds for NLR and PLR, we systematically summarized the relevant literature (Table 2). The included studies proposed varying cutoff values (e.g., the NLR ranged from 3.9 to 5) across diverse patient populations, indicating the lack of a standardized threshold.

Survival analysis and prognostic factors in ACC

Based on the established cutoff values (NLR =3.9; PLR =190), we assessed the prognostic utility of the NLR and PLR. Disease-specific survival (DSS) was the primary endpoint for evaluating long-term prognosis. Patients with an NLR ≤3.9 had significantly longer median DSS than those with an NLR >3.9 (46 vs. 18 months; P<0.001; Figure 1A). Similarly, a PLR ≤190 was associated with improved DSS as compared to a PLR >190 (36 vs. 18 months; P=0.006; Figure 1B).

Figure 1 Kaplan-Meier survival curves for patients with ACC. (A) Kaplan-Meier survival curve comparing the DSS between patients with NLR ≤3.9 and >3.9. (B) Kaplan-Meier survival curve comparing the DSS between patients with PLR ≤190 and >190. (C) Kaplan-Meier survival curve for patients with advanced-stage ACC. (D) Kaplan-Meier survival curve for patients with ACC with and without CS. (E) Kaplan-Meier survival curve of NLR in non-CS patients. (F) Kaplan-Meier survival curve of PLR in non-CS patients. ACC, adrenocortical carcinoma; CS, Cushing’s syndrome; DSS, disease-specific survival; NLR, neutrophil-to-lymphocyte ratio; PLR, platelet-to-lymphocyte ratio.

In the advanced-stage (III–IV) ACC subgroup, NLR >3.9 remained a significant predictor of poor prognosis. The median DSS was 36 months for patients with NLR ≤3.9 versus 12 months for those with NLR >3.9 (P=0.002; Figure 1C).

Univariate Cox analysis indicated that the significant risk factors for poor DSS were vascular invasion [hazard ratio (HR) =2.27, 95% confidence interval (CI): 1.06–4.85, P=0.04], distant metastasis (HR =4.12, 95% CI: 1.89–8.96, P<0.001), Ki-67 index (HR =1.05, 95% CI: 1.03–1.08; P<0.001), advanced ENSAT stage (HR =5.20, 95% CI: 1.56–17.36, P=0.007), no surgery (HR =3.03, 95% CI: 1.04–8.84, P=0.04), an NLR >3.9 (HR =4.18, 95% CI: 1.91–9.13, P<0.001), and a PLR >190 (HR =2.66, 95% CI: 1.25–5.69, P=0.01) (Table 3). Multivariate analysis confirmed that the independent prognostic factors were Ki-67 index (HR =1.04, 95% CI: 1.01–1.07; P=0.01), advanced ENSAT stage (HR =45.64, 95% CI: 2.88–724.60, P=0.007), and NLR >3.9 (HR =4.12, 95% CI: 1.25–13.61, P=0.02). An NLR exceeding 5 was not found to be an independent risk factor for adverse outcomes in patients with ACC.

Stratified analysis according to CS status

The median NLR was significantly higher in patients with ACC and CS [5.07 (IQR, 4.38–7.35)] than in those without CS [3.70 (IQR, 2.48–5.42); P=0.047; Table S1]. However, the presence of CS did not significantly affect DSS (P=0.58; Figure 1D).

Among patients without CS, an NLR ≤3.9 was associated with significantly better prognosis as compared to an NLR >3.9 (median DSS: 36 vs. 19 months; P=0.001; Figure 1E), while PLR showed no prognostic significance (Figure 1F).

In patients without CS, elevated NLR was significantly associated with local invasion (P=0.002), vascular invasion (P=0.04), and distant metastasis (P=0.01). PLR was also higher in patients with local invasion (P=0.002) and distant metastasis (P=0.02) (Table 4).

Univariate analysis of non-CS patients identified vascular invasion, distant metastasis, Ki-67 index, advanced ENSAT stage, and NLR as significant risk factors. However, none remained independent predictors in the multivariate analysis (Table 5).

Discussion

In this exploratory study, we found that a preoperative NLR >3.9 was an independent predictor of poor DSS in Chinese ACC patients, alongside established factors like high Ki-67 index and advanced ENSAT stage. Although both NLR and PLR were significantly associated with survival in univariate analysis, only NLR retained independent prognostic value in the multivariate model, suggesting that NLR may be a more robust inflammatory biomarker in this setting.

Our findings are consistent with some studies but diverge from others. The prognostic value of NLR and PLR in ACC is supported by multiple studies (15-20), though reported optimal cutoff values vary considerably. For instance, Bagante et al. (20) and Mangone et al. (15) indicated that a PLR >190 and an NLR ≥5 were predictive of poorer survival, whereas Solak et al. (17) identified an NLR >3.9 as a significant threshold, aligning with our results. The value of a lower NLR cutoff value of 3.9 in our cohort may reflect important ethnicity-dependent variations in baseline inflammatory markers, as well as differences in cohort characteristics (21,22).

Our study extends previous findings in several key aspects. First, by validating an NLR >3.9 in a Chinese cohort, we highlight the importance of considering ethnicity when applying this biomarker. More importantly, we systematically evaluated the influence of hypercortisolemia. We confirmed that patients with CS exhibit significantly higher NLR levels, likely due to glucocorticoid-induced neutrophilia and lymphopenia. After excluding this confounder, elevated NLR remained correlated with aggressive tumor features—including local invasion, vascular invasion, and distant metastasis—in non-CS patients. Focusing on the non-CS subgroup, an elevated NLR (>3.9) was significantly associated with shorter DSS in univariate analysis. However, in the subsequent multivariable analysis of this subgroup—likely underpowered due to the limited number of events—NLR did not retain independent statistical significance. This pattern suggests that the systemic inflammation reflected by NLR is intimately linked to the aggressive phenotype of ACC, even in the absence of cortisol excess. However, the prognostic information it provides regarding survival may be largely captured by or intertwined with other established markers of tumor aggressiveness (such as ENSAT stage and Ki-67 index) when subjected to multivariable adjustment. Therefore, while our data robustly confirm the association between NLR and aggressive tumor biology across all patients, its role as an independent predictor of survival specifically in non-CS patients remains uncertain and warrants validation in larger, dedicated cohorts. We did not model NLR as a continuous variable or compare alternative data-driven cutoffs, this lack of formal cutoff optimization is a study limitation.

The independent prognostic value of NLR in the overall cohort underscores its potential for clinical utility. If validated in larger studies, this low-cost and readily available biomarker could enhance preoperative risk stratification, helping to identify patients who might benefit from more aggressive treatment or enrollment in clinical trials. Furthermore, given the emerging role of immunotherapy in oncology, our findings support further investigation into whether NLR can predict response to immune checkpoint inhibitors in ACC. This is particularly relevant as hypercortisolism has been implicated in resistance to immunotherapy (23-25), and our data suggest that both cortisol excess and tumor-related inflammation contribute to an elevated NLR.

Although PLR was associated with DSS in univariate analysis, this association was attenuated and lost statistical significance in the multivariable model. This pattern may reflect collinearity between NLR and PLR, as both indices incorporate lymphocyte count in the denominator, as well as the stronger and more stable prognostic signal carried by NLR in this small cohort. In addition, the limited sample size and number of disease-specific deaths reduce the power to detect independent effects of PLR, and we did not formally quantify collinearity (for example, by correlation coefficients or variance inflation factors); therefore, the findings related to PLR should be interpreted with caution.

However, our study involved certain limitations that should be acknowledged. First, its retrospective, single-center design with a small sample size limits the generalizability of the findings and statistical power, especially in subgroup analyses. Second, and most critically, the statistical analyses are subject to constraints inherent to small cohorts. The low events-per-variable ratio in our multivariable Cox model increases the risk of overfitting. This is strongly suggested by the extraordinarily wide confidence interval for ENSAT stage in the multivariate model, along with the very high hazard ratio. Therefore, the point estimate for this variable should be interpreted with extreme caution, and the finding is primarily indicative of a strong association rather than a precise quantitative effect. Furthermore, the proportional hazards assumption could not be reliably verified due to the limited power of formal tests in this setting. The study spans a long period (1985–2020), during which diagnostic practices, surgical techniques, and therapies—particularly mitotane use and imaging—evolved significantly. These changes may have affected staging and treatment, introducing temporal heterogeneity. Although we considered stratifying by treatment era (e.g., pre- vs. post-2005), the small sample size precluded this, and this potential source of bias should be considered when interpreting the results. Furthermore, some pathological samples were unavailable for contemporary biomarker analysis. Future prospective, multi-institutional studies with larger, ethnically diverse cohorts are needed to confirm the optimal NLR and PLR thresholds and to determine their potential as predictive biomarkers for immunotherapy among patients with ACC. Future studies should integrate these markers with molecular data and new therapies to improve ACC diagnosis and prognosis (26).

Conclusions

In conclusion, our data indicate that a preoperative NLR >3.9 may serve as a simple and accessible prognostic marker for DSS in patients with ACC, correlating with both hypercortisolism and aggressive tumor characteristics. The integration of this biomarker into risk stratification models, pending future validation, could potentially help in tailoring individualized treatment strategies.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://tcr.amegroups.com/article/view/10.21037/tcr-2025-aw-2335/rc

Data Sharing Statement: Available at https://tcr.amegroups.com/article/view/10.21037/tcr-2025-aw-2335/dss

Peer Review File: Available at https://tcr.amegroups.com/article/view/10.21037/tcr-2025-aw-2335/prf

Funding: This work was supported by Key Research and Development Program of Shaanxi Province (Nos. 2023-ZDLSF-40 and 2021LL-JB-06), which did not participate in the design of the study; the collection, analysis, and interpretation of data; or the writing of the manuscript.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tcr.amegroups.com/article/view/10.21037/tcr-2025-aw-2335/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. Ethical approval was obtained from the Ethics Committee of The First Affiliated Hospital of Xi’an Jiaotong University (No. XJTU1AF2021LSK-153). The Ethics Committee waived the requirement for written informed consent from patients due to the retrospective nature of the analysis. All patient data were anonymized and maintained confidentially. During telephone follow-up, verbal informed consent was obtained from each patient (or their legal representatives), and this consent was documented in the follow-up records maintained by the study team.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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