Imaging Accurately Stages Nodal Squamous Cell Carcinoma Except in Immunosuppression

The Challenge of Nodal Staging in High-Risk Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma remains the second most prevalent skin malignancy, and while localized excision is often curative, a high-risk subset of patients faces a substantial threat of morbidity and mortality [1, 2]. Identifying nodal metastases at the earliest possible stage is critical, as regional involvement necessitates a shift toward aggressive interventions such as lymph node dissection or adjuvant radiotherapy (radiation treatment administered after primary surgery to reduce the risk of local or regional recurrence) [3, 4]. Current staging systems, including the American Joint Committee on Cancer and Brigham and Women’s Hospital frameworks, provide a structure for risk stratification but do not definitively establish the optimal imaging modality for baseline evaluation [5, 6]. This diagnostic uncertainty is particularly acute in immunosuppressed patients, who are known to develop more aggressive tumors with higher rates of recurrence [3, 7]. A new study now provides evidence-based insights into the comparative performance of various imaging modalities for nodal staging in these high-risk populations.

Prospective Comparison of Three Staging Modalities

To address the lack of consensus regarding baseline nodal staging, researchers conducted a prospective, multicenter, paired diagnostic study across 13 tertiary dermato-oncology centers in Spain between January 2022 and April 2025. The study enrolled 155 patients with histologically confirmed high-risk cutaneous squamous cell carcinoma, specifically targeting those with stage T2b or T3 disease, or stage T2a tumors presenting with additional high-risk features. This cohort reflected the typical demographic for advanced skin malignancies, with a median age of 80.3 years (interquartile range, 74.4 to 85.5 years). The gender distribution was predominantly male, comprising 121 patients (78.1%), while 34 patients (21.9%) were female. This demographic profile is particularly relevant for clinicians, as elderly patients often present with multiple comorbidities that can complicate both surgical and radiological management.

Imaging Shows Superior Sensitivity to Physical Examination

The clinical progression of high-risk cutaneous squamous cell carcinoma often involves rapid regional spread, as evidenced by the finding that 12 patients (7.7%; 95% CI, 4.3% to 13.4%) developed nodal metastases within 3 months after surgery. When evaluating the effectiveness of baseline staging, the researchers identified a stark contrast between manual palpation and radiological assessment. Physical examination proved largely insufficient for the early detection of nodal involvement, yielding a sensitivity of only 8.3% (95% CI, 0.2% to 38.5%). In comparison, imaging modalities provided a much higher detection rate for subclinical disease. Ultrasonography showed the highest overall sensitivity at 63.6% (95% CI, 30.8% to 89.1%), while the sensitivity for computed tomography (CT) was 54.5% (95% CI, 23.4% to 83.3%). Despite the differences in sensitivity, all three diagnostic methods maintained high levels of specificity, which is critical for avoiding unnecessary invasive procedures. The specificity was 99.3% (95% CI, 96.2% to 100%) for physical examination, 95.6% (95% CI, 90.6% to 98.4%) for ultrasonography, and 95.0% (95% CI, 90.0% to 98.0%) for CT. For clinicians determining the most appropriate staging workflow, the study highlights that ultrasonography and CT demonstrated almost perfect agreement with a kappa (κ) of 0.87 (95% CI, 0.72 to 1.00). This high level of concordance (a statistical measure of how often two different tests agree on a diagnosis beyond what would be expected by chance) suggests that these two imaging modalities can be used interchangeably based on institutional resources or patient factors. However, the concordance between imaging and physical examination was poor, further emphasizing that manual assessment alone is an unreliable predictor of nodal status in high-risk cases.

The Diagnostic Gap in Immunosuppressed Populations

The diagnostic utility of baseline imaging depends heavily on the patient's immune status, showing a stark divergence in performance between subgroups. In patients with intact immune systems, both imaging modalities demonstrated exceptional diagnostic accuracy. For the immunocompetent subgroup, ultrasonography achieved 100% sensitivity (95% CI, 54.1% to 100%) and an area under the receiver operating characteristic curve (AUROC) of 0.98 (95% CI, 0.96 to 1.00). The AUROC is a statistical measure of a test's overall ability to discriminate between diseased and non-diseased states, where 1.0 represents a perfect diagnostic test. Similarly, computed tomography (CT) achieved 100% sensitivity (95% CI, 47.8% to 100%) and an AUROC of 0.98 (95% CI, 0.96 to 1.00) in these patients. These findings suggest that for the average patient with high-risk cutaneous squamous cell carcinoma, either modality is highly reliable for identifying nodal involvement during initial staging. However, the reliability of these tools decreased significantly when applied to patients with compromised immune systems. In the immunosuppressed cohort, ultrasonography sensitivity declined to 20.0% (95% CI, 0.5% to 71.6%) with an AUROC of 0.57 (95% CI, 0.37 to 0.77), indicating performance only slightly better than random chance. The results for CT were even lower in this group, with sensitivity falling to 16.7% (95% CI, 0.4% to 64.1%) and an AUROC of 0.55 (95% CI, 0.38 to 0.72). This failure to detect early disease is a critical clinical concern, as the researchers observed that metastases in the immunosuppressed subgroup often emerged abruptly during follow-up despite negative baseline staging. These disparities highlight a significant limitation in current staging protocols. While imaging is highly effective for immunocompetent individuals, the high rate of false negatives in immunosuppressed patients suggests that a negative baseline scan cannot be used to rule out the rapid development of regional disease. For the practicing clinician, these data emphasize the necessity of intensive clinical surveillance and potentially more frequent imaging intervals for the immunosuppressed. The findings reveal a clear need for tailored recommendations in future clinical practice guidelines to address the unique diagnostic challenges and elevated risks faced by this specific patient population.

References

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