Contrast tomography (CT) performed to detect nodal metastasis for high-risk cutaneous squamous cell carcinomas of the head and neck has a high negative predictive value but a poor positive predictive value

Palpable adenopathy on exam 13/40 Average tumor size 5.5 cm Recurrent 19/40 Perineural invasion 16/40 Lymphovascular invasion 6/40 Immunosuppressed status 10/40 Contrast tomography (CT) performed to detect nodal metastasis for high-risk cutaneous squamous cell carcinomas of the head and neck has a high negative predictive value but a poor positive predictive value AJCC8 Stage* T1 1 T2 0 T3 33 T4a 1 T4b 5 BWH Stagey T1 1 T2a 9 T2b 24 T3 6

To the Editor: In contrast to the considerable data on imaging for staging oropharyngeal head and neck squamous cell carcinoma (HNSCC), the accuracy of contrast tomography (CT) to detect nodal metastases in cutaneous squamous cell carcinoma (cSCC) is not established. 1,2We performed a retrospective study assessing sensitivity and specificity of CT to detect nodal metastasis among high-risk cSCC of the head and neck.Our reference standard (ie, ''true'') result was the conclusion from nodal pathology sampling.This was compared to the result of CT studies performed prior to nodal sampling.Cases were identified using a combination of the relevant International Classification of Diseases (ICD 9/10) codes and nodal sampling Current Procedural Terminology (CPT) codes in the electronic medical record over a 10-year interval from July 1, 2011 to June 30, 2021.This resulted in a cohort of 38 patients with 40 tumors.Nodal sampling type varied; however, most cases (34/40) received neck dissection (including selective or radical neck dissection) and/or parotidectomy.Neck dissection and/or parotidectomy were performed due to the estimated high risk of metastasis in these patients.This was based on the advanced average size of 5.5 cm or due to imaging or examination findings suggesting metastasis.In those who did not have neck dissection and/or parotidectomy, 3 patients had sentinel node biopsies, 2 had fine needle aspirations, and 1 case had nodal excision.All patients had CT prior to surgery with 37 out of 40 being performed with contrast.Information was collected on each tumor to better characterize the cohort (Table I).
The calculated sensitivity of imaging to detect nodal metastasis in our cohort was 90% [95% confidence interval: 70% to 97%] while specificity was 55% [34% to 74%].Values were re-calculated after excluding 13 patients with palpable adenopathy due to concern of possibly overstating the sensitivity.Sensitivity then became more modest at 78% [45% to 94%] and specificity was similar at 61% [39% to 80%].
Based on our data and an estimated metastasis rate of 23.8% [14.8% to 38.4%] for T2b tumors as was found in a 2019 study by Dr Ruiz and colleagues, 3 the positive predictive value of CT to detect metastasis in a T2b tumor without clinical adenopathy is 38% [20% to 62%] and the negative predictive value is 90% [72% to 97%] (Table II).
We conclude that CT likely has some utility in ruling out nodal metastasis, however the false positive rate is high.We suspect the reason for the high false positive rate may be due to enlarged reactive nodes in response to the primary tumor.With such a high false positive rate, sampling of an enlarged node should be considered prior to proceeding with neck dissection.
Limitations to this study include retrospective design with small sample size as well as improvements in imaging technology over time.We chose nodal sampling as the reference standard as opposed to long-term followup as followup was often short and variable.This emulates the oropharyngeal SCC literature which predominantly uses radical neck dissection as the reference standard when evaluating imaging accuracy. 4Nodal sampling cannot detect all metastases and therefore the sensitivity may be overstated.Prospective data with long-term followup assessing multiple imaging modalities is warranted.
The project was supported by the Clinical and Translational Science Award (CTSA) program, through the NIH National Center for Advancing Translational Sciences

Table I .
Tumor characteristics and staging Brigham and Women's Hospital Tumor Classification System for Cutaneous Squamous Cell Carcinoma. 3ª 2023 by the American Academy of Dermatology, Inc. Published by Elsevier Inc.This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).(NCATS), grant UL1TR002373.The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.We also thank the University of Wisconsin Carbone Cancer Center for providing support for statistical analysis and the University of Wisconsin Foundation for providing grant support.Division of Otolaryngology-Head & Neck Surgery, UW Department of Surgery, Clinical Science Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin c ; Department of Pathology and Laboratory Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin d ; and Department of Biostatistics and Medical Informatics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.e