Prediction score for lymph node metastasis from cutaneous squamous cell carcinoma of the external ear

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Abstract

Aims

The frequency of lymph node metastasis (LNM) is higher in cutaneous squamous cell carcinoma (cSCC) of the ear than in other head and neck cSCCs. Nodal dissemination is associated with a significantly worse prognosis and disease-specific survival. The aim of this study was to establish a prediction model for LNM in patients with cSCC of the ear.

Materials and methods

Tumour characteristics of 353 patients with ear cSCC were analysed to assess differences between those with and without LNM and to calculate a prediction score for LNM occurrence.

Results

Regional LNM occurred in 10.5% of patients. Five-year disease-specific survival was significantly lower in the LNM group than in the control group (59% vs. 99%; p < 0.001). Recurrence number, invasion of cartilage, tumour depth, and tumour grading were the most important predictors for LNM, with correct prediction of LNM in 94.0% of cases. Our prediction score stratified patients into high and low risk groups (p < 0.001) with a sensitivity of 89.2%, a specificity of 94.6%, and an overall accuracy of 94.1%.

Conclusion

Our new prediction model was able to accurately identify patients at high risk of LNM who may benefit from elective lymph node surgery.

Introduction

Cutaneous squamous cell carcinoma (cSCC) is the second most common type of skin cancer, with an incidence of 30 new cases per 100,000 people per year in Europe, and the incidence continues to rise by 4–8% per year.1, 2, 3 The ears are a frequent site of cSCC occurrence in the head and neck area, with cSCC being the most common histological type of cancer of the auricle.3, 4, 5, 6, 7

cSCC of the ear most often develops in the helix and antihelix, followed by the retroauricular region and cavum conchae.8, 9 This malignancy usually develops slowly, and the currently reported frequency of initial regional lymph node metastasis (LNM) ranges from 4% to 11%8, 10, 11, 12, 13, 14, 15; however, rates of upto 37% have also been previously described.16, 17 The development of secondary LNM ranges from 6% to 13%; therefore, the total mean risk of LNM in cSCC of the external ear is approximately 15.5%, a significantly higher rate than that for overall cSCC.2, 3, 18 Five-year overall survival rates for patients with cSCC of the ear without LNM are 87–95%, whereas those in patients with LNM decrease to 25–50%.4, 10, 11, 15, 17, 19, 20 In general, LNM is the most important prognostic factor in patients with head and neck cSCC.2, 21 Previous studies in 2 Australian cancer centres analysed prognostic factors in patients with metastatic cSCC.22, 23 While characteristics of the primary tumour, with the exception of histologic differentiation (grading), had only limited prognostic relevance, immunosuppression and extracapsular spread in nodal metastases were significantly associated with a poor outcome. This research group also developed a revised staging system for head and neck cSCC with nodal metastasis, taking into account the number and size of involved lymph nodes.24

Therefore, identifying patients with cSCC of the ear who are at high risk of LNM is crucial for adequate lymph node management and for improving outcomes in these patients. Various prognostic factors for LNM in ear cancer have been reported4, 8, 10, 11, 12, 13, 14, 15, 16, 19, 20, 25, 26, 27; however, different studies have reported inconsistent and even conflicting results. Moreover, a standardized definition of “high risk” patients who would benefit from elective lymph node surgery has not yet been established.11, 13, 14, 15

Therefore, the objective of this study was to identify clinically useful, assessable preoperative prognostic factors for LNM from cSCC of the ear and to develop a prediction model for LNM to improve outcomes in these patients.

Section snippets

Patients

Consecutive patients with histologically proven cSCC of the ear who were treated surgically between 2005 and 2011 were retrospectively identified from our institutional database.

This study was approved by the local ethics committee (Ethical Committee of the Westphalian Wilhelms-University Muenster, Approval-No. 2006-088-f-S) and was conducted in accordance with the Guidelines for Good Clinical Practice and in compliance with the Declaration of Helsinki. All participating patients provided

Results

In total, 353 patients were eligible for inclusion in this study (LNM group: n = 37; control group: n = 316). Eight of the LNM cases were identified during primary lymph node surgery, and 29 were identified during the follow-up period prior to secondary lymph node surgery (Table 1). The median time to nodal relapse was 8.2 months (mean 10.0; standard deviation [SD] 6.1; range 2.4–30.5 months). Among the 8 patients with primary LNM, 3 developed cervical metastases, 3 developed parotideal

Discussion

The distributions of patient characteristics in our study population were similar to those in previously published epidemiologic studies of ear cancer.8, 10, 11, 13, 15, 16, 17, 19, 28

Of note, this study included a relatively large number of patients (n = 353). Only one recent publication investigating LNM in ear cancer included more cases (n = 468)10; other previously published articles reported data of smaller study populations.11, 19

In our study, among 30 cases of primary lymph node

Conflict of interest statement

None declared. All authors declare that there are no competing interests.

No prior or subsequent publication

Neither the submitted article nor any similar manuscript concerning ear cancer, in whole or in part, other than an abstract, has been submitted, published, or is in press elsewhere.

Authors' contributions

KW conceived the study, contributed to interpretation of data, and was involved in drafting the manuscript. JK designed and performed data acquisition and helped to draft the manuscript. SS analysed and interpreted the data and contributed to manuscript drafting. MK contributed to study conception and design and revised the manuscript. HJS gave important intellectual content to data interpretation and critically revised the manuscript. CH provided important content to study design, data

Funding

None.

Acknowledgements

We thank Ms. Margret Leygraf and colleagues for their skilled technical assistance.

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