Epidemiology and treatment outcomes of cutaneous squamous cell carcinoma extending to the temporal bone

Abstract

Background Accurate epidemiological and outcomes data regarding cutaneous squamous cell carcinoma (cSCC) extending to the temporal bone is lacking. Methods Retrospective analysis of 167 Australian patients with primary and peri‐temporal bone cSCC. Results cSCC extending from secondary subsites (93.4%) was 14 times more frequent than primary temporal bone SCC (6.6%). For patients who underwent curative surgery ± post‐operative radiotherapy (n = 146, 87.4%), 5‐year disease‐free survival, locoregional recurrence‐free survival, disease‐specific survival, and overall survival was 53.0%, 59.4%, 67.9%, and 44.7%, respectively. External ear and pre‐auricular tumors, salvage surgery, tumor size (≥40 mm medial‐lateral), nodal disease, and involved margins were negative predictors of survival in multivariable analysis. Conclusion In regions of high sun exposure, cSCCs extending to the temporal bone are more common than primary cancers. Outcomes are improved with clear margins, justifying the need for radical resection. Further research regarding pre‐auricular cancers is required given poorer associated survival outcomes.

Fascial layers encountered in the lateral skull base region: A cadaveric and radiological analysis

“…However, in order to gain appropriate access and visualization of these layers, the styloid process and possibly VII may also require excision, if not already involved with tumor. In our previous series of cSCCs requiring TBR, of the patients with tumors extending close (≤5 mm) to or encasing/eroding the styloid process (a surrogate for this fascial plane), 55% had VII palsy pre‐operatively and 89% who proceeded to surgery underwent resection of VII 1 . Yet, the question remains as to the benefit of resecting this fascial plane with regards to its effectiveness as a barrier to spread of malignancy.…”

“…As such, tumors in this region can be challenging to excise, especially when disease extends to crevices around the temporal bone and temporomandibular joint. In our case series of patients with cutaneous squamous cell carcinoma (cSCC) requiring temporal bone resection (TBR) from Queensland (Australia), preauricular tumors had the highest rates of involved margins and the worst survival outcomes compared to other subsites of origin 1 . These findings have necessitated further research to be conducted, specifically in relation to the fascial planes of the peri‐temporal bone region and the role they can play in surgical resections.…”

Patterns of spread and anatomical prognostic factors of pre‐auricular cutaneous squamous cell carcinoma extending to the temporal bone

“…5,25,[27][28][29] However, in our previous series, which included all patients with cSCC requiring TBR, pathological bone invasion did not affect survival outcomes. 9 We suspect this discrepancy may be due to a number of reasons. Firstly, the extent of bony erosion, which may impact prognosis, was not accounted for in either of our studies.…”

“…Staging advanced pre‐auricular cSCCs is also an issue that needs addressing. In our previous case series, the majority of patients with cSCC requiring TBR were Stage III or IV (96%) according to the American Joint Committee on Cancer (AJCC) 8th edition, due to all cutaneous tumors being classified as T3 at a minimum and those of nodal origin as N3b due to extranodal extension (ENE) 9,16 . However, survival was not uniform across the cohort.…”

“…In our review of patients requiring temporal bone resection (TBR) for malignancy at our institution (Princess Alexandra Hospital, Brisbane, Australia), cutaneous squamous cell carcinoma (cSCC) was the most common histopathological subtype (75.2%), and over 90% originated from the peri‐temporal bone region compared with <10% from the EAC 8 . In a follow‐up study of the cSCC subgroup, pre‐auricular tumors, encompassing cutaneous and nodal deposits, not only formed the majority (43.7%), but also had the highest rates of involved margins (39.4%) 9 . Additionally, pre‐auricular cSCCs had the worst survival outcomes compared with other subsites of origin, with a 5‐year disease‐free survival (DFS) and disease‐specific survival (DSS) of 34.1% and 48.1% versus 68.8% and 85.1%, respectively.…”