P65: A review of radiological imaging in high-stage cutaneous squamous cell carcinomas

Ciara Drumm,¹ Rebecca Hellen,¹ Aoife Moloney,¹ Roisin Dolan,² Caitriona Lawlor,² Aoife Lally^1,3 and Bláithín Moriarty^1,3

¹Charles Centre of Dermatology and ²Department of Plastic and Reconstructive Surgery, St Vincent’s University Hospital, Dublin, Ireland; and ³Charles Institute of Dermatology, University College Dublin, Dublin, Ireland

Cutaneous SCC (cSCC) is the second most common malignancy in humans and although most cSCCs portend an excellent prognosis a small proportion have a high risk of poor outcomes. Three staging systems are currently widely used – the American Joint Committee on Cancer 8 (AJCC8), the Brigham and Women’s Hospital (BWH) and the Union of International Cancer Control (UICC) – none of which is validated for cSCC in Ireland. It has recently been demonstrated that BWH had the highest specificity (93%), positive predictive value (PPV; 13%) and C-index (0.84). The biggest limitation of current staging systems is a low PPV; thus, it is challenging to identify those at risk of poor outcomes, which may justify more thorough baseline staging and ongoing surveillance. There is limited evidence on the utility, timing and optimal modality of radiology imaging in the staging of cSCC that may aid risk stratification and tumour staging. The 2020 British Association of Dermatologists guidelines for the management of cSCC recommend imaging for patients with AJCC8 ≥ tumour stage 2 (T2) cSCCs and BWH ≥ T2b cSCCs. The aim of this study was to evaluate imaging performed for cSCC at our hospital. All cSCCs excised from 2018 to 2021 were identified from the cSCC database. In total, 681 cSCCs were excised from 2018 to 2021 inclusive. The majority (67.1%) were in men, the median (SD) age of whom was 77.9 (10.7) years (range 23–101). Fifty-nine patients with 71 (10.4%) cSCCs underwent baseline staging imaging. The most common imaging modality used was computed tomography [n = 50 (70%)], followed by ultrasound [n = 24 (34%)]. Positron emission tomography [n = 10 (14%)] and magnetic resonance imaging [n = 8 (11.3%)] were used least. Eleven (2.6%) of the AJCC T1 tumours, five (1.4%) of the BWH T1 tumours, 22 (12.6%) of the BWH T2a tumours, 35 (26.5%) of the BWH T2b tumours, eight (7.6%) of the AJCC T2 tumours, four (66.7%) of the BWH T3 tumours, 47 (29.6%) of the AJCC T3 tumours and 0 (0%) of the AJCC T4a tumours were imaged. Twelve (17%) had a positive finding on imaging that altered the management plan, including local invasion [n = 4 (33%)], atypical lymph node [n = 4 (33.3%)], metastasis [n = 3 (25%)] and perineural invasion [n = 1 (8.3%)]. Of these, the majority were BWH T2b [n = 8 (67%)] and AJCC T3 [n = 11 (91.7%)]. This study demonstrates the utility of radiology imaging in addition to the current staging systems in identifying patients with cSCC at risk of poor outcomes.