Aim: To provide an update on current recommendations for management of cutaneous squamous cell carcinoma with perineural invasion (cSCCwPNI), including which cases may benefit from adjuvant radiation (ART), and present data from the Queensland PNI group’s retrospective analysis of cSCCwPNI from the years 2009 to 2017.
Methods: We conducted a retrospective analysis, in collaboration with Cancer Alliance Queensland (CAQ), of patients in Queensland histologically diagnosed with primary cSCCwPNI between 2009-2017. Patients were identified through Queensland Oncology Repository, managed by CAQ, which identifies all patients diagnosed with keratinocyte cancers from Queensland-based public hospitals via a linked pathology provider. Patient demographics, tumour and nerve-specific factors, and radiotherapy utilisation were reviewed.
Results: 558 cSCCwPNI were identified between 2009-2017. cSCCwPNI mostly affected males (n=449; 80.47%). 187 (33.51%) cases had margin involvement, 72 (38.50%) were re-excised with 52 (72.22%) achieving clearance. Of these 18 (34.62%) had ART with 6 (33.33%) recurrences and 2 (11.11%) metastases; those managed without ART had 3 (9.09%) recurrences and 0 metastases. Of the 14 (19.44%) without margin clearance, all had ART with 4 (28.57%) recurrences and 1 (7.14%) metastasis.
PNI confers increased risk of recurrence, lymphatic spread, metastasis and decreased overall survival. Lack of appropriate guidelines for management of cSCCwPNI stems from a paucity of data regarding nerve-specific factors. A recent prospective study and systematic review highlight the importance of Mohs micrographic surgery in high-risk cSCCs and use of ART in cases with PNI >0.1mm.
Conclusion: Further tumour and nerve-specific analyses are required to delineate which cases benefit from ART.