Top Line: All perineural invasion (PNI) is not created equal.
The Study: NCCN guidelines currently recommend consideration of adjuvant radiation for cutaneous squamous cell carcinoma with PNI that is extensive, large caliber, or involving named nerves. A retrospective investigation of 140 patients with cSCC with PNI compared four varying ways to define high-risk PNI: involved nerve caliber (< or ≥0.1 mm), number of involved nerves per section (1, 2-4, or ≥5), deepest involved histologic level (dermis, fat, muscle, fascia, etc), and location with respect to tumor (intratumoral, peripheral, or discontinuous). In this cohort, perineural invasion of ≥5 distinct nerves in a single section (i.e., extensive PNI) was the only independent predictor of local recurrence (HR 13.83) and disease-specific death (HR 6.20). Most interestingly, replacing large-caliber PNI with extensive PNI in the Brigham and Women’s Hospital staging system resulted in an improved area under the curve with 36 tumors downstaged and 0 upstaged. Another positive note is recording the number of nerves involved is technically much easier than measuring extent to the micrometer.
TBL: “Inclusion of extensive PNI as a high-risk factor in CSCC staging may optimize recurrence risk assessment and patient selection for surgical treatment modality and postoperative adjuvant interventions.” | Massey, JAMA Dermatol 2023
The Study: NCCN guidelines currently recommend consideration of adjuvant radiation for cutaneous squamous cell carcinoma with PNI that is extensive, large caliber, or involving named nerves. A retrospective investigation of 140 patients with cSCC with PNI compared four varying ways to define high-risk PNI: involved nerve caliber (< or ≥0.1 mm), number of involved nerves per section (1, 2-4, or ≥5), deepest involved histologic level (dermis, fat, muscle, fascia, etc), and location with respect to tumor (intratumoral, peripheral, or discontinuous). In this cohort, perineural invasion of ≥5 distinct nerves in a single section (i.e., extensive PNI) was the only independent predictor of local recurrence (HR 13.83) and disease-specific death (HR 6.20). Most interestingly, replacing large-caliber PNI with extensive PNI in the Brigham and Women’s Hospital staging system resulted in an improved area under the curve with 36 tumors downstaged and 0 upstaged. Another positive note is recording the number of nerves involved is technically much easier than measuring extent to the micrometer.
TBL: “Inclusion of extensive PNI as a high-risk factor in CSCC staging may optimize recurrence risk assessment and patient selection for surgical treatment modality and postoperative adjuvant interventions.” | Massey, JAMA Dermatol 2023