Extensive perineural invasion may be optimal prognostic measure for poor CSCC outcomes

Key takeaways:

• Only the involvement of five or more distinct nerves was associated with poor patient outcomes.
• Poor outcomes included local recurrence, disease-specific death and any poor outcome.

Extensive perineural invasion may be the optimal prognostic measure of perineural invasion and poor cutaneous squamous cell carcinoma outcomes, according to a study.

“Perineural invasion (PNI) ... is a well-recognized poor prognostic feature in cutaneous squamous cell carcinoma (CSCC) and a risk factor in both the Brigham and Women’s Hospital (BWH) and the American Joint Committee on Cancer staging systems,” Paul R. Massey, MD, MPH, of the Cheyenne Skin Clinic in Cheyenne, Wyoming, and colleagues wrote. “Despite recognition of the importance of PNI in the prognosis and management of CSCC, limited research has comprehensively compared different methods of measuring and quantifying PNI with regard to prognostic prediction.”

Researchers conducted a retrospective cohort study of 140 patients (mean age, 75.1 years; 66.4% men; 94.3% white) with CSCC to evaluate patient outcomes of four PNI assessments: nerve caliber, number of involved nerves per section, PNI maximal depth and PNI location with respect to tumor.

Results showed that only the involvement of five or more distinct nerves, also called extensive PNI (ePNI), was independently associated with poor patient outcomes including local recurrence (subhazard ratio [SHR] = 13.83; 95% CI, 3.5-54.62), disease-specific death (SHR = 6.2; 95% CI, 1.59-24.21) and any poor outcome (SHR = 10.21; 95% CI, 2.88-36.15).

Substituting ePNI for large-caliber PNI (lcPNI) as a risk factor in the BWH staging system improved the area under the curve (69%; 95% CI, 56.2%-81.7%) compared with the current BWH staging criteria (58.5%; 95% CI, 46.8%-70.2%), which used nerve caliber as the measure for PNI, and compared with a staging model that allowed either ePNI or lcPNI (64.4%; 95% CI, 53.2%-75.7%).

The substitution of ePNI also improved the specificity (0.682; 95% CI, 0.6-0.764), positive predictive values (0.204; 95% CI, 0.133-0.276) and negative predictive values (0.949; 95% CI, 0.911-0.988) of the BWH staging system.

“Although these findings require further validation in other cohorts, inclusion of ePNI as a high-risk factor in CSCC staging may optimize recurrence risk assessment and patient selection for surgical treatment modality and postoperative adjuvant interventions,” the authors concluded.