Prognostic value of inositol polyphosphate-5-phosphatase expression in recurrent and metastatic cutaneous squamous cell carcinoma

Inositol polyphosphate-5-phosphatase (INPP5A) has been shown to play a role in the progression of actinic keratosis to cutaneous squamous cell carcinoma (cSCC) and the progression of localized disease to metastatic disease. Currently, no cSCC biomarkers are able to risk stratify recurrent and metastatic disease. To determine the prognostic value of INPP5A expression in cSCC recurrent and metastatic disease. We conducted a multicenter, single-institutional, retrospective cohort study within the Mayo Clinic Health System on the use of immunohistochemical staining to examine cSCC INPP5A protein expression in primary tumors and recurrent and metastatic disease. Dermatologists and dermatopathologists were blinded to outcome. Low staining expression of INPP5A in recurrent and metastatic disease tumors was associated with poor overall survival (OS) (31.0 months for low versus 62.0 months for high expression; P = .0272). A composite risk score (calculated as score of primary tumor + score of recurrent or metastatic disease tumor, with tumors with high expression scoring a zero and low expression a 1, score range 0-2) of 0 was predictive of improved OS compared with a composite risk score of ≥1 (hazard ratio 0.42, 95% confidence interval 0.21-0.84; P = .0113). This is a multicenter but single institution study of a white population. Loss of INPP5A expression predicts poor OS in recurrent and metastatic disease of cSCC.