Squamous cell carcinoma antigen (SCCA) is a biomarker of disease progression in squamous cell carcinoma but also contributes to the pathogenesis of psoriasis. Eight previous studies have shown a correlation between psoriasis severity, assessed using the Psoriasis Assessment Severity Index or body surface area, and serum level of SCCA, mainly SCCA2, assessed by means of non-commercial tests. We examined the correlation between serum SCCA level, measured with a commercial kit, and psoriasis severity assessed using the Simplified Psoriasis Index (SPI).

We conducted a prospective, non-interventional, single-centre study at the University Hospital of Tours over 18 months. The primary endpoint was same-day measurement of serum SCCA level and the psoriasis severity score on the professional version of the SPI (proSPI-s) at both baseline and follow-up. Secondary endpoints were same-day measurement of serum SCCA level and the proSPI psychosocial score (proSPI-p), proSPI treatment score, Dermatology Life Quality Index (DLQI), and inflammation parameters (C-reactive protein level, neutrophil-to-lymphocyte ratio).

We included 50 psoriasis patients. Serum SCCA level was correlated with the proSPI-s at baseline and follow-up (Spearman r = 0.686 and r = 0.674, p < 0.0001) for both. It was correlated with the proSPI-p and DLQI. Serum SCCA level was not correlated with either neutrophil-to-lymphocyte ratio (r = 0.083) or C-reactive protein level (r = 0.192).

This study is the first to correlate serum SCCA level with proSPI-s. Moreover, SCCA was measured using a widely available kit. SCCA may be used to assess the severity of psoriasis.