For the effective treatment of psoriasis, it is necessary to assess disease activity properly. The assessment is usually carried out through the estimation of the psoriasis area and severity index (PASI)1 with consideration of additional findings, such as pustules, itching, and arthralgia. The PASI score, however, cannot be truly quantitative or provide an absolute numerical value, setting a limit to the collation and analysis of research from diverse international sources. Moreover, the PASI is too complex to apply to many patients clinically. Therefore, the development of a new method of psoriasis assessment has long been desired.
The squamous cell carcinoma (SCC) antigen was first identified by Kato and Torigoe2 as a tumor-associated antigen from human uterine cervical SCC tissue. To make it possible to detect the antigen activity in the serum of patients with SCC of the cervix, a double antibody radioimmunoassay has been developed. Several studies3
Hamanaka S, Ujihara M, Numa F, Kato H. Serum Level of Squamous Cell Carcinoma Antigen as a New Indicator of Disease Activity in Patients With Psoriasis. Arch Dermatol. 1997;133(3):393-395. doi:10.1001/archderm.1997.03890390137030