LAUSR

BACKGROUND A range of 'field-directed' treatments are available for the management of extensive skin field cancerisation (ESFC), but to date the only validated objective quantitative tools are limited to assessment of actinic keratoses (AK) affecting the head. OBJECTIVES To develop a versatile quantitative instrument for objective clinical assessment of ESFC and perform initial internal validation across multiple anatomical zones. METHODS The study comprised instrument development, pilot testing and instrument refinement, and two rounds of reliability and inter-rater validation testing. The study was non-interventional and utilized a convenience sample of de-identified patient photographs selected based on pre-set criteria. An expert panel developed the instrument and scoring system via a modified Delphi voting process. A sample of 16 healthcare professionals from multiple specialties undertook the pilot testing and a panel of seven dermatologists were involved in validation testing. Validation was determined by assessment of overall inter-rater agreement using Gwet's chance-corrected agreement coefficients (AC). RESULTS The Method for Assessing Skin Cancer and Keratoses (MASCKTM ) comprises a skin field cancerisation index (SFCIndex), derived from area of skin involvement and actinic keratosis (number and thickness), a global assessment score, and a cancer-in-zone score and utilizes Likert-scales for quantitative scoring. The SFCIndex is a composite score comprising the number and thickness of AK multiplied by area of involvement. ACs for the SCFIndex components, the overall SFCIndex score and the global assessment score were >0.80 (rated 'almost perfect'); the AC for cancer-in-zone metric was lower (0.33 , rated 'fair') Internal consistency was demonstrated via positive correlation between the overall SFCIndex score and the global assessment score. CONCLUSIONS Our study found near perfect agreement in inter-rater reliability when using MASCK to assess the severity of ESFC in multiple anatomical sites. Further validation of this novel instrument is planned to specifically assess its reliability, utility and feasibility in clinical practice.