Method of Assessing Skin Cancerization and KeratosesTM (MASCK™): development and photographic validation in multiple anatomical sites of a novel assessment tool intended for clinical evaluation of patients with extensive skin field cancerization.

BACKGROUND: A range of 'field-directed' treatments is available for the management of extensive skin field cancerization (ESFC), but to date, the only validated objective quantitative tools are limited to assessment of actinic keratoses (AKs) affecting the head. AIMS: 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 noninterventional and used a convenience sample of de-identified patient photographs selected based on preset 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 chance-corrected agreement coefficients (ACs). RESULTS: The instrument produced, called the Method for Assessing Skin Cancer and Keratoses™ (MASCK™), comprises the Skin Field Cancerization Index (SFCIndex), derived from area of skin involvement and AKs (number and thickness), a global assessment score and a cancer-in-zone score, and uses Likert scales for quantitative scoring. The SFCIndex is a composite score comprising the number and thickness of AKs multiplied by area of skin involvement. ACs for the SFCIndex components, the overall SFCIndex score and the global assessment score were > 0.80 (rated 'almost perfect') while the AC for the 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.

A review of actinic keratosis, skin field cancerisation and the efficacy of topical therapies.

While a wide range of treatments exist for actinic keratosis and skin field cancerisation, the long-term benefits of the most common topical therapies are poorly defined. This report reviews the efficacy of the most commonly used topical therapies to treat regional or field lesions. Limited clinical and histopathological data are available on clearance rates at 12 months post-treatment for the most commonly used agents, with varied outcome measures making any comparison difficult. In general, total field clearance rates at 12 months are suboptimal for the most commonly employed agents. Given the increasing incidence of actinic keratosis and skin field cancerisation due to an ageing population, further research into the efficacy of therapies is critical to guide treatment choice.

Radiotherapy, Utilizing Volumetric Modulated Arc Therapy, for Extensive Skin Field Cancerization: A Retrospective Case Series Assessing Efficacy, Safety, and Cosmetic Outcomes at 12 Months After Treatment.

Extensive Skin Field Cancerization (ESFC) describes multiple actinic keratoses, with and without keratinocyte skin cancers. These areas are characterised by dysplastic keratoses, are prone to new malignancies, involve significant morbidity, have a poor cosmetic appearance, and impact negatively on quality of life. Available topical field therapies have limited durability of efficacy. Volumetric modulated arc therapy (VMAT) is an advanced form of intensity-modulated radiotherapy which achieves highly modulated and conformal dosimetry, delivering a homogeneous dose, particularly over curved surfaces, for example, scalps and limbs. This series describes the 12-month follow-up analysis of 41 VMAT treated fields from 32 (21 M, 11 F) patients. Consent was obtained after VMAT treatment to allow access to outcomes data. Conditions treated include ESFC, Bowen's disease/SCC in situ, cutaneous squamous cell carcinoma, and basal cell carcinoma (BCC). Efficacy was measured by the percentage reduction of visible pathology within the treatment field. The primary endpoint for this review was the assessment of treatment success, defined as >90% clearance of the treatment field. As part of this definition, the appearance of isolated keratoses at 12 months was considered not significant if the field overall was clear. The development of new or recurrent cancers within the 12-month follow-up period was recorded. Thirty-six fields (87%) achieved a clinical clearance >90%. Of those, 33 (80%) fields achieved complete clearance >99% of visible actinic keratosis or keratinocyte cancers. Three fields (7%) demonstrated 91-99% clinical clearance, and no treatment failures were recorded. Two newly occurring lesions (1 BCC and 1 SCC in situ) were identified within a treated field at 12 months. The reported toxicities at 12-month post-treatment were grade 1 or 2 only, with no cases of persistent radiation dermatitis. Toxicities reported in more than 5% of cases included: alopecia (n = 4); dryness (n= 3); erythema (n = 2); and telangiectasia ulceration (n = 4). The high rate of complete clearance at 12 months seen in this case series compares very favourably with other treatments, including topical 5-fluorouracil, imiquimod, and photodynamic therapy. Toxicities reported in our patient population demonstrated that VMAT was well tolerated at 12-month post-treatment. VMAT treatment may play a growing role in future therapy for ESFC with and without keratinocyte cancers.