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

Abstract

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 (<i>n</i> = 4); dryness (<i>n</i>= 3); erythema (<i>n</i> = 2); and telangiectasia ulceration (<i>n</i> = 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.

Porokeratoses—A Comprehensive Review on the Genetics and Metabolomics, Imaging Methods and Management of Common Clinical Variants

“…A single report on the use of high-dose-rate iridium-192 brachytherapy in one DSAP patient shows that this method can also be useful in selected limited areas and well tolerated [131]. However, clinicians should be aware of the long-term side effects of the different forms of radiotherapy, including pigmentation disorders, alopecia, skin atrophy, telangiectasia, fibrosis and secondary skin malignancies [17,128,132]. On the other hand, radiotherapy might be employed to treat DSAP with concomitant skin malignancy or even skin field cancerisation.…”

Efficacy and safety analysis: 24‐month outcomes from a prospective cohort of 106 fields treated with widefield radiation therapy for extensive skin field cancerization, with or without keratinocyte cancers

“…1,4,5 Extensive skin field cancerization (ESFC) is a new concept without a clear definition but refers to particularly broad, contiguous areas of disease involvement, generally ≥50 cm 2 , or an entire anatomic unit of skin. 6 Patients often have a history of multiple field therapies, high keratinocyte cancer (KC) burden [7][8][9][10][11] and poor quality of life (QoL). 12 In addition to AK clearance, another goal of field treatment is to prevent new KC development.…”

Wide‐field radiation therapy for skin cancerisation – Have we forgotten what we learned?

“…Factors which significantly increase the risk of severe acute reactions and possible consequential late reactions have been acknowledged in published experience of cohorts treated with VMAT for SFC, and treatment recommendations have evolved to reduce the risks. [8][9][10][11][12] The increased risk with treatment of the lower leg for example, especially where the vasculature is poor, has been acknowledged. The dose being delivered has been lowered and a two-week break has been recommended for those at higher risk of severe acute reactions.…”

“…These reports have significant limitations including unblinded outcome assessment and relatively short-term follow-up of up to 12 months. [8][9][10][11][12] While 12 -month follow up is acceptable for topical treatments for AK, the fact that RT treats the entire thickness of skin and permanently alters the integrity makes long-term follow-up and outcome assessment essential. Longer follow-up is essential for documenting not only efficacy but the late consequences of any course of RT that may significantly impact well-being and quality of life.…”

“…Evidence published to date is limited to the experience of single organisations or ROs. These reports have significant limitations including unblinded outcome assessment and relatively short‐term follow‐up of up to 12 months 8–12 . While 12 ‐month follow up is acceptable for topical treatments for AK, the fact that RT treats the entire thickness of skin and permanently alters the integrity makes long‐term follow‐up and outcome assessment essential.…”