Local Control Comparison of Early-Stage Epidermal Skin Cancers Treated With and Without Dermal Image Guidance: A Meta-Analysis

Abstract

Background: Various treatments exist for non-melanoma skin cancer (NMSC), but the mainstay is surgical removal. Superficial radiotherapy (SRT) is one non-surgical technique that has been used for over a century but fell out of favor due to the advent of Mohs micrographic surgery (MMS). A new technology that combines a 22 megahertz (MHz) dermal ultrasound with SRT (US-SRT) enables tumor visualization before, during, and after treatment, and demonstrates increased cure rates and reduced recurrences. Methods: We conducted a meta-analysis comparing the local control (LC) of four traditional non-image-guided forms of radiotherapy for NMSC treatment to two seminal studies utilizing high-resolution dermal ultrasound-guided SRT (HRUS-SRT). The four traditional radiotherapy studies were obtained from a comprehensive literature search used in an article published by the American Society of Radiation Oncology (ASTRO) on curative radiation treatment of basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and squamous cell carcinoma in-situ (SCCIS) lesions. The meta-analysis employed a logit as the effect size indicator with Q-statistic to test the null hypothesis. Results: LC rates for the 2 US-SRT studies were statistically superior to the 4 traditional therapies individually and collectively. When stratified by histology, statistically superior outcomes for US-SRT were observed in all subtypes with p-values ranging from p < 0.0001 to p = 0.0438. These results validated an earlier analysis using a logistic regression statistical method showing the same results. Conclusion: US-SRT is statistically superior to non-image-guided radiotherapies for NMSC treatment. This modality may represent the future standard of non-surgical treatment for early-stage NMSC.

Radiation sensitivity and efficacy in aggressive and non-aggressive basal cell carcinoma (BCC) of the skin: Image Guided Superficial Radiation Therapy achieves high rate of local control in sclerosing, infiltrative, morpheaform and micronodular BCC subtypes as well as in non high risk BCCs, an analysis of 7994 BCC lesions

“…The most obvious explanation for this improvement is the new ability of IGSRT over tradiational non-image guided radiotherapy modalities. In 2 recent studies using logistic-regression analysis and meta-analysis, LC in the treatment of NMSC using IGSRT in comparison to non-image guided external radiation modalities (superficial radiation therapy (SRT) or external beam radiation therapy (XRT including electron beam or photon beam radiotherapy) have been shown to be superior and achieving statistically improved LC [14,15] and were attributed to the image guidance factor. Whereas previously, the use of RT may not have been recommended for high risk BCCs due to potentially higher recurrence rates, the advent of HRDUS in combination with SRT allow more precision to be directed to the full depth of the tumor and ushers in an era of modern more exacting targeting of radiation beams that appears to be associated with higher success rates rivaling that of surgical interventions such as MMS and present a valuable treatment option especially for those who are not ideal candidates for surgical management.…”

“…As radiation therapy techniques have advanced recently, the introduction of image-guided superficial radiation therapy (IGSRT) which is a combination of HRDUS with SRT has allowed for the reconsideration of methods employed on treating skin cancer. Specifically, with regard to early stage NMSC (including high risk BCCs), IGSRT, which is regarded as precision and targeted medicine, potentially mitigates limitations associated with conventional non image-guided traditional radiation therapy (such a external/electron beam radiotherapy [XRT] and superficial radiation therapy [SRT]) and has been shown to statistically improve outcomes on treatment of all major histologies of NMSC, such as BCC, SCC and SCCIS [12][13][14][15]. On this basis, it stands to reason that re-assessment of the previous notion of bypassing the option of radiotherapy in high risk subtypes of BCCs should be evaluated using this more modern method of radiotherapy incorporating image guidance intrinsically to assess to see if the prevailing sentiment of non-radiation approach still holds true.…”