Response to Radiotherapy in Basal Cell Carcinoma: Comparison of Noninvasive Imaging Modalities
Posted: Wednesday, October 21, 2020
Noninvasive imaging modalities such as dermoscopy, high-frequency ultrasonography, and reflectance confocal microscopy were used to characterize the in vivo effects of radiotherapy for patients with basal cell carcinoma. In the Journal of the American Academy of Dermatology, Christopher A. Barker, MD, of Memorial Sloan Kettering Cancer Center, New York, and colleagues reported that dermoscopy and high-frequency ultrasonography were not as reliable in assessing response to radiotherapy in these patients as reflectance confocal microscopy.
“In this prospective, preliminary study, we performed 137 independent imaging assessments and observed that reflectance confocal microscopy could possibly enable evaluation of the pathophysiologic effects of high-dose ionizing radiation in the skin, without the need for disruption of skin architecture with repeated biopsies,” the investigators commented.
The three modalities were performed prior to treatment and at post-radiation intervals of 6 weeks, 3 months, and 12 months. A total of 12 patients with biopsy-positive basal cell carcinoma were treated with 6 fractions of 7 Gy, for a total dose of 42 Gy. The mean patient age at diagnosis was 77 years, and the mean follow-up was 31.7 months.
Dermoscopy was not significantly indicative of response to radiotherapy, although there was evidence of an “orange color” and peppering; the study authors attributed these findings as likely plump cells, inflammatory cells, and epidermal dendritic cells. However, there were clinically significant findings with reflectance confocal microscopy. Evidence of palisading, a positive feature for basal cell carcinoma, decreased from baseline levels of 91.7% to 8.3% at 12-month follow up. Clefting, another positive indicator, decreased from 75.0% at baseline to 8.3% at 12-month follow-up.
Histologic confirmatory evidence of radiotherapy via biopsies was not obtained, as no patient presented with clinically evident recurrent disease after a mean follow-up of 31.7 months. Additional study limitations included a small sample size and lack of a control group.
Disclosure: For full disclosures of the study authors, visit jaad.org.