A Comment on “Effectiveness and Patient Experiences of Rhenium Skin Cancer Therapy for Nonmelanoma Skin Cancer: Interim Results from the EPIC-Skin Study”

TO THE EDITOR: We read with interest the article entitled, “Effectiveness and Patient Experiences of Rhenium Skin Cancer Therapy for Nonmelanoma Skin Cancer: Interim Results from the EPIC-Skin Study” by Baxi et al. (1)

The abstract claims that this study “indicates that [rhenium skin cancer therapy] is safe and effective for the treatment of BCC and SCC and is associated with significant [quality-of-life] improvements” (1).

The most cursory examination of the data relied on shows that this claim is impossible to justify. The study is unmasked, with no control group. Fewer than 50% of the treated lesions were available for review. Even so, a 6-mo follow-up tells us little about efficacy. It is generally accepted that 5-y follow-up is required to document treatment efficacy. With no reliable measure of efficacy, how can safety be documented? Radiation side effects typically evolve over decades rather than months, so any claims regarding cosmesis or side effects are generally unreliable at 6-mo review.

The abstract adds, “Improvements in [quality of life] were also reported, whereas no patients reported any pain or discomfort during treatment” (1). What was this improvement measured against? Surely this claim could be made only if there was a control group. Once again, this assessment is completely compromised when only a minority of patients was available for review.

Worryingly, the trial is designed to follow treated patients for only 2 y. This is too short a period to accurately measure cure rates. Radiation side effects are known to persist and worsen well beyond this time. The authors state, “Long-term follow-up is required for this cohort, however, to assess the duration of response” (1). We would agree but wonder why they ignored their own advice when designing this study.

It is unclear whether enrolled patients were reviewed by a specialist surgeon before their lesions were deemed inoperable. A complete response rate of 97.2% is claimed, yet only 81 of 182 patients were available for review. This figure cannot be calculated from the data available. In an era of evidence-based medicine, it is misleading in the extreme to make this claim.

When deciding on optimal treatment of basal cell carcinoma, it is crucial to know the histopathologic subtype. This factor is not mentioned at all in the paper, severely limiting utility. How is the reader to use this publication when this crucial piece of information is missing?

The authors compare their paper with an article by Delishaj et al. (2) Such a comparison is incongruous because that paper excluded studies for which long follow-up times were not available. Moreover, Delishaj et al. used a much more aggressive treatment regime.

Perusal of the available literature on rhenium skin cancer therapy reveals common factors. As here, many if not most treated patients are not available for review. Follow-up times are less than 5 y. Control groups are lacking, and significant detail such as basal cell carcinoma subtype are missing.

To us, it seems extraordinary that this unproven treatment is being actively marketed outside well-designed, controlled trials.

• © 2025 by the Society of Nuclear Medicine and Molecular Imaging.

• Received for publication October 31, 2024.
• Accepted for publication November 4, 2024.