Aaron Farberg, MD: Image Guided SRT Achieves High Cure Rates in Non Melanoma Skin Cancer

The Dermatology Association of Radiation Therapy recently published a large retrospective cohort study highlighting the effectiveness of image-guided superficial radiation Therapy (IGSRT) for treating non melanoma skin cancer.¹

The study, published in Geriatrics, involved nearly 20,000 NMSC lesions treated from 2016 to 2023. Researchers reported high freedom from recurrence rates of over 99% at 2, 4, and 6 years, demonstrating that IGSRT is a reliable treatment option across various patient demographics, including different age groups and sexes.

Dermatology Times recently spoke with Aaron Farberg, MD, a double board-certified dermatologist, a Mohs surgeon, chief medical officer at Bare Dermatology in Dallas, Texas, and Dermatology Times' spring editor in chief. Farberg, a study author, shared insights into the data and pearls for non melanoma skin cancer treatment.

Transcript

Aaron Farberg, MD: I'm Aaron Farberg, a double board-certified dermatologist and Mohs surgeon. I'm based in Dallas, Texas, and I'm in private practice with my office, Bare Dermatology, and am also affiliated and the Assistant Program Director for their Lake Granbury Medical Center dermatology residency, as well as the University of North Texas Health Science Center.

Dermatology Times: Can you summarize the key findings of your recent study on image-guided SRT for non melanoma skin cancer? What do these results suggest about the effectiveness of this treatment?

Farberg: We recently published a paper looking at the high freedom of recurrence rates that were discovered for treatment of non melanoma skin cancer, with image guided superficial radiation therapy. We looked at this across age and sex as well as staging, and we discovered that there was very high freedom of recurrence across the board. It didn't matter whether they were old, young, male, female, advanced stage or early stage. This is highly important, mostly because of the very large sample size, almost 20,000 reported lesions that were evaluated. This was both basal cell and squamous cell. Again, it really highlights the efficacy of this treatment; of course, as a Mohs surgeon, first and foremost, we often will utilize Mohs in treatment of non melanoma skin cancer lesions. But it's important for us to have a variety of treatment options, and one of them that has been around and developed by dermatologists over 100 years ago has been superficial radiation therapy.

Now, wide local excisions have been around for decades, too. We used to cut out cancer, and then we had the development of Mohs surgery, which was a huge advancement in our surgical abilities. Similarly, superficial radiation therapy has been around, and there's been a number of different protocols and ways of treating a variety of different lesions. More recently, there's been the establishment of these image guided protocols, which involves a number of office visits and also utilizes high resolution ultrasound, which then helps us determine the depth, and we can then better identify the exact treatment dose of radiation for these lesions. The next question is this: "Well, does this provide any sort of advantage over your standard superficial radiation therapy?" We need large sample sizes that are high quality in order to really answer this question, and this data begins to really elucidate exactly these results that we've been hoping for. Looking at that, high resolution image guided superficial radiation therapy does provide really very high efficacy. We're talking a 99% cure rate for non melanoma skin cancer.

Dermatology Times: The study reported low recurrence rates at 2, 4, and 6 years. How do these rates compare to traditional treatment methods like Mohs surgery?

Farberg: This study did not compare directly Mohs surgery and superficial radiation therapy, but we do consider Mohs to be a 99% cure rate. Now, I do believe that is quite operator dependent. It's also dependent on the type of lesions. Obviously, if you're part of a large academic center and you're seeing much more advanced skin cancers, it may not be 99%, and that's okay, too. Again, we all have been humbled by cancer. Having my training in plastic surgery amongst the surgical oncology department at the University of Michigan, we have been humbled many, many times, but it's good to see here that with image guided SRT, we're able to achieve the same 99% cure rates. Now, there's been a misunderstanding that perhaps superficial radiation therapy does not have as high of a cure rate. It's less than 99%, and perhaps that was true when you look at the previous literature and the previous data for non image guided SRT. Again, the scientific question is: "Is there an advantage of adding in the image guidance?" The only way to do that is a study like the one that we performed with a very or with a high quality retrospective data set that we can look back at and decide: "What were the outcomes?" Now, again, it's retrospective, so of course, there's limitations, but this is really some of the best data you could ever hope for. Importantly, there is a long follow-up here, up to 6 years for many of these lesions, so we can confidently say that when you do the correct image guided protocol, you're likely to have this high level of cure rate for both basal cell and squamous cell carcinoma across ages and across sex and staging, as well.

Dermatology Times: The research showed that recurrence rates did not vary by patient age or sex. What implications do these findings have for clinical practice in treating diverse patient populations?

Farberg: When we're looking at treating diverse patient populations, it's important to understand who is appropriate for superficial radiation therapy—more specifically, image guided superficial radiation therapy. That's the question we're hoping to answer. We did have a finding that older patients with more advanced disease, essentially stage 2, did have a slight increase risk of recurrence. Now thankfully, recurrence is not what drives our management. It's metastasis that we're worried about, and that will change what sort of management we would consider for these patients. But even still, with that slight increase of recurrence, it was still in the 99% freedom of recurrence range, so we're still doing a very good job with this treatment. What this is telling us is that we can consider image guided superficial radiation therapy, whether you're younger, older, male, female, or have stage 1, stage 2 disease, and we can confidently know that image guided superficial radiation therapy is going to have a very high efficacy rate into the 99 percentile, just as we would expect for Mohs surgery.

Dermatology Times: Could you discuss the safety profile of IGSRT based on your findings? How does it compare to other treatment modalities in terms of adverse effects and patient tolerance?

Farberg: When you compare SRT to other surgical interventions, all you have to do is ask the patient, and they'll all tell you that the advantage of superficial radiation therapy is that you don't have the same cutting surgery, recovery, scarring, that you get with Mohs or a wide local excision. It seems to be, in my clinical experience, bimodal interest in superficial radiation therapy. It happens around age 50 or 60, where you have patients that are a bit more cosmetically-driven and do not want to have scars. The reality is I trained with Shan Baker—the same Shan Baker that wrote the book that most most surgeons use to learn about facial reconstruction. When you look at those outcomes, even surgery on the nose and lips and ears, as good as they can be, they're still not perfect, and you still see scars. It's difficult to say to a 60 year old that, "Gosh, you're going to have this scar across your nose, and everyone, for the most part, is going to see it and know about it."

When I said a binomodal distribution of interest in SRT in the more advanced aged patient, notice, I didn't say elderly. The reality there is that many of these patients have had undergone multiple Mohs and wide local excisions. They've had numerous procedures, and they're getting tired of being cut on all the time, and they're desperate for alternative options. Again, this is where I think the discussion of image guided SRT is highly appropriate. I think it's appropriate across the board, mostly because we want to present our patients with all the options, and then we discuss the risks, the benefits, and the alternatives for all of these treatments, for all of our skin cancer patients.

Dermatology Times: What else should dermatology clinicians know or consider about this study?

Farberg: There's a long history of superficial radiation therapy in the field of dermatology, and we need to continue to progress this treatment, this therapy, for our patients. Thankfully, this is the next step: looking at the addition of image guided superficial radiation therapy, and it answers the very important question of: "Is there an advantage, and is there any difference, across patients, whether they're older, younger, male, female or have more advanced disease?" Importantly, we need to have high quality data and large data sets. In our study, we were able to show that image guided superficial radiation therapy does provide a very high efficacy rate across the board.

[Transcript has been edited for clarity.]

References

1. Study reports consistent high freedom from recurrence rates for nonmelanoma skin cancer treated with image-guided SRT regardless of age or sex. News release. PR Newswire. September 13, 2024. Accessed September 23, 2024. https://www.prnewswire.com/news-releases/study-reports-consistent-high-freedom-from-recurrence-rates-for-nonmelanoma-skin-cancer-treated-with-image-guided-srt-regardless-of-age-or-sex-302247315.html