PHOENIX – .
“For 2,000 years, it’s been known that heat can kill cancers,” an apoptotic reaction “rather than a destructive reaction coming from excessive heat,” Christopher B. Zachary, MD, said at the annual conference of the American Society for Laser Medicine and Surgery, where the study was presented during an abstract session.
Dr. Christopher B. Zachary
Dr. Zachary, professor and chair emeritus of the department of dermatology at the University of California, Irvine, and colleagues, evaluated a novel, noninvasive technique of controlled hyperthermia and mapping protocol (CHAMP) designed to help clinicians with margin assessment and treatment of superficial and nodular BCCs. For this prospective study, which was first described at the 2022 ASLMS annual conference and is being conducted at three centers, 73 patients with biopsy-proven superficial and nodular BCCs have been scanned with the VivoSight Dx optical coherence tomography (OCT) device to map BCC tumor margins.
The BCCs were treated with the Sciton 1,064-nm Er:YAG laser equipped with a 4-mm beam diameter scan pattern with no overlap and an 8-millisecond pulse duration, randomized to either standard 120-140 J/cm2 pulses until tissue graying and contraction was observed, or the CHAMP controlled hyperthermia technique using repeated 25 J/cm2 pulses under thermal camera imaging to maintain a consistent temperature of 55º C for 60 seconds. Patients were rescanned by OCT at 3 to 12 months for any signs of residual tumor and if positive, were retreated. Finally, lesions were excised for evidence of histological clearance.
To date, 48 patients have completed the study. Among the 26 patients treated with the CHAMP method, 22 (84.6%) were histologically clear, as were 19 of the 22 (86.4%) in the standard treatment group. Ulceration was uncommon with the CHAMP method, and patients healed with modest erythema, Dr. Zachary said.
Pretreatment OCT mapping of BCCs indicated that tumors extended beyond their 5-mm clinical margins in 11 cases (15%). “This will be of interest to those who treat BCCs by Mohs or standard excision,” he said. Increased vascularity measured by dynamic OCT was noted in most CHAMP patients immediately after irradiation, which suggests that apoptosis was the primary mechanism of tumor response instead of vascular destruction.
“The traditional technique for using the long pulsed 1,064-nm Er:YAG laser to cause damage and destruction of BCC is 120-140 J/cm2 at one or two passes until you get to an endpoint of graying and contraction of tissue,” Dr. Zachary said. “That’s opposed to the ‘Low and Slow’ approach [where you use] multiple pulses at 25 J/cm2 until you achieve an optimal time and temperature. If you treat above 60º C, you tend to get epidermal blistering, prolonged healing, and interestingly, absence of pain. I think that’s because you kill off the nerve fibers. With the low fluence multiple scan technique, you’re going for an even flat-top heating.”
Currently, he and his colleagues consider 55 degrees at 60 seconds as “the optimal parameters,” he said, but “it could be 45 degrees at 90 seconds or two minutes. We don’t know yet.”
In an interview at the meeting, one of the abstract session moderators, Mathew M. Avram, MD, JD, director of laser, cosmetics, and dermatologic surgery at Massachusetts General Hospital, Boston, said that he was encouraged by the study results as investigations into effective, noninvasive treatment of BCC continue to move forward. “Details matter such as the temperature [of energy delivery] and noninvasive imaging to delineate the appropriate margins,” said Dr. Avram, who has conducted research on the 1,064-nm long-pulsed Nd:YAG laser as an alternative treatment for nonfacial BCCs in patients who are poor surgical candidates.
Dr. Mathew M. Avram
“Hopefully, at some point,” he said, such approaches will “become the standard of care for many BCCs that we are now treating surgically. I don’t think this will happen in the next 3 years, but I think in the long term, it will emerge as the treatment of choice.”
The study is being funded by Michelson Diagnostics. Sciton provided the long-pulsed 1,064-nm lasers devices being used in the trial. Dr. Zachary reported having no relevant disclosures. Dr. Avram disclosed that he has received consulting fees from Sciton.