, according to new findings.
In addition, regardless of the NCCN risk group, the study found that Mohs surgery or peripheral and deep en face margin assessment (PDEMA) conferred a lower risk of developing LR, DM, and disease-related death.
“Although the NCCN included this new high-risk group in the last iteration of the guidelines, there were no studies that identified whether the high-risk group achieved the goal of identifying riskier tumors,” said senior author Emily Ruiz, MD, MPH, associate physician at the Mohs and Dermatologic Surgery Center at Brigham and Women’s Faulkner Hospital, Boston. “Based on the data in our study, the risk groups did risk stratify tumors and so clinicians can utilize the high-risk group risk factors to identify which tumors may require additional surveillance or treatment.”
The study was published online in JAMA Dermatology.
Most patients with CSCC are successfully treated with Mohs micrographic surgery or wide local excision (WLE) alone, but a subset will experience more severe and aggressive disease. While useful for prognostication, current staging systems do not incorporate patient factors or other high-risk tumor features that influence outcomes, which led to the NCCN reclassifying CSCC into low-, high-, and very high-risk groups. The NCCN guidelines also made a new recommendation that Mohs or PDEMA be the preferred method for tissue processing for high- and very-high-risk tumors, based on this new stratification.
However, these changes to the NCCN guidelines have not been validated. The goal of this study was to compare outcomes in very-high-, high-, and low-risk NCCN groups as well as comparing outcomes of CSCCs stratified by Mohs and WLE.
Dr. Ruiz and colleagues conducted a retrospective cohort study using patient data from two tertiary care academic medical centers. Their analysis included 10,196 tumors from 8,727 patients that were then stratified into low-risk (3,054 tumors [30.0%]), high-risk (6,269 tumors [61.5%]), and very-high-risk (873 tumors [8.6%]) groups.
Tumors in the very-high-risk group were more likely to have high-risk tumor and histologic features, such as large-caliber perineural invasion, large diameter, invasion beyond the subcutaneous fat or bone, poor differentiation, and lymphovascular invasion.
The authors found that, compared with the low-risk group, the high- and very-high-risk groups demonstrated a greater risk of LR (high-risk subhazard ratio, 1.99; P = .007; very-high-risk SHR, 12.66; P < .001); NM (high-risk SHR, 4.26; P = .02; very-high-risk SHR, 62.98; P < .001); DM (high-risk SHR, 2.2 × 107; P < .001; very-high-risk SHR, 6.3 × 108; P < .001); and DSD (high-risk SHR, 4.02; P = .03; very-high-risk SHR, 93.87; P < .001).
Adjusted 5-year cumulative incidence was also significantly higher in very-high- vs. high- and low-risk groups for all endpoints.
They next compared the procedures used to treat the tumors. Compared with WLE, patients treated with Mohs or PDEMA had a lower risk of LR (SHR, 0.65; P = .009), DM (SHR, 0.38; P = .02), and DSD (SHR, 0.55; P = .006).
Mohs and PDEMA have already became preferred surgical modalities for high- and very-high-risk tumors, and Dr. Ruiz pointed out that their analysis was for the entire cohort.
“We did not stratify this by risk group,” she said. “So our results do not change anything clinically at this time, but support prior studies that have found Mohs/PDEMA to have improved outcomes, compared to WLE. Further studies are needed evaluating surgical approach by risk-group.”
However, she emphasized, “our studies further validate prior evidence showing Mohs/PDEMA to have the lowest rates of recurrence and in this study, even disease-related death.”
Approached for an independent comment, Jeffrey M. Farma, MD, codirector of the melanoma and skin cancer program, and interim chair, department of surgical oncology, Fox Chase Cancer Center, Philadelphia, noted that this study supports the new reclassification of CSCC tumors by the NCCN, and confirms that the high-risk and very-high-risk tumors surely have a higher propensity for worse outcomes overall.
“That being said, the notion for type of resection and margin assessment is still an area of controversy in the dermatology, surgical oncology, and pathology community,” said Dr. Farma, who is also on the NCCN panel. “I believe we need further studies to truly understand the role of the type of resection and the pathologic evaluation play in this disease process.”
He also pointed out that it is unclear in this dataset if patients initially had any imaging to evaluate for local or regional metastatic disease. “It would be helpful to have a further understanding of which type of provider was performing the excisions, the type of excision decided upon, and if there was a standardized approach to [decide] which patients had MOHS or PDEMA and what was the surveillance for these patients both with imaging and physical examinations,” said Dr. Farma. “This data also evaluated patients over a long time period where practice patterns have evolved.”
Finally, he noted that the number of local and metastatic events subjectively seems low in this cohort. “We also do not know any information about the initial workup of the patients, patterns of recurrence, and adjuvant or palliative treatment after recurrence,” he added. “It is unclear from this manuscript how the type of resection or pathologic evaluation of margins leads to improved outcomes and further prospective studies are warranted.”
Dr. Ruiz reports reported serving as a coinvestigator and principal investigator for Regeneron Pharmaceuticals and as a coinvestigator for Merck and consulting for Checkpoint Therapeutics, BDO, and Genentech outside the submitted work. Dr. Farma has no disclosures other than the NCCN panel. The study was supported by Harvard Catalyst and the Harvard University Clinical and Translational Science Center and by Harvard University and its affiliated academic health care centers and partially supported by the Melvin Markey Discovery Fund at Cleveland Clinic Foundation.