AUSTIN — A novel pragmatic classification system (PCS) that considers resectability and high-stage tumors may be a more clinically useful staging paradigm for advanced cutaneous squamous cell carcinoma (cSCC) than relying solely on the current standard, according to research presented at the American College of Mohs Surgery (ACMS) Annual Meeting 2026. 

“Ideally, a good staging system helps guide treatment, prognosticate risk, stratifying and standardized communication for things such as clinical trials,” Freddy Gibson, MD, a clinical fellow in dermatology at Brigham and Women’s Hospital in Boston, told attendees while presenting his research. But then he showed a series of images that illustrated some of the issues with the American Joint Committee on Cancer 8^th edition (AJCC8) system, currently the most commonly used tumor-nodes-metastasis (TNM) system for staging cSCC. 

“Depending on what photo you're looking at here, you would probably assign them a different prognosis, and you probably would be thinking about different treatments for all of these patients, but these are all stage III,” Gibson said. “The problem with AJCC8 is that it doesn’t capture the spectrum of advanced cSCC.” 

For one, stages III and IV are heterogeneous, with both including resectable T3, nodal, unresectable, and distantly metastatic tumors. Also, the AJCC8 system excludes in-transit metastasis and tumors outside the head and neck, and the staging criteria lack prognostic distinctiveness, he said.

“Can we do better than AJCC8 with a system that reflects how we think and talk about advanced cSCC?” he said. That thought process typically involves first assessing whether a tumor is resectable or unresectable. Unresectable tumors lead to palliative care while resectable tumors are further divided into high-stage and locally advanced ones. Mohs surgery is indicated for high stage tumors whereas locally advanced tumors are more likely to require consideration with a multidisciplinary tumor board consideration, possibly involving neoadjuvant immunotherapy. 

Gibson described the proposed PCS with the following three categories: 

• High stage tumors, which are the routinely resectable AJCC8 T3 tumors that are treated with surgery and may be considered for adjuvant radiation therapy
• Resectable tumors that are locally advanced or regionally metastatic, where surgical removal is feasible, but where multidisciplinary planning and/or neoadjuvant immunotherapy might be considered
• Unresectable tumors where surgery and/or radiation would not be curative or would lead to unacceptable morbidity

To test how well such a staging system would work with actual cases, the researchers conducted a retrospective study at three academic centers of cSCC tumors diagnosed between 1999-2024. They included AJCC8 stage III and IV tumors, including ones greater than 4 cm in the trunk or extremities and those with in-transit metastasis or incomplete nodal staging features. They compared the incidence of disease progression and mortality when using both the AJCC8 and the proposed PCS systems. 

Of the 812 patients initially identified, they ended up with 510 who could be staged in both systems based on charts, photos, and imaging at the time of the disease presentation. Most of the patients were male (77%) with head and neck tumors (80%). The sample included 28% of patients who were immunosuppressed and 40% with metastatic disease. 

Under the AJCC8 system, 47% of the cases were stage III, 21% were stage IV, and 32% could not be staged. Under the PCS system, 31% of the tumors were classified as high stage, 48% were classified as resectable, and 21% were classified as unresectable. Gibson showed how proportions of the AJCC8 staged cases moved into different categories under the PCS system. 

For example, among the 108 stage IV cases under AJCC8, nearly a third (31%) moved into the unresectable PCS category while 69% moved into the resectable category. Similarly, the 165 AJCC8 unstageable cases split such that 16% moved into the high stage PCS category, 52% moved into the resectable category, and 33% moved into the unresectable category. 

When the researchers looked at disease progression rates under AJCC8 staging, 39% of the stage III cases progressed and remained distinct from incidence in stage IV and unstaged cases. However, progression rates for stage IV (62%) and unstaged cases (59%) overlapped substantially, preventing meaningful prognostic discrimination between the two.

Under the PCS system, however, the incidence of progression was much more distinct among the three groups: 74% of unresectable cases progressed compared with 54% of resectable ones and 27% of high stage cases. Even within a single stage — the 39% of stage III cases under AJCC8 that progressed — disease progression remained distinct, with progression in 67% of cases reclassified as unresectable, 55% of the cases reclassified as resectable, and 23% of cases reclassified as high stage. 

Prognostic discrimination was similarly more distinct with the PCS system when looking at disease-specific death rates. Under the AJCC8 system, death occurred in 37% of stage IV cases, 31% of unstaged cases, and 10% of stage III cases, again showing substantial overlap between the stage IV and unstaged cases. 

Under the PCS system, however, mortality was 50% among unresectable cases, 21% of resectable cases, and 6% of high stage cases, with a far greater absolute gap between unresectable and resectable deaths. Gibson again demonstrated the greater prognostic distinctions of PCS staging with the 37% of patients with stage III disease who died. Under PCS, mortality was 66% among unresectable cases compared with 23% of resectable ones. 

The advantage of PCS classification is that it’s inclusive, distinctive, and clinically relevant, Gibson said. It applies to all advanced cSCC cases, it improves diagnostic discrimination, and it reflects modern guidelines, clinical trials, and current clinical practice. 

“TNM staging does not have to be a one-size-fits-all for cancer,” he said. “A modern staging system will improve risk stratification, guide management, sharpen clinical trial design, and improve patient care.” 

Gibson acknowledged that the PCS system needs further refinement with modern cohorts and would need to be integrated into emerging treatments and clinical tools. 

Jordan Lim, MB, BCh, BAO, assistant professor of dermatology and board-certified Mohs surgeon at Emory University in Atlanta, told Medscape Medical News that she saw the proposed PCS system as a potential adjunct to what’s currently being used in staging. 

“It was really interesting, and I think Brigham is the place that questions our staging for the better,” Lim said, noting previous work with the Brigham and Women’s Hospital tumor classification systems for cSCC. 

“It needs to be a little more granular, and it will be interesting once it’s actually applied more prospectively or to broader patient populations,” she said, “but it is helping to define patients that haven’t been defined yet, that have been just lumped together in one staging area. I think it’s exciting and we’ll see more about it.” 

No external funding was noted for the study. Gibson and Lim both had no disclosures. 

Tara Haelle is a science/health journalist based in Dallas.