Treatment of OCSCC involves resection of the primary tumor, followed by neck dissection or postoperative radiotherapy when needed, but choice of treatment requires an accurate assessment of resection margins. Previous studies have failed to consistently show a correlation between margin status and clinical outcomes. Tumor size, depth of invasion, and other factors may explain inconsistent findings, but another possibility is the variability in how margin status is defined.
RCPath and CAP are among the most commonly used definitions. RCPath defines a positive margin as invasive tumor within 1 mm of the surgical margin, while CAP defines a positive margin as the presence of primary tumor or high-grade dysplasia at the margin itself. CAP recommends determination of a “final margin status” that also considers separately submitted extra tumor bed margins. Nevertheless, multiple studies have shown that reliance on the main tumor specimen outperformed the combined approach in predicting recurrence and survival.
In a study published online March 7 in Oral Oncology, researchers examined records from 300 patients (33.7% of whom were female) at South Infirmary Victoria University Hospital in Ireland between 2007 and 2020. The researchers found that 28.7% had margins determined by the RCPath definition and 16.7% according to the CAP definition. Forty-nine percent underwent extra tumor bed resections.
The mean follow-up period was 49 months, 64 months for surviving patients. Multivariate analyses accounting for other established prognosticators found that local recurrence was associated with CAP margins (odds ratio [OR], 1.86; 955 confidence interval [CI], 1.02-3.48) and T3/T4 classification (OR, 2.80; 95% CI, 1.53-5.13). CAP margins predicted disease-specific survival (OR, 2.28; 95% CI, 1.53-5.13) and narrowly missed significance in predicting overall survival (OR, 1.65; 95% CI, 0.99-2.75). RCPath margins were not predictive.
The researchers found a significant association between RCPath definition and metastatic nodal disease and extranodal extension, but there was no such relationship between these negative predictors and CAP and final margin status. “This finding may explain the superior independent prognostic ability of CAP margin status over RCPath in our cohort and is consistent with that of previous studies, which concluded that other histological risk factors are more important than margin status in predicting outcome,” the authors wrote.
Studies suggest that margins fewer than 1 mm remain a high-risk group, with worse survival outcomes than those of patients with 1- to 5-mm margins, even if the risk is lower than tumor at margins. “The optimum cut-off between low-risk and high-risk margins in OCSCC remains unresolved,” the authors wrote.
The study was retrospective and relied on data from a single center, and the patients included in the study may not be directly comparable to other OCSCC patients. The study was funded by the Head and Neck Oncology Fund, South Infirmary Victoria University Hospital.