Staging for Cutaneous Squamous Cell Carcinoma as a Predictor of Sentinel Lymph Node Biopsy Results

Abstract

The appropriate clinical setting for the application of sentinel lymph node biopsy (SLNB) in the management of cutaneous squamous cell carcinoma (cSCC) is not well characterized. Numerous case reports and case series examine SLNB findings in patients who were considered to have high-risk cSCC, but no randomized clinical trials have been performed. To analyze which stages in the American Joint Committee on Cancer (AJCC) criteria and a recently proposed alternative staging system are most closely associated with positive SLNB findings in nonanogenital cSCC. Medical literature review and case data extraction from private and institutional practices to identify patients with nonanogenital cSCC who underwent SLNB. Patients were eligible if sufficient tumor characteristics were available to classify tumors according to AJCC staging criteria and a proposed alternative staging system. One hundred thirty patients had sufficient data for AJCC staging, whereas 117 had sufficient data for the alternative system. Nonanogenital cSCC and SLNB. Positive SLNB findings by cSCC stage, quantified as the number and percentage of positive nodes. A positive SLN was identified in 12.3% of all patients. All cSCCs with positive SLNs were greater than 2 cm in diameter. The AJCC criteria identifed positive SLNB findings in 0 of 9 T1 lesions (0%), 13 of 116 T2 lesions (11.2%), and 3 of 5 T4 lesions (60.0%). No T3 lesions were identified. The alternative staging system identified positive SNLB findings in 0 of 9 T1 lesions (0%), 6 of 85 T2a lesions (7.1%), 5 of 17 T2b lesions (29.4%), and 3 of 6 T3 lesions (50.0%). Rates of positive SLNB findings in patients with T2b lesions were statistically higher than those with T2a lesions (P = .02, Fisher exact test) in the alternative staging system. Our findings suggest that most cSCCs associated with positive SLNB findings occur in T2 lesions (in both staging systems) that are greater than 2 cm in diameter. The alternative staging system appears to more precisely delineate high-risk lesions in the T2b category that may warrant consideration of SLNB. Future prospective studies are necessary to validate the relationship between tumor stage and positive SLNB findings and to identify the optimal staging system.