Rapid visualization of nonmelanoma skin cancer.

BACKGROUND Mohs micrographic surgery examines all margins of the resected sample and has a 99% cure rate. However, many nonmelanoma skin cancers (NMSCs) are not readily amenable to Mohs micrographic surgery. This defines an unmet clinical need to assess the completeness of non-Mohs micrographic surgery resections during surgery to prevent re-excision/recurrence. OBJECTIVE We sought to examine the utility of quenched activity-based probe imaging to discriminate cancerous versus normal-appearing skin tissue. METHODS The quenched activity-based probe GB119 was applied to NMSC excised from 68 patients. We validated activation of the probe for hematoxylin-eosin-confirmed cancerous tissue versus normal-appearing skin tissue. RESULTS Topical application of the probe differentiated basal cell carcinoma and squamous cell carcinoma from normal-appearing skin with overall estimated sensitivity and specificity of 0.989 (95% confidence interval 0.940-1.00) and 0.894 (95% confidence interval 0.769-0.965), respectively. Probe activation accurately defined peripheral margins of NMSC as compared with conventional hematoxylin-eosin-based pathology. LIMITATIONS This study only examined NMSC debulking excision specimens. The sensitivity and specificity for this approach using final NMSC excision margins will be clinically important. CONCLUSIONS These findings merit further studies to determine whether quenched activity-based probe technology may enable cost-effective increased cure rates for patients with NMSC by reducing re-excision and recurrence rates with a rapid and easily interpretable technological advance.