BI09 The OCTOPUS study (Optical Coherence Tomography in OutPatient dermatology UnitS): can noninvasive imaging improve diagnosis of keratinocyte (pre)cancers in immunosuppressed and immunocompetent patients?

Abstract Around 250 000 keratinocyte cancers (KCs, comprising basal and squamous cell carcinomas) are diagnosed annually in the UK, and the incidence is rising by 5–6% per year. Because early KC diagnosis leads to improved outcomes, the number of routine diagnostic biopsies performed for clinically suspected skin cancers significantly exceeds this, as many lesions prove histologically benign. Unnecessary skin biopsies are associated with increased costs to both patients and healthcare resources, and for immuno­suppressed patients, who are at increased risk of skin cancer, the burden of repeated biopsies, including scarring and patient anxiety, may be considerable. Noninvasive imaging technologies such as optical coherence tomography (OCT) and the recently developed line-field confocal OCT (LC-OCT) have been demonstrated to accurately and rapidly diagnose premalignant and malignant skin lesions, including KC. OCT allows in vivo imaging of skin lesions. It provides vertical slice imaging of lesions up to 2 mm in depth with a relatively wide field of view (36 mm2), allowing assessment of diagnosis, depth and margins, but its resolution is not sufficient to visualize detail at the individual cellular level. LC-OCT is effectively a combination of OCT with reflectance confocal microscopy, with higher cellular-level resolution than conventional OCT, but with a smaller field of view and a shallower depth of penetration. OCT is widely used in some European countries, in which it has become standard of care in KC diagnosis. However, experience in the UK is limited to a few centres and has not been evaluated in a National Health Service (NHS) setting. OCTOPUS is a single-centre, nonrandomized prospective study of OCT and LC-OCT in the diagnosis of keratinocyte (pre)cancers, and is a feasibility study for a future randomized controlled trial (RCT). Inclusion criteria for this real-world study are adult patients referred by a dermatologist for biopsy of suspected keratinocyte (pre)cancers. The primary objective is to study the diagnostic accuracy of OCT and LC-OCT (with and without integrated artificial intelligence-based assistance) compared with histopathology. Secondary outcomes include health economic evaluation, accuracy of basal cell carcinoma subtyping and patient-reported outcomes. Preliminary data provide a signal of diagnostic utility and significant enthusiasm for the technologies among patient groups. Potential benefits of OCT-based imaging include a more rapid diagnostic pathway, reduction in diagnostic biopsies, more rapid and appropriate treatment including nonsurgical treatment for premalignant lesions, improved surgical planning, and cost savings for the NHS through reduced biopsies and fewer patient visits. These outcomes will be evaluated in a future RCT.