ABSTRACT Melanoma is the fifth most common cancer in the US with almost 100,000 cases estimated for 2023. Late-stage disease has a five-year survival of just 30%, resulting in almost 8,000 deaths in the US alone. When detected early, melanoma has a survival rate of 99%; however, a widely adopted screening tool for melanoma currently does not exist. The current standard of care in skin cancer detection relies on a clinical visual assessment of moles, followed by an invasive biopsy of suspicious lesions. The low accuracy of this approach (84% sensitivity and 3-16% specificity) leads to missed melanomas and high rates of “unnecessary biopsies”, biopsies of benign moles. An average of 25 biopsies are required for each melanoma found, resulting in 3 million biopsies of benign moles each year. For this reason, the US Preventative Services Task Force does not recommend routine visual screening for skin cancer in adults, citing the potential harm of the high rate of unnecessary biopsies. Non-invasive genetic or spectroscopic tests that are currently available have either sensitivities that are too low (below 98%) or specificities that are too low (below visual assessment). We hypothesize that limited applicability of these approaches stems from the limited availability of melanoma biomarkers. Studies have shown that a combination genetic markers and histological analysis offer an excellent combination for specific and sensitive diagnosis; however, no minimally-invasive technology exists to provide samples for this purpose. We propose a “laser microbiopsy” as a technique to harvest microliter-sized tissues, using a ring-shaped infrared laser such that the center of the annulus can be removed with minimal damage by a pulse of light. Because laser tissue removal is essentially instantaneous (within microseconds) and the biopsy size is on the scale of hundreds of micrometers, the procedure is potentially much less harmful than traditional punch biopsies. Importantly, our preliminary work shows that the laser microbiopsy penetrates through the epidermis and to the melanocytes, where melanoma originates. To further develop this approach, we will refine and characterize the performance of the laser microbiopsy hardware (Aim 1) and validate viability of extracted micro-biopsies for molecular analysis (Aim 2). We envision our approach providing pain-free tissue for offline pathology and molecular analysis of melanoma as well as a possible surgical guidance tool for real-time assessment of tumor margins. In addition, harvested tissues could be used for primary tissue cultures or flow cytometry. Once this proof-of-principle (R61) project is complete, we anticipate transitioning the laser microbiopsy from a developmental phase to test feasibility for melanoma diagnosis in an R33 application.

Narrative Current methods for tissue biopsy methods are prohibitively painful and thus not recommended for comprehensive melanoma screening in adult individuals, resulting in significant missed cancers. Noninvasive methods that sample only the top layer of the skin for molecular (non-histological) analyses are not widely used for melanoma diagnosis, likely due to collection of biomarkers from superficial skin rather than from melanocytes that are deeper under the skin. In this proposal, we propose development of a new laser microbiopsy that will allow tissue extraction beyond the epidermis, where melanocytes are located, with less pain compared to traditional biopsies. This minimally-invasive laser microbiopsy can be used for histological and molecular diagnostics, which will hopefully allow for comprehensive melanoma screening to reduce the disease burden.