Spectrally Guided Mohs Surgery
Condition: Skin Cancer
MeSH terms: Skin Neoplasms
Study type: Observational

Summary: 
      Freshly excised or freshly frozen tissue for Raman analysis will be obtained from a
      dermatology practice affiliated with UMCB. In the course of the routine removal of benign or
      malignant tumors in the office, skin cancer surgeons routinely check frozen sections to
      ensure adequate margins are obtained. Consent will be obtained from patients to provide
      freshly excised or freshly frozen leftover tissue obtained during Mohs surgery to be
      discarded after histological diagnosis. Freshly excised tissue will be measured at the time
      of excision before processing, while the freshly frozen tissue samples will be stored in a
      freezer at the Mohs clinic and transferred to the UT- Austin campus for spectroscopic
      analysis.
    

Detailed description: 
      The current standard-of-care in the identification of skin cancer is visual inspection
      followed by biopsy and histopathology of suspicious skin sites. Since a physician is required
      to perform this biopsy, there is often a delay in diagnosis, resulting in deeper, more
      aggressive tumors and increased mortality from malignant melanoma (MM). Therefore, a
      non-invasive method to inspect these lesions would be of great clinical importance.

      An initial prototype of a noninvasive diagnostic device was developed based on optical
      spectroscopy and completed a clinical study in 76 patients that demonstrated high diagnostic
      accuracy for the detection of skin cancer (IRB # CR-10-004). This initial prototype consisted
      of two separate devices and probes: one to collect Raman spectra (RS) and the other to
      collect diffuse reflectance and laser induced fluorescence spectra (DRS+LIFS). type, but a
      combination of modalities gave the best diagnostic performance for all types of skin cancer.

      The addition of Raman spectroscopy improved diagnostic performance for both melanoma and
      non-melanoma skin cancer. However, the operation of the integrated systems was still
      conducted via two optical fiber probes (the first one for fluorescence and reflectance
      spectroscopy, the second one for Raman spectroscopy). The need to take measurements of the
      same lesion using two probes increased acquisition time, and the possible sampling site
      error. Recently, a device was developed that combined fiber optic probe that is capable for
      spectral acquisition of Raman, white light reflectance and laser induced fluorescence
      spectroscopy. Using this probe, acquisition time and sampling site error should be reduced.
      There is no significant difference in terms of performance between the previous two probes
      and the new probe.

      Models have been developed to analyze reflectance and fluorescence spectroscopy data. In
      order to interpret Raman spectroscopy data in physiologically relevant parameters, a
      biophysical model needs to be developed. Similar models have been developed by other research
      groups for other types of tissue.

      This study proposes to use the new technique of biophysical modeling to analyze our Raman
      spectra. At the core of the technique is the measurement of a set of "basis spectra" which
      are fit to the data using ordinary least-squares. Recently, biophysical models have been
      developed for atherosclerosis and breast cancer with very impressive diagnostic results,
      achieving 94% sensitivity and 96% specificity for breast cancer and 94% accuracy for
      atherosclerosis disease classification.

      Raman microspectrometry will be used to measure basis spectra from various skin constituents.
      In this technique, Raman spectra are measured from freshly frozen tissue samples that are
      sliced into thin sections as is done in histology. A microscope system is used to focus the
      excitation laser beam to a small spot of approximately 2 mm in diameter on the sample, and a
      Raman spectrometer measures the emitted Raman spectrum. In this way, Raman spectra of
      individual microscopic tissue components can be isolated. These individual component spectra
      will be determined for keratin, cell nuclei, collagen, cytoplasm, melanin, water, sebaceous
      glands, etc.
    

Intervention name(s): Multimodal Spectroscopy
Intervention type(s): Device
Intervention description(s): optical measurement of excised tissue
Observational model: Other
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        All patients undergoing treatment for SCC or BCC in local Mohs surgery clinic