The "gold standard" of assessing pathological changes in tissue is currently histopathology. However, the processing of biopsy material and the interpretation of the results inevitably leads to diagnostic delay and the added possibility of taking an unrepresentative sample. Recently, there has been increasing interest in the use of optical biopsy systems to be able to provide tissue diagnosis in real-time, non-invasively and in situ. These systems rely on the fact that the optical properties derived from any tissue will contain information about the histological and biochemical make up of that tissue. The technique has not only been shown to have a role in the detection of dysplasia (pre-cancer) and malignancy (cancer) but also in performing guided biopsies, monitoring of haemoglobin tissue perfusion in free-flaps and therapeutic drug levels during chemo- and photodynamic therapy. The obvious advantages of being able to accurately diagnose pathology without the need to remove a tissue sample diminish patient trauma as well as having financial implications.
Photodynamic therapy (PDT) is a minimally invasive modality, successfully targeting premalignant (pre-cancer) and malignant (cancer) disorders in the head and neck, gastrointestinal tract, lungs and skin. Unlike other treatment options, it is associated with greatly reduced morbidity and disfigurement. The technique is simple and can usually be carried out in outpatient clinics, with a high patient-tolerance rate. PDT is based on initial sensitization of the target tissue with an agent with photosensitizing properties. The agent selectively accumulates in target tissue (pre-cancer or cancer). The subsequent light delivery to the target tissue results in cellular destruction. The photochemical reaction following PDT is nonthermal (cold). The photosensitising agents exhibit an inherently low systematic toxicity and, significantly, have a remarkably little effect on connective tissues, thus resulting in healing with minimal scarring. When used in hollow organs such as the airways, the luminal integrity is retained without fibrous tissue formation. Major blood vessels maintain their mechanical integrity as collagen and elastin are largely spared. This therapy can be applied in conjunction with any of the conventional treatment modalities (i.e. surgery, radiotherapy or chemotherapy). The treatment can be repeated as often as necessary since it has no cumulative toxicity.
Over the past few decades, the use of lasers among oral and maxillofacial/head and neck surgeons has grown dramatically. Their evolution within the specialty not only has broadened current surgical options for treatment, but also contributed to a variety of new procedures that are now a commonplace in head and neck surgery. Their effect on tissue is determined by their wavelength and the tissue specific absorption. Lasers can be used for evaporation, excision and coagulation of tissue. The commonly used lasers include carbon dioxide (CO2), neodymium:yttrium-aluminium-garnet (Nd:YAG) and Argon lasers.
Photochemical internalization (PCI) is a novel technology facilitates the delivery of macromolecules into cytoplasm. It can best be described as sub-lethal photodynamic therapy (PDT) facilitating the effect of chemotherapy. The, first in human trial, to evaluate the safety and tolerance of the photosensitizer (amphinex) that is used to initiate the photochemical internalization (PCI) process with bleomycin as the chemotherapeutic agent is now completed and the initial results show great promise.