Alternative Local Treatment in Oral Cavity Cancer: Photodynamic Therapy

The standard treatment for early stage oral cancer is surgery with or without adjuvant radiotherapy. For some patients such treatments are not applicable, for example when adequate re-irradiation doses cannot be given due to previous therapy or when further surgery would be expected to lead to unacceptable functional morbidity. Photodynamic therapy (PDT) might be an alternative for these patients. PDT is based on the interaction of three essential components: a photosensitizer i.e. a light sensitive drug, light and oxygen. The photosensitive drug is initially not toxic, but if activated by light it can interact with oxygen resulting in the formation of highly reactive oxygen species. Reactive oxygen species can readily oxidize biomolecules leading to cell death. The penetration depth of red laser light in tissue is limited to about ~8–10 mm depending on the optical properties in the tissue. Light can be delivered by surface or, intraluminal illumination for superficial tumors and by interstitial illumination for sub mucosal bulky tumor masses. For interstitial illumination light emitting catheters are inserted directly into the tumor tissue, ensuring the possibility to treat thicker tumors. Good, curative results have been achieved in the treatment of early stage oral cancer. The results are comparable to surgery. Also, in the palliative setting, encouraging results have been achieved, with preservation of quality of life. With surface illumination the treatment has a low morbidity on the long term with good functional and cosmetic results.