Photodynamic therapy

: Treatment that destroys cancer cells with lasers and drugs that become active when exposed to light.

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(PDT, photoradiation therapy, phototherapy, photochemotherapy)

a treatment for some types of superficial cancers. A photosensitizing agent is injected into the bloodstream and remains in cancer cells for a longer time than in normal cells. Exposure to laser radiation produces an active form of oxygen that destroys the treated cancer cells. The laser radiation can be directed through a fibreoptic bronchoscope into the airways, through a gastroscope into the oesophagus, or through a cystoscope into the bladder. PDT causes minimal damage to healthy tissue, but as it cannot pass through more than about 3 cm of tissue, it is restricted to treating tumours on or just under the skin or on the lining of internal organs. Photodynamic therapy makes the skin and eyes sensitive to light for six weeks or more after treatment.

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(PDT) intravenous administration of a photosensitizing agent such as hematoporphyrin derivative, which concentrates selectively in metabolically active tumor tissue, followed by exposure of the tumor tissue to red laser light of a specific wavelength, to bring about production of cytotoxic free radicals that selectively destroy the photosensitized tissue. Called also photochemotherapy, photoradiation, phototherapy, and light therapy.