What is photodynamic therapy? What is its mechanism of action? List ENT disease where this modality of treatment is applicable?

Photodynamic therapy (PDT) is a subset of photo-chemotherapy where in addition to an administration of drug and application of light, oxygen is required to complete the process.

Th administrated of drug is called “photosensitizer”. These types of drugs accumulated within a cell and reacts with light and oxygen to form “singlet oxygen”. The “singlet oxygen” damages the cell membranes and produce a cell death.

Advantages

• Photosensitizers are retained in tumours cells for a longer period than in normal tissue which improves therapeutic effect and reduces toxicity to normal tissue.
• The use of PDT is not affected by prior radiotherapy chemotherapy or surgery.

Disadvantages

• Limited depth of tissue penetration
• Extensive Stein phototoxicity

Drug-light interval or Drug uptake period: 3-96 hours

INDICATED USE OF PHOTODYNAMIC THERAPY IN ENT DISEASE

The following are ENT diseases where the modalities is applicable

Malignant tumours

• SCC of larynx (early)
• SCC of oral cavity
• SCC of Nasopharynx
• Metastatic SCC of neck
• Oesophageal carcinoma

Non-malignant diseases

• Inverted papilloma

 

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