Photodynamic Therapy, PDT

When photosensitizer -accumulated tumor cells are irradiated with a light of certain wavelength, reactive oxygen species(ROS) are generated via photochemical reaction. Generated ROS selectively damage the tumor cells by direct induction of apoptosis and necrosis, and indirect induction of immunological effects, hypoxia and starvation of tumor by damaging the vasculatures of the tumor and its surrounding vessels. These chains of procedures are known as photodynamic therapy(PDT).

Photodynamic diagnosis, PDD

Photosensitizer has a photochemical feature of UV-fluorescence (i.e. 405nm light activates certain 2nd generation photosensitizer to produce red-light). With this photochemical feature of photosensitizer, the tumor loci can be specified during operation. This procedure is known as photodynamic diagnosis(PDD). PDD is expected to increase the surgical success rate by diagnosing traditionally undiagnosable tumor loci during operation, via fluorescence endoscopy/laparoscopy.

Classic PDT(Conventional PDT)	Interstitial PDT(I-PDT)
Surface-tumor light delivery	Intra-tumor* light delivery * Fiber optic probe is inserted into the targeted tumor via puncturing with needle
Effective in treating tumors that are widely distributed on the surface (e.g. Peritoneal cancer, BCC, etc.)	Effective in treating locally advanced solid cancers and deeply embedded tumors (e.g. Pancreatic cancer, Brain tumor, etc.)
	Minimizes side effects by applying the energy(light) only to the tumor cells,but not to the surrounding normal tissue ⇒ Maximizes therapeutic effect
To maximize the efficacy of energy(light) delivery, selective usage in the type of fiber optic probe according to the morphological characteristics of tumors is necessary.

1. Injection
Due to photosensitizer’s light sensitivity, the patient will receive an intravenous infusion of photosensitizer in the darkroom.

2. Accumulation
After photosensitizer selectively accumulates in the tumor tissue, the patient will be moved to the operating room for PDT.

3. Irradiation
The patient will receive either laparoscopic or endoscopic PDT via a set of laser devices.

4. Reduction
ROS(Reactive Oxygen Species), which are generated via photochemical reaction, induces tumor size reduction.

5. Recovery
After PDT is complete, the patient must stay in a darkroom to washout the remnant photosensitizer and prevent unnecessary phototoxic reaction.

Patient Guide

Before Treatment
ㆍPhotosensitizer should not be used in patients with blood disorders such as porphyria.
ㆍLocal swelling and inflammation in and around the treated area may cause physical discomfort in that area after the treatment.
ㆍAsk your doctor if photosensitizer is right for you.

After Treatment
ㆍPDT will make your skin and eyes sensitive to bright light(photosensitivity), meaning that you can experience effects similar to sunburn if you are exposed to light.
    → You must protect your skin and eyes from sunlight and stay in a darkroom to washout the remnant photosensitizer.
ㆍIf you go out during daylight hours, talk to your doctor and do not leave any part of your body unprotected.
    → Do this by wearing protective clothing, socks, shoes, a wide-brimmed hat, scarf, and gloves.