PDT is a new Tumor specific therapy which destroys cancer cells only with almost no effects on normal cells as injecting a photosensitizer friendly to cancer cells into the vein and then exposing to a specific wavelength of laser light to excite it. It is less destructive than the conventional chemotherapy or radiotherapy and does not cause a treatment trouble due to resistance because its operation mechanism induces necrosis of cells.

PDT utilizes a mechanism that photosensitizer injected into the vein is accumulated selectively in tumor tissue cells and tumor blood vessel tissue and the photosensitizer is exited by exposing to single wavelength of laser light which can be absorbed only by the photosensitizer, and the energy is transmitted to oxygen molecules in tumor tissues, which generate reactive oxygen species (singlet oxygen, oxygen radical, superoxide and peroxide radical) that destroy/kill cancer cells directly by acting on components of a cell or inducing adhesion of blood vessel by inhibiting formation of new blood vessel, or destroy/kill selectively tumor tissue only by inducing apoptosis with secondary reaction according to oxidative stress or by mixed methods accompanied with immunological reaction.

- Advantages of PDT

1. Possible to use for the purpose of fundamental treatment of early stage cancer instead of operation, Possible to use as a neoadjuvant photo-dynamic therapy for reducing range of tumors to the extent possible of operation. Applicable as a palliative photodynamic therapy for dyspnea or hemoptysis, Aapplicable to cases that operation, anti-cancer therapy or radiotheraphy has been failed.
2. A tumor specific therapy to cure only cancer cells without affecting normal cells, No pains or unpleasant feeling to a patient, so easily applicable to patients who have a difficulty in operation or other anti-cancer therapies.
3. Enhancement of quality of life because functions of organs are preserved after treatment. (uterine cancer - preservation of regenerative function, colorectal cancer preservation of evacuation function of the anus, laryngopharyngeal cancer preservation of voice of the vocal cords)
4. Low toxicity, High selectiveness of cancer cell, High cure rate (70~95%) with low recurrence (<5%)
5. High efficiency in spite of short reaction time (1ms~10μs), Applicable as photodynamic diagnosis

 Radachlorin among photosensitizers applied to photodynamic therapy is more excellent in efficacy and stability than Canadian QLT's Photofrin. Photofrin has a demerit that the depth of its penetration into cancer cell is only 5mm because the peak absorption wavelength of the light is 630nm while Radachlorin has the peak absorption wavelength 662nm and the depth of its penetration is over 1Cm, so it is effective for treatment of a solid cancer. Also Radachlorin can treat within 3~5hours by shining the light and it does not cause a problem of photosensitivity disease because it can be excreted within 3~5 days while it takes 1~2 months for excretion of Photofrin.