2008 Volume 29 Issue 2 Pages 135-146
The treatment results for malignant brain tumors are not encouraging, and the postoperative survival time in patients with glioblastoma is only 1.5 year on an average. Although multidisciplinary treatment is conducted for malignant brain tumors similar to that for cancers in other organ, it has become apparent from recent developments in surgical methods that if a brain tumor could be completely removed macroscopically, postoperative survival time would also be significantly improved. Nonetheless, it is extremely difficult to differentiate a malignant brain tumor from normal brain tissues by naked eye or under surgical microscope. In particular, when a malignant brain tumor infiltrates into the normal brain tissues or is present near the eloquent brain area, serious complications may occur after extensive surgical removal.
Photodynamic medicine includes the use of photodynamic diagnosis (PDD) and photodynamic therapy (PDT). PDD is a diagnostic method for differentiating tumor tissues from normal tissues by detection of fluorescence in malignant brain tumor tissues during tumor removal. 5-Aminolevulinic acid (ALA) is used as a photosensitizer for PDD. PDT is a local therapeutic method for malignant brain tumors using a photosensitizer and light. Hematoporphyrin derivative (HpD) is used as a photosensitizer for PDT. In the present study, 250 brain tumor patients were treated using PDD and 63 patients underwent PDT. Based on our clinical experience, the advantages and disadvantages of PDD and PDT can be summarized as follows. Advantages: (1) PDD enabled to differentiate malignant brain tumor tissues from normal brain tissues by naked eye before tumor removal during surgery. (2) Macroscopic total removal of the malignant brain tumor was possible by using PDD, and PDD might contribute to prolong patient survival. (3) PDT might be effective for treating malignant brain tumor that has invaded the eloquent brain area and small deep-seated tumor in the brain. (4) Photodynamic medicine (PDT and PDT) has fewer side effects and offers a good quality of life. Disadvantages: (1) In PDD, it is very difficult to differentiate infiltrative tumor tissues or guerilla cells from normal tissues. Additionally, false-negative and false-positive findings are obtained, especially in brain edema tissues or recurrent tumor tissues. (2) In PDT, the depth of light penetration into the tumor tissue is limited. (3) The concentration of the photosensitizer and the oxygen in malignant brain tumor tissues is heterogeneous.
Conclusion: Photodynamic medicine involving PDD and PDT is very effective for the treatment of malignant brain tumors.
