Photodynamic therapy of malignant brain tumors: supplementary postoperative light delivery by implanted optical fibers: field fractionation

Sixty-three patients with malignant brain tumors were treated with intraoperative photodynamic therapy (PDT) using an argon dye pump laser and preoperatively administered hematoporphyrin derivative or dihematoporphyrin ether. In 13 cases, in addition to cavitary photo-illumination, cylindrical diffusion fibers were used to increase the amount of light energy administered to the tumor tissue intraoperatively. This interstitial photo-illumination was tolerated at light energy densities of less than 450 J/cm. In six recent cases, all of whom had large malignant gliomas and could not be illuminated adequately at a single session, cylindrical diffusion fibers were left in situ after intraoperative cavitary photo-illumination of the tumor residuum. The fibers were protected from fracturing by placing all but the exposed diffusing end in a red rubber catheter of the appropriate diameter. The fibers were externalized through a separate stab wound as would be the case for a ventricular drain. Photo-illumination was continued one or two days post-operatively. The optimal fiber couple to the argon dye pump laser was achieved by assessing the fiber side scatter with a photometer. These six patients received 585-2730 Joules during the post-operative photo-illumination. The patients tolerated the fractionated photo-illumination well. A transient scalp inflammation occurred as the consequence light transmission to skin from the implanted fibers in one case. The median survival for the whole series was 8.5 months (40 weeks) with a 1- and 2-year actuarial survival rate of 33, respectively.