Ann. Coll. Surg. H.K. (2002) 6, 42–47 Original article Photodynamic therapy in malignant brain tumour: Is intratumoral injection of photosensitizer superior to conventional intravenous administration? Yung Chan ( ), 1 * Sin-Ming Ip ( ), 1 Wai-Sang Poon ( ) 1 and Nicholas Wickham 2 Division of Neurosurgery, Departments of 1 Surgery and 2 Oncology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR. Objective: Selective uptake and retention of haematoporphyrin derivative (HpD) in tumour tissue, especially at brain adjacent to the tumour (BAT) region, is an important factor in determining the efficacy of photody- namic therapy (PDT). The uptake and distribution of HpD was studied in 10 patients with malignant glioma. Method: Five cases were injected with HpD intravenously at a dose of 5 mg/kg bodyweight. Another five cases were injected with 10 mg (2 mL) HpD by ultrasound guidance into the tumour centre. After 24 h, the patients underwent craniotomy for tumour debulking. Biopsies of the tumour tissue and BAT region were sent for analysis. Results: In the intravenous administration group, the mean HpD level in the tumour centre was 2.0 ± 0.7 mg/g, which was lower than the level of HpD in the BAT region (3.6 ± 2.3 mg/g; P > 0.05). However, in the intra- tumoral injection group, the level of HpD was much higher in the tumour centre than in the BAT (4.7 ± 3.2 mg/g vs 1.4 ± 0.4 mg/g; P < 0.05). Fluorescence microscopy observations showed that HpD was distributed unevenly at the periphery of the blood vessels and stroma in the intravenous group. Bright and patchy distribution of HpD was also seen in the tumour centre after direct intratumoral injection. Intracellular uptake of HpD could be observed in the BAT region of both groups. Further study with a confocal laser scanning microscope (CLSM) provided evidence that HpD was localized intracellularly. Conclusion: The study showed that conventional intravenous administration of HpD can achieve a higher level in the BAT region, but the distribution of HpD varied and was unpredictable. Intratumoral injection can achieve a much higher HpD in the tumour centre; however, the distribution in the BAT region is unsatisfac- tory because of the irregular shape of the tumour mass. Taking into account this variable result, the HpD level may need to be tailored to meet each individual patient’s requirement. Key words: brain tumour, haematoporphyrin derivative, photodynamic therapy. ment of residual tumour cells is critical in the control of tumour recurrence. Photodynamic therapy (PDT) is being investigated as an adjuvant treatment for malignant tumour. Since the first trial of PDT in human glioma was reported by Perria and colleagues 1 more than 270 cases of intracranial neoplasms have been treated with PDT using a variety of treatment protocols. 2 However, the outcome has been unsatisfactory. Although tumour necrosis could be observed by microscopy or imaging examination, most treatmens failed due to local recurrence after PDT. *Author to whom correspondence should be addressed. Email: chanyung01@yahoo.com.hk Received 15 October 2001; accepted 1 February 2002. Introduction Even with combined therapy, the prognosis for malig- nant glioma is unsatisfactory. The poor prognosis is due to local recurrence of glioma. Usually the tumour cells invade normal brain tissue diffusely, and are beyond the reach of resection. Hence, the manage-