Photodynamic therapy of malignant brain tumours

Abstract

Experience with intraoperative PDT in 50 patients with malignant supratentorial tumours is reported; in 33 cases the tumour was recurrent. In 45 patients the tumour was a cerebral glioma and in five cases a solitary cerebral metastasis. There were 29 males and 17 females with an age range of 17–73 (mean 48) years. All patients received either haematoporphyrin derivative (HPD) or dihaematoporphyrin ether (DHE) 18–24 h preoperatively. A photoilluminating device, of the authors' design, was coupled to an argon dye pump laser in order to deliver light at 630 nm to a tumour cavity created by radical tumour resection and/or tumour cyst drainage. The total light energy delivered ranged from 440 to 3888 J and the light energy density ranged from 8 to 175 J/cm². In eight patients a line fibre(s) was used to administer interstitial light as a supplement to the cavitary photoillumination. The additional light dose ranged from 60 to 945 J/cm.

There were two postoperative deaths as the consequence of haematoma accumulation in the tumour resection cavity. In three patients neurological function was worse postoperatively and did not recover. Postoperative cerebral oedema was pronounced in some cases and required second craniotomy in two patients (the histology from both showed haemorrhagic necrosis of residual tumour). Four patients developed wound infections; two of these required surgical treatment. Four patients, two of whom were hemiparetic, developed deep vein thrombosis and required anticoagulant therapy. There were no adverse systemic reactions to the administration of either photosensitizer and only three skin photosensitivity reactions.

Follow up ranged from 1 to 30 months. In the group of 45 patients with gliomas the death rate per observation year was 0.92 for the interval between PDT and death. For the interval between first diagnosis and death the rate was 0.41 deaths per observation year. The median survival was 8.6 months with a 1 and 2 year actuarial survival rate of 32% and 18%, repectively.

In 12 patients a complete or near complete CT scan response was identified post PDT. These patients tended to have a tumour geometry (e.g. cystic) that allowed complete or near complete light distribution to the tumour. The median survival for this group was 17.1 months with a 1 and 2 year actuarial survival of 62% and 38%, respectively. In the 33 cases without a complete response the median survival was 6.5 months with a 1 and 2 year actuarial survival of 22% and 11%, respectively.

Photodynamic therapy of malignant brain tumours can be carried out with acceptable risk. Good responses appear to be related to adequate light delivery to the tumour.