PHOTODYNAMIC THERAPY AS ADJUVANT THERAPY IN SURGICALLY TREATED PLEURAL MALIGNANCIES

Five patients with a pleural malignancy (four malignant mesotheliomas and one localized low grade carcinoid) were treated with maximal surgi cal resection of the tumour followed by intraoperative adjuvant photod ynamic therapy (PDT). The additional photodynamic treatment was perfor med with light of 652 nm from a high power diode laser, and meta-tetra hydroxy phenylchlorin as the photosensitizer. The light delivery to th e thoracic cavity was monitored by in situ isotropic light detectors. The position of the light delivery fibre was adjusted to achieve optim al light distribution, taking account of reflected and scattered light in this hollow cavity. There was no 30-day post-operative mortality a nd only one patient suffered from a major complication (diaphragmatic rupture and haematopericardium). The operation time was increased by a maximum of 1 h to illuminate the total hemithoracic surface with 10 J cm(-2) (incident and scattered light). The effect of the adjuvant PDT was monitored by examination of biopsies taken 24 h after surgery und er thoracoscopic guidance. Significant damage, including necrosis, was observed in the marker lesions with remaining malignancy compared wit h normal tissue samples, which showed only an infiltration with PMN ce lls and oedema of the striated muscles cells. Of the five patients tre ated, four are alive with no signs of recurrent tumour with a follow-u p of 9-11 months. One patient was diagnosed as having a tumour dissemi nation in the skin around the thoracoscopy scar and died of abdominal tumour spread. Light delivery to large surfaces for adjuvant PDT is fe asible in a relatively short period of time (<1 h). In situ dosimetry ensures optimal light distribution and allows total doses (incident pl us scattered light) to be monitored at different positions within the cavity. This combination of light delivery and dosimetry is well suite d for adjuvant treatment with PDT in malignant pleural tumours.