Effect of photodynamic therapy on recurrent pituitary adenomas: clinical phase I/II trial - an early report

Pituitary adenomas, although histologically benign, are not always curable by surgery alone, principally because of dural infiltration, as well as the ir peculiar anatomical location. Radiotherapy has been employed as an adjuv ant therapy to address residual disease with favourable results. This appro ach is, however, not without side effects, and it cannot be repeated. We ar e therefore investigating the effectiveness of photodynamic therapy (PDT) o n recurrent pituitary adenomas in humans. This study details the protocol a pplied to 12 patients with recurrent pituitary adenomas, which involved sys temic administration of photosensitizer (Photofrin) followed, after a perio d of 24-48 h, by intraoperative illumination of the tumour bed using 630 nm laser light. The primary end points were visual, endocrine and radiologica l improvement. The incidence of side effects was also monitored. The longes t follow-up is 2 years. Most patients suffering from visual acuity or field defects have shown improvement when followed for 12 months or more. Three patients showed complete recovery of their visual fields. All those who pre sented with functional adenomas have shown reduction in their hormone level s. Tumour volume, relative to the preoperative size, was 122, 87, 66, 60 an d 46% at 4 days, and 3, 6, 18 and 24 months, respectively. One patient deve loped severe skin photosensitization due to early exposure to direct sunlig ht and three others displayed minor skin reactions. There was no treatment- related mortality or morbidity. One patient (operated transcranially) devel oped hemiparesis postoperatively, which recovered completely. We think this is unrelated to the treatment. This prospective study demonstrates that PD T may be safely applied to the pituitary fossa by the trans-sphenoidal rout e and indicates the need for a randomized, controlled trial in order to est ablish its therapeutic potential.