PDT of the endometrium using ALA

There is a widely recognized need for new approaches to effect endometrial ablation as an alternative to hysterectomy for treatment of menorrhagia. Photodynamic therapy (PDT) offers one such approach. We have investigated the use of 5-aminolaevulinic acid (ALA)-based PDT of the endometrium in model systems and in a series of patients. In all of this work, the ALA was administrated directly into the uterine cavity to reduce any possibility of systemic photosensitization. In a series of experiments in perfused ex vivo uteri, ALA was introduced into the cavity and protoporphyrin formation was measured in the endometrium, the underlying myometrium and the perfusate. ALA transfer into the perfusate was also measured. This work demonstrated that protoporphyrin formation in the endometrium was approximately ten fold that in the underlying myometrium and that systemic photosensitization would be unlikely to result form transfer of administered ALA from the uterus into the circulation. Similar results were found in studies carried out in vivo, where ALA was administered to patients scheduled for hysterectomy. Using a specially designed light source, the first patients have now been treated by giving intrauterine ALA followed by laser light. Two series of treatments - 10 in all - have been carried out. Eight patients have one year follow up. A reduction in measured menstrual blood loss was demonstrated in all but one patient. Complete symptomatic relief was obtained in tow women who did not require further treatment.