Photodynamic therapy using 5-aminolaevulinic acid for oesophageal adenocarcinoma associated with Barrett's metaplasia

Photodynamic therapy (PDT) is a novel technique for local endoscopic treatm ent of gastrointestinal neoplasia. Current photosensitisers for PDT may cau se prolonged skin phototoxicity. 5-Aminolaevulinic acid (ALA), a precursor of the photosensitiser protoporphyrin IX (PpIX), is more acceptable because of its short half-life and preferential accumulation in mucosa and mucosal tumour. We have treated 12 patients, median age 73 years (range 55-88) wit h oesophageal adenocarcinoma arising from Barrett's metaplasia (two carcino mas-in-situ, grade 0; 10 carcinomas, grade l-llA based on endoluminal ultra sound in two and CT scanning in 10 patients). ALA (60 and 75 mg/kg body wei ght) was given orally in two or five equally divided doses. The PpIX distri bution in stomach, normal oesophagus, Barrett's mucosa and carcinoma was me asured by quantitative fluorescence photometry. PDT was performed using las er light (630 nm) delivered via a cylindrical diffuser 4-6 h after the firs t dose of ALA. The patients received one to four sessions of PDT. PpIX accu mulation in the mucose was two to three times that in the lamina propria, T he differential distribution between carcinomatous and normal oesophageal m ucosa was less marked (carcinoma:normal mucosa ratio = 1.4). Higher doses o f ALA increased PpIX accumulation in all tissues but did not increase the d ifferential PpIX distribution between tumour and normal oesophageal mucosa. After PDT using ALA (ALA/PDT), all mucosa showed superficial white necroti c changes and the histology confirmed fibrinoid necrosis. One patient with carcinoma-in-situ had the tumour eradicated after one treatment with no rec urrence at 28 months. Another patient with a small T1 tumour required four ALA/PDT treatments, and died of other disease after 36 months. There was no evidence of recurrence. The tumour bulk in the other carcinomas was not si gnificantly reduced. ALA/ PDT has a potential for the eradication of small tumours but careful patient selection with endoluminal ultrasound is needed when using ALA/PDT to treat oesophageal cancer. (C)1999 Elsevier Science S .A. All rights reserved.