Photodynamic diagnosis of breast tumours after oral application of aminolevulinic acid

Summary Photodynamic diagnosis is of increasing interest for diagnosis in oncology. It is based on a more intense incorporation of afluorescent dye in tumours compared to normal tissue. As a feasibility study we investigated the effectiveness of oral application of5-aminolevulinic acid for photodynamic diagnosis of human primary mammary tumours. The study included 16 patients with palpable breasttumours. Aminolevulinic acid was administered at a concentration of 40 mg kg –1 bodyweight 150–420 min prior to tumourectomy.Intraoperatively blue light (405 nm) was applied to the operation site. Sections of the excised tumour and some lymph nodes were preparedand analysed with a fluorescent microscope. All primary mammary tumour tissues showed significantly higher fluorescence intensity thansurrounding normal mammary tissue. Fluorescence of the mammary tumours could also be discriminated macroscopically andintraoperatively. Fluorescence intensity in nonmetastatic lymph node tissue was higher in 2 out of 3 patients than in primary t umour tissue. Byphotodynamic diagnosis using aminolevulinic acid we were able to reliably distinguish primary mammary tumours from normal mammarytissue microscopically and macroscopically in all our patients. We suggest that photodynamic diagnosis with aminolevulinic acid for breasttumours should be further investigated and developed for intraoperative use and may well be a simple tool for better intraopera tive diagnosisand recognition of tumour margins. We hypothesize that lymph node metastasis of breast tumours will not be detectable by this method.© 2001 Cancer Research Campaign http://www.bjcancer.comKeywords: aminolevulinic acid; photosensitizer; photodynamic diagnosis; photodynamic therapy; breast tumours; axillary lymph nodes 33