Fluorescence hysteroscopy using 5-aminolevulinic: a descriptive study

BACKGROUND AND OBJECTIVES

To assess the feasibility of fluorescence hysteroscopy following topical ALA application and to describe the optical appearance of normal and neoplastic endometrium.

STUDY DESIGN/MATERIALS AND METHODS

Fifty-four patients scheduled for routine hysteroscopy and D&C were assigned to the study group using topically applied ALA. Two milliliters of a 2% 5-ALA-solution at pH = 4.0 (ASAT AG/Zug, Switzerland) was administrated into the uterine cavity 4 hours before fluorescence hysteroscopy, using a STORZ-D-Light (Tuttlingen, Germany) system. Hysteroscopic findings were compared to the histological diagnosis of hematoxylin & eosin (H&E) stained sections. In the study group, 60 histological specimens were taken (47 materials of curettage and 13 targeted biopsies). The percentage of fluorescence positive patients was calculated.

RESULTS

The rate of fluorescent endometrial samples was low in atrophic endometrium 1/16 (6.2%). Endometrial carcinoma were diagnosed in two patients. Both cases exhibited selective and intense PpIX-mediated red fluorescence. Fluorescence hysteroscopy could not differentiate between hyperplastic areas with or without atypia. Minimal uterine cramps or discomfort following ALA instillation were complained by 30 (56%) patients, no pain was indicated by 24 patients (44%).

CONCLUSIONS

Fluorescence hysteroscopy following intrauterine application of ALA is feasible. Cancerous, hyperplastic, and secretory endometrial tissue showed high red fluorescence.

Rodent fibroblast model for studies of response of malignant cells to exogenous 5-aminolevulinic acid

All nucleated mammalian cells synthesize protoporphyrin IX (PpIX) when exposed to exogenous 5-aminolevulinic acid (ALA). The response to exogenous ALA under standard conditions (the ALA phenotype) is characteristic for each cell type. Significantly more PpIX accumulates in malignant and premalignant cells than in the normal cells from which they were derived. A rodent fibroblast model was developed to study the mechanisms responsible for this phenomenon. Exogenous ALA induced the accumulation of substantial concentrations of PpIX in fibrosarcoma cells, and in immortalized fibroblasts transfected with the oncogene c-myc, IGF-1 receptor, IGF-1 and its receptor, v-fos, v-raf, v-Ki-ras, v-abl, or polyomavirus middle T antigen with G418 resistance selection. Much lower concentrations of PpIX accumulated in primary fibroblast cultures, in immortalized fibroblast cell lines, and in immortalized fibroblasts transfected with the G418-resistance gene only. The mechanisms responsible for the increased accumulation of ALA-induced PpIX by transformed cells (the malignant ALA phenotype) therefore appear to be closely linked to the mechanisms responsible for malignant transformation. Identification of the nature of that linkage may lead to new approaches to cancer therapy.