Biochemical aspects of ALA-PDT : basic mechanisms and optimization for the treatment of Barrett's oesophagus

From the late 1970s, the incidence of adenocarcinoma of the oesophagus has increased more rapidly than that of any other cancer in the western world (Blot et al., 1991). Adenocarcinoma of the oesophagus usually occurs in patients who have Barrett's oesophagus (Cameron et ai., 1995). Barrett's oesophagus is a complication of chronic gastro(duodeno)oesophageal reflux (Hamilton, 1985). The true prevalence of Barrett's oesophagus is unknown. In patients with long-standing gastro-oesophageal reflux disease the prevalence of Barrett's oesophagus is at least 10% (Winters et ai., 1987). However, an autopsy study performed by Cameron et ai. suggested that for every patient discovered during investigation for reflux symptoms there are 20 patients in the general population with undiagnosed Barrett's oesophagus (Cameron et al., 1990). Prospective studies reported a 30-125 times higher risk of developing adenocarcinoma in patients with Barrett's oesophagus than in the general population (Cameron et ai., 1985; Drewitz et al., 1997; Hameeteman et ai., 1989; Spechler et ai., 1984; van der Veen et al., 1989). Barrett's oesophagus is therefore considered to be a relatively common lesion that has a significant malignant potential.