Aldehyde dehydrogenase isoform 1 (ALDH1) expression as a predictor of radiosensitivity in laryngeal cancer

Aldehyde dehydrogenase isoform 1 (ALDH1) has been shown to be a marker of cancer stem cells (CSCs). These stem cells may be responsible for tumour perpetuation as well as local and distant invasion. Several studies have shown that CSCs are more chemoradiotherapy (CRT)-resistant and may be responsible for tumour recurrence. Other studies, in contrast, have found ALDH1 expression to be indicative of a better prognosis. We retrospectively evaluated 84 patients diagnosed and treated for laryngeal cancer between 2006 and 2011. All patients underwent curative-intent radiotherapy or CRT at our institution. 57 of the 84 tumour samples contained sufficient material for ALDH1 assessment. ALDH1 expression was detected in 17.5 % (10/57) of the tissue samples. None of the tumours from stage I patients tested positive for ALDH1. The relapse rate in ALDH1 + patients was 10 versus 51.2 % for ALDH1-. No differences in overall survival were observed between the groups; however, disease-free survival was 90 % for the ALDH1 + group versus 48.9 % for ALDH1- patients (p = 0.034). The patients in this study with ALDH1 + tumours had better outcomes than their counterparts with ALDH1- tumours. This finding suggests that not all CSCs are resistant to conventional cancer treatments. It may also imply that new methods of correctly identifying these cells are needed.