ALDH1 expression indicates chemotherapy resistance and poor outcome in node-negative rectal cancer.

The cancer stem cell marker aldehyde dehydrogenase 1 (ALDH1) associates with treatment resistance and adverse outcome in several human cancers. We studied ALDH1 expression in rectal cancer, with special emphasis on its association with treatment response and disease outcome. Immunohistochemical staining for ALDH1 was conducted for 64 biopsies and 209 operative samples from rectal cancer patients treated with short- (n = 89) or long-course (n = 46) (chemo)radiotherapy plus surgery, or with surgery only (n = 74). The staining results were compared to clinicopathological variables, tumor regression grade (TRG) and disease outcome. Nuclear ß-catenin expression pattern was analyzed from 197 operative samples. Positive ALDH1 expression was present in 149 operative samples (71%), correlating with deficient nuclear ß-catenin regulation (P = .018). In a pairwise comparison of respective biopsy and operative samples, ALDH1 expression remained stable or increased after preoperative (chemo)radiotherapy in most of the cases, while it decreased in few cases only (P = .02 for positive/negative category; P <.001 for intensity). ALDH1 expression did not, however, relate to tumor regression grade. In node-negative rectal cancer, ALDH1 expression was an independent predictor of short disease-free and disease-specific survival (P = .044; P = .049), specifically among patients treated with adjuvant chemotherapy. We conclude that ALDH1 associates with deregulated ß-catenin signaling, supporting the role of ALDH1 in rectal cancer stemness. ALDH1 expression relates to poor outcome in early stage rectal cancer, a group where new prognostic tools are particularly needed, and may indicate chemo- and radioresistance.

Securin identifies a subgroup of patients with poor outcome in rectal cancer treated with long-course (chemo)radiotherapy.

BACKGROUND: Securin is an oncogene with functions in cell proliferation, tumour initiation and progression. Its prognostic value in rectal cancer is somewhat unknown. Accordingly, we studied securin expression together with Ki-67 in rectal cancer in relation to preoperative (chemo)radiotherapy (RT) and disease outcome. MATERIAL AND METHODS: Biopsies (n = 65 for securin; n = 57 for Ki-67) and operative specimens (n = 207) from 211 patients treated with short-course RT (n = 87), long-course RT (n = 54) or surgery only (n = 70) were studied with immunohistochemistry (IHC) for securin and Ki-67 expression. In the long-course RT group, 45 patients received chemotherapy (5-fluorouracil or capecitabine) concomitantly with RT. The results of IHC were related to clinicopathological variables, disease outcome and tumour regression grade (TRG) after long-course RT. RESULTS: Both markers showed significant reduction after RT (p < 0.001). No differences in expression was seen in the long-course RT group between the patients with or without concomitant chemotherapy (p = 0.23 for securin; p = 0.31 for Ki-67). Low Ki-67 expression, but not that of securin, in operative specimens was significantly related to excellent TRG (p = 0.02 for Ki-67; p = 0.21 for securin). In univariate survival analysis, excellent TRG predicted longer disease-specific survival (DSS; p = 0.03). In multivariate Cox analysis, high securin expression after long-course (chemo)RT was an independent predictor of shorter DSS (p = 0.036) together with patient age (p = 0.043) and disease recurrence (local or distant; p = 0.009), whereas no similar appearance was seen in other treatment groups. CONCLUSION: Securin expression in rectal cancer is significantly reduced after RT. High securin expression and poor TRG after long-course (chemo)RT are indicators of unfavourable disease outcome.