Abstract
Aim: the response of rectal adenocarcinoma to neoadjuvant therapy is variable. Accurate prediction of response would enable selective administration of therapy. The enzyme glutathione S-transferase Pi (GSTP1) has been shown to influence response to therapy in some solid tumours. Few data are available for rectal cancer.
Method: GSTP1 levels in rectal adenocarcinoma and adjacent normal mucosa were quantified before and after exposure to neoadjuvant therapy. Venous blood samples and biopsies of normal rectal mucosa and tumour were prospectively obtained from patients with primary rectal cancer. Patients were stratified by exposure to neoadjuvant therapy or surgery alone. GSTP1 was quantitatively measured using an enzyme-linked immunosorbent assay.
Results: ninety two (54 male; median age 68 years) patients were recruited. GSTP1 was significantly greater in rectal adenocarcinoma compared with matched normal mucosa [median 6.59 vs. 4.57 μg/mg, p<0.001]. Tumour GSTP1 was significantly lower in the therapy group compared with unmatched samples from the no therapy group [median 4.47 vs. 7.76 μg/mg, p<0.001].
Conclusion: GSTP1 is increased in rectal adenocarcinoma compared with adjacent normal mucosa. It decreases following neoadjuvant therapy.
© 2012 The Authors Colorectal Disease © 2012 The Association of Coloproctology of Great Britain and Ireland
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