L-type amino-acid transporter 1 expression predicts the response to preoperative hyperthermo-chemoradiotherapy for advanced rectal cancer

Aim: To evaluate whether expression of L-type amino acid transporter 1 (LAT1) in pretreatment rectal cancer biopsies is predictive of tumour response to neoadjuvant hyperthermo-chemoradiotherapy (HCRT). Patients and Methods: Forty-four patients with rectal adenocarcinoma who received neoadjuvant HCRT were investigated. LAT1 expression was immunohistochemically evaluated using pretreatment biopsies. The operation was performed after 2-3 months following HCRT and each resected specimen was graded by the histological criteria of the Japanese Classification of Colorectal Carcinoma. Results: A positive LAT1 expression was recognized in 50.0% (22144) of patients. Resected specimens were divided into 2 groups according to the histological grading criteria: good response (n=29) and poor response (n=15). LAT1-negative tumours had an 81.8% probability of good response and 18.2% probability of poor response. LAT1 expression showed marginally significant association with response to HCRT (p=0.05). Conclusion: LAT1 may be a useful predictive marker of response to HCRT in rectal cancer.