The prognostic significance of the expression of monocarboxylate transporter 4 in patients with right‐ or left‐sided colorectal cancer

Aim Monocarboxylate transporter 4 (MCT4) is a proton pump that exchanges lactate through the plasma membrane. The present study investigated the clinical significance of the expression of MCT4 in patients with right‐ or left‐sided colorectal cancer (CRC). Methods Surgical specimens from 237 CRC patients were immunohistochemically stained with polyclonal anti‐MCT4 antibodies. The relationships among the MCT4 expression, the clinicopathological factors, and the prognosis were evaluated. Results Thirty‐six (62.1%) of 58 patients with right‐sided CRC and 95 (53.1%) of 179 patients with left‐sided CRC showed the high expression of MCT4. The MCT4 expression was significantly correlated with gender and lymph node metastasis in patients with right‐sided CRC, and size, depth of invasion, distant metastasis, and tumor‐node‐metastasis stage in patients with left‐sided CRC. A univariate analysis demonstrated that the expression of MCT4 was a significant prognostic factor in both right‐ and left‐sided CRC patients. A multivariate analysis demonstrated the expression of MCT4 was a significantly independent prognostic factor in patients with left‐sided CRC, but not in those with right‐sided CRC. Conclusions Our results suggest that the high expression of MCT4 is a useful marker for tumor progression and a poor prognosis in CRC patients, especially those with left‐sided CRC.