MAP17 Expression in Colorectal Cancer Is a Prognostic Factor for Disease Recurrence and Dismal Prognosis Already in Early Stage Disease

<b><i>Background:</i></b> Disease recurrence in colorectal cancer constitutes a major cause of significant cancer-associated morbidity and mortality. MAP17 is a small protein, and its overexpression in malignant tumors has been correlated with aggressive tumor phenotypes. The aim of the present study was to investigate the expression patterns of MAP17 in colorectal cancer specimens and to assess its clinical significance. <b><i>Patients and Methods:</i></b> Surgical specimens of 111 patients with primary resectable colorectal cancer constituted the study population. Expression of MAP17 was assessed by immunohistochemistry, and the results were correlated with clinical and survival data. <b><i>Results:</i></b> MAP17 was expressed in cancer cells and endothelial cells of tumor blood vessels. Expression of MAP17 more than 10% was correlated with advanced disease stage (<i>p</i> &#x3c; 0.001), higher T classification (<i>p</i> = 0.007), the presence of lymph node metastasis (<i>p</i> &#x3c; 0.001), vascular (<i>p</i> = 0.013) and perineural invasion (<i>p</i> = 0.012). Patients exhibiting MAP17 expression of more than 30% in cancer cells compared to those expressing MAP17 less than 10% demonstrated a significantly worse 3-year progression-free survival (35.2 vs. 91%, <i>p</i> &#x3c; 0.001) and 5-year overall survival (40.8 vs. 91%, <i>p</i> &#x3c; 0.001). Cox regression analysis confirmed MAP17 expression of more than 30% as a prognostic marker of progression free survival (HR 0.136, 95% CI = 0.056–0.329, <i>p</i> &#x3c; 0.001) and overall survival (HR 0.144 [95% CI) = 0.049–0.419, <i>p</i> &#x3c; 0.001) independent of other clinicopathological characteristics. Statistically significantly worse 3-year progression-free survival and 5-year overall survival was demonstrated in the subgroup analysis of patients with early stage cancer only and high expression of MAP17. <b><i>Conclusions:</i></b> High MAP17 expression in patients with colorectal cancer is a significant risk factor for cancer-associated morbidity and mortality already in early stage disease.