Pim-3 as a potential predictor of chemoradiotherapy resistance in locally advanced rectal cancer patients

Approximately 30% of locally advanced rectal cancer patients might not benefit from chemoradiotherapy; however, the response to neoadjuvant chemoradiotherapy in these cases is difficult to predict. Pim-3 is a member of the provirus integration site for a moloney murine leukemia virus family of proteins that contributes to cell proliferation, survival, and chemotherapy resistance. Therefore, the relationship between Pim-3 expression and response to neoadjuvant chemoradiotherapy in rectal cancer patients is important to evaluate. 175 rectal cancer patients who underwent neoadjuvant treatment enrolled in this study. The relationship between Pim-3 expression on immunohistochemical analysis of rectal cancer tissue, which was obtained before treatment, the response to chemoradiotherapy and survival was investigated. The patients with no Pim-3 expression were more likely to achieve a pathologic complete response to chemoradiotherapy than patients with Pim-3 expression (P = 0.001). Cox multivariate analysis showed that the significant prognostic factors were Pim-3 expression (P = 0.003) and the number of neoadjuvant chemotherapy cycles (P = 0.005) for overall survival. Neoadjuvant chemotherapy cycles (P = 0.007), adjuvant chemotherapy cycles (P = 0.004) and pathology types (P = 0.049) were significant prognostic factors for disease-free survival. Pim-3 is a potential predictive biomarker for the response of rectal cancer to chemoradiotherapy.