No abstract

555 Background: Rac GTPase activating protein (RacGAP) 1 plays a key role in controlling various cellular phenomena including cytokinesis, transformation and migration. Recently, the clinical significance of RacGAP1 expression has been reported in several malignancies. However, direct association between the RacGAP1 expression and colorectal cancer (CRC) has not been fully investigated. The aim of this study is to elucidate the function and clinical significance of RacGAP1 expression in CRC. Methods: The intrinsic functions of RacGAP1 in CRC cells were analyzed using small interfering RNA (siRNA). We analyzed RacGAP1 mRNA expression in surgical specimens from 193 CRC patients (Cohort 1) by real-time polymerase chain reaction. Then, we validated RacGAP1 protein expression using formalin-fixed paraffin-embedded samples from 298 CRC patients (Cohort 2) by immunohistochemistry. Finally, we evaluated the association between RacGAP1 mRNA and protein expression and clinicopathological data. Results: Reduced RacGAP1 expression by siRNA in CRC cell lines showed significantly decreased cellular proliferation, migration, and invasion. In Cohort 1, RacGAP1 expression in CRC was significantly higher than in adjacent normal mucosa, and increased according to TNM stage progression. High RacGAP1 expression in tumors was significantly associated with progression and prognosis. In Cohort 2, RacGAP1 protein was overexpressed mainly in the nuclei of CRC cells; however, its expression was scarcely observed in normal colorectal mucosa. RacGAP1 protein expression was significantly higher in CRC patients with higher T stage, vessel invasion, and lymph node and distant metastasis. Increased expression of RacGAP1 protein was significantly associated with poor disease-free and overall survival. Multivariate analyses revealed that high RacGAP1 expression was an independent predictive marker for lymph node metastasis, recurrence, and poor prognosis in CRC. Conclusions: Our data provide novel evidence for the biological and clinical significance of RacGAP1 as a potential biomarker for identifying patients with lymph node metastasis and poor prognosis in CRC.

Pretreatment PNI could be useful in evaluating and managing patients with rectal cancer who undergo CRT followed by curative resection.

BACKGROUND: Despite advances in local control of rectal cancer, recurrence in distant organs is still one of the main causes of mortality. Prognostic biomarkers would be valuable for the treatment of patients who have rectal cancer. OBJECTIVE: The aim of our study was to investigate the prognostic impact of lymphocyte-to-monocyte ratio in patients with rectal cancer receiving preoperative chemoradiotherapy, and to clarify the clinical significance of lymphocyte-to-monocyte ratio. DESIGN: Prospectively maintained data of patients with rectal cancer were retrospectively evaluated to clarify the clinical relevance of the lymphocyte-to-monocyte ratio. SETTING: This study was conducted at a single expert center. PATIENTS: A total of 119 consecutive patients with rectal cancer through chemoradiotherapy followed by total mesorectal excision at our institute were enrolled in this study. Eight patients were excluded because of a lack of laboratory data, and finally 111 patients were assessed in this study. MAIN OUTCOME MEASURES: The primary outcome measured was the clinical relevance of the lymphocyte-to-monocyte ratio in patients with rectal cancer receiving chemoradiotherapy. RESULTS: Patients with a low pretreatment lymphocyte-to-monocyte ratio showed poor prognosis significantly both in overall survival and disease-free survival of those with rectal cancer receiving chemoradiotherapy. Multivariate analyses showed that low pretreatment lymphocyte-to-monocyte ratio level, presence of pathological lymph node metastasis (ypN(+)), and high pretreatment serum C-reactive protein level were independent prognostic factors of overall survival and disease-free survival. In addition, time-to-event analysis divided into 2 groups by ypN status showed that low pretreatment lymphocyte-to-monocyte ratio was correlated with poor overall survival and disease-free survival not only in group ypN(–) but also in group ypN(+). LIMITATIONS: The present study had several limitations, including that it was a retrospective observational and single institutional study with Japanese patients. CONCLUSIONS: The combination of lymphocyte-to-monocyte ratio and ypN status can be a predictive marker of poor prognosis and recurrence among patients with rectal cancer undergoing preoperative chemoradiotherapy. See Video Abstract at http://links.lww.com/DCR/A780.