FBI-1 expression in relation to clinicopathological variables in rectal cancers with a Swedish clinical trial of preoperative radiotherapy.

Abstract

e15102 Background:FBI-1 is a recently characterized proto-oncoprotein of the POZ domain Krüppel-like (POK) family of transcription factors. Although several studies provide the evidence that FBI-1 is an important gene regulator in CRC, no analysis of any correlation between FBI-1 expression and preoperative radiotherapy (RT) has been studied in rectal cancers. Methods: This study included the patients with rectal cancer that participated in a Swedish clinical trial of preoperative RT between 1987 and 1990. Patients were divided into preoperative RT (62) and non-RT (77) groups. Applying immunohistochemstry, we detected FBI-1 expression in 118 normal mucosa, 139 primary rectal cancers, and 45 lymph node metastases, and analyzed its relationship with clinicopathological features and RT response. Results: FBI-1 was detected both in the cytoplasm and nucleus, and the cytoplasmic staining was up-regulated compared with normal mucosa both in non-RT and RT groups (74.0% vs. 17.7%, p < 0.001; 69.4% vs. 41.1%, p = 0.002), however, the nuclear staining was down-regulated compared with normal mucosa both in non-RT and RT groups (22.1% vs. 75.8%, p < 0.001; 35.5% vs. 83.9% p < 0.001). Both cytoplasmic and nuclear staining were no difference between the non-RT and RT groups (74.0% vs. 69.4%, p = 0.542; 22.1% vs. 35.5%, p = 0.080, respectively). So we combined the non-RT and RT group together for further analysis. Nuclear staining of FBI-1 was positively with TNM stage and distance recurrence, it showed higher expression in III+ IV stage than that in I+II stage (41.0% vs. 17.9%, p = 0.003). The patients with distance recurrence showed higher FBI-1 expression than that with no distance recurrence (39.7% vs. 19.8%, p = 0.010). In stage I, II and III patients, higher nuclear FBI-1 in primary cancer showed worse disease free survival (HR: 1.934; 95%CI: 1.055-3.579, p = 0.033) and overall survival (HR: 2.174; 95%CI: 1.102-4.290; p = 0.025) independent of gender, age, growth pattern, differentiation and RT. Conclusions: Higher nuclear FBI-1 is related with later TNM stage, distance recurrence, and worse prognosis, it can be used as a potential diagnostic and prognostic biomarker in rectal cancer.