Recurrence and survival predictive value of phenotypic expression of Bcl-2 varies with tumor stage of colorectal adenocarcinoma

Abstract

Although decreased or lack of expression of Bcl-2 has been correlated with advanced tumor stage and shortened patient survival in colorectal cancer (CRC), its value in predicting the recurrence has not been well explored. Therefore, we assessed the usefulness of phenotypic expression of Bcl-2 in non-Hispanic Caucasian patients with CRCs in identifying risk of recurrence. Archival tissues of 92 Stage II and 66 Stage III primary CRCs were evaluated for immunohistochemical expression of Bcl-2. None of these patients received either pre- or post-surgical adjuvant therapies. Kaplan-Meier and Cox proportional hazards methods were used to estimate the rates of recurrence and survival according to Bcl-2 expression. Decreased expression of Bcl-2 was associated with an increased rate of recurrence in patients with Stage II CRCs (5-year log-rank test P=0.0015; Hazard Ratio (HR)=3.90, 95%C.I.:1.55-9.77) but not with Stage III CRCs (5-year log-rank test P=0.6058; HR=1.07, 95%C.I.:0.47-2.45) after adjusting for other demographic and clinicopathological features. Furthermore, decreased expression of Bcl-2 was an indicator of short survival in patients with Stage II CRCs but not with Stage III CRCs. Thus, decreased or lack of Bcl-2 expression in primary CRCs may serve as a molecular biomarker of high risk of recurrence for Caucasian patients with Stage II CRCs. These findings might be useful in identifying biologically aggressive phenotypes of Stage II CRCs, and may aid the oncologist in designing maximally appropriate therapeutic regimens.

Fig. 1

Bcl-2 expression in primary colorectal adenocarcinomas. The staining intensity of Bcl-2 expression was from very weak (A), low (B) to strong (C). Bcl-2 expression was primarily in the cytoplasm (arrows with small heads) of the malignant cells. A strong Bcl-2 expression pattern was observed in lymphocytes (arrows with large heads).

Fig. 2

Kaplan-Meier curves and log-rank tests to assess the risk of recurrence based on the Bcl-2 expression status and tumor stage in Caucasians with CRCs: Significant difference in rate of recurrence was observed between stage II and stage III CRC cases (A). Deceased or lack of Bcl-2 expression was significantly associated with an increased rate of recurrence only in patients with stage II (B) but not in Stage III (C) CRCs.