Imunoexpression of Ki-67 and p53 in Rectal Cancer Tissue After Treatment with Neoadjuvant Chemoradiation

Molecular Predictors of Response to Neoadjuvant Chemoradiation for Rectal Cancer

OBJECTIVES

To determine whether the expression of specific molecular markers in the rectal cancer biopsies prior to treatment, can correlate with complete tumor response to chemoradiotherapy (CRT) as determined by the pathology of the surgical specimen.

METHODS

We retrospectively examined pretreatment rectal biopsies of patients aged 18 years or older with locally advanced rectal cancer who had been treated with neoadjuvant CRT and surgical resection in our tertiary-care, university-affiliated medical center, between January 2001 and December 2011. Samples were analyzed for expression of B-cell lymphoma 2, P53, Ki67, epidermal growth factor receptor (EGFR), vascular endothelial growth factor receptor, and the tumor regression grade after CRT and radical surgery.

RESULTS

Forty-seven patients were included in the final analysis. Main outcome measures were the correlation between the expression of the molecular markers tested in the pretreatment biopsy, and complete tumor response. Complete pathologic response after CRT was attained in 27% of the patients. Percentage of cells expressing EGFR in the pretreated biopsies of patients having complete pathologic response after CRT and surgery was 33.08±7.87% compared to 19±15.36% (P=0.38), 6.66±2.83% (P<0.003), and 12.5±4.93% (P=0.033) in patients with partial response and tumor regression grades of 2, 3, and 4, respectively. The other molecular markers tested in the pretreatment biopsy did not corresponded with complete pathologic response.

CONCLUSIONS

EGFR expression pattern in the pretreatment biopsies of rectal tumors can assist in identifying patients who will benefit from neoadjuvant CRT.

P21 and CD166 as predictive markers of poor response and outcome after fluorouracil-based chemoradiotherapy for the patients with rectal cancer

Background

Pre-operative chemoradiotherapy (CRT) is the standard treatment in clinical stage T3/4 or node positive rectal cancer. However, there are no established biomarkers that can predict the pathological response and clinical outcome to CRT.

Methods

Immunohistochemical staining was performed in tissue arrays constructed from core tissue specimens taken before treatment and from operative specimens from 112 patients who received 5-FU based pre-operative CRT and surgery. Expression of Ki67, TS, BAX, EpCAM, p53, p21, EGFR, CD44, CD133, CD166, HIF1α and ALDH1 were assessed and correlated with tumor regression grades and disease free survival.

Results

Of the 112 patients (M/F 74/38, median age: 62), 20 (17.9%) patients achieved pathologic complete remission (pCR). In analyzing the associations between marker expressions and tumor regression grades, high p21 expression at the pretreatment biopsy was significantly associated with non-pCR (p = 0.022) and poor disease free survival (median DFS - low vs high p21: 75.8 vs 58.1 months, p = 0.002). In the multivariate analysis, high p21 expression level at the pre-treatment biopsy was significantly associated with poor DFS (p = 0.001, HR 6.14; 95% CI 2.03, 18.55). High CD166 expression level at the pretreatment biopsy was also associated with poor DFS (p = 0.003; HR 5.61; 95% CI 1.81, 17.35).

Conclusion

These show high p21 and CD166 expression at the pretreatment biopsy were associated with tumor regression and poor prognosis in patients treated with 5-FU based CRT. Larger, prospective and functional studies are warranted to determine the role of p21 and CD166 as predictive biomarker of response to CRT.