Study Of Association Between HER-2,EZH2 Expression And Prognosis In Rectal Cancer

SECTION ⅠASSOCIATION OF HER-2 EXPRESSION AND THE PROGNOSIS IN RECTAL CANCERBackgroundRectal cancer is one of the leading causes of cancer related deaths in the world. Pathologic staging is used to predict survival. However, there is uncertainty concerning the difference in prognosis with patients who have same pathologic stage. Therefore, it is quite important to find one biologic marker to predict the prognosis and to select patients for advanced treatment in rectal cancer. The frequency of HER-2 and the role of prognosis in rectal cancer remains controversial. The aim of this study was to determine the status of HER-2 and the predicting role of clinical outcome in a large multicenter cohort of rectal cancer patients undergoing surgery directly.Materials and MethodsThe clinical and pathological features were reviewed retrospectively for the purpose of the study from January 2007 to December 2009. All patients were diagnosed with primary rectal adenocarcinoma by rectoscopy. Preoperative diagnosis was established by a series of examination. The patients took surgery directly without any preoperative anticancer treatment.Tumor samples were collected from resected specimens. The HER-2 status was assessed by immunohistochemistry. HER-2 expression was evaluated by two parameters:the intensity of staining and the percentage of stained cancer cells. The parameters were used to determine the IHC score according to the ToGA trial:absent (IHC 0), no staining; low (IHC1+), faint intensity in 10% or more; moderate (IHC2+), moderate intensity in 10% or more; high (IHC3+), strong intensity in 10% or more of cancer cells.HER-2 gene amplification was performed to confirm HER-2 expression in all samples with an IHC score of 2+ by the fluorescence in situ hybridization (FISH). A specimen with a HER-2/CEP17 ratio of 2.0 or more in tumor cells was classified as HER-2 amplification.ResultsA total of 717 rectal cancer patients were included in this study. There were 201 cases classified as IHC score 0,193 cases classified as IHC score 1+,224 cases classified as IHC score 2+, and 99 cases classified as IHC score 3+. HER-2 gene amplification was detected in 16 cases of 223 patients with IHC score 2+. In all,99 cases as IHC3+ and 16 cases IHC 2+ plus gene-amplified were determined as HER-2 positive. The positivity in rectal cancer is 16%. Correlation analyses showed a lack of significant association of HER-2 positivity with any clinicopathologic parameters such as sex, age, differentiation, pT or pN.Local recurrence occurred in 128 (17.8%) patients and distant metastasis occurred in 206 (28.7%) patients.26 cases in 115 HER-2 positive patients had local recurrence while 102 cases in 602 HER-2 negative patients did (p=0.146). Compared with HER-2 negative patients, it seemed that HER-2 positive tumors might be more likely to have distant metastasis(36.5% vs 64.2%, p=0.007).The 5-year disease free survival (DFS) of 115 patients with HER-2 positive status was significantly shorter than that of 602 patients with HER-2 negative status (52.2%vs 69.6%, p<0.001). HER-2 negative patients had significant better overall survival (OS) as compared with HER-2 positive patients (73.9% vs 63.5%, p=0.013). In the subgroup of early rectal cancer (T1 or T2 without node metastasis and distant metastasis), the HER-2 status was also a poor predictor for 5-year DFS (p=0.047)and 5-year OS (p=0.032). In multivariate analysis, HER-2 was a prognostic factor for 5-year DFS (HR=1.929,95% CI 1.425-2.613, p<0.001) and for 5-year OS (HR=1.625; 95% CI 1.155-2.285, p=0.005).Conclusion115 cases in 717 patients (16%) as IHC3+or IHC 2+plus gene-amplified were determined as HER-2 positive. HER-2 overexpression was not associated with any clinicopathologic parameters. HER-2 may predict distant metastasis but not local recurrence. In term of clinical outcome, HER-2 positivity were significantly associated with poor 5-year disease-free survival and 5-year overall survival. Our results suggested that HER-2 overexpression might be a poor predictor for survival in rectal cancer. To further validate the role of HER-2 protein for anti-HER-2 therapy, clinical trials are needed115 cases in 717 patients (16%) as IHC3+or IHC 2+plus gene-amplified were determined as HER-2 positive. HER-2 overexpression was not associated with any clinicopathologic parameters. HER-2 may predict distant metastasis but not local recurrence. In term of clinical outcome, HER-2 positivity were significantly associated with poor 5-year disease-free survival and 5-year overall survival. Our results suggested that HER-2 overexpression might be a poor predictor for survival in rectal cancer. To further validate the role of HER-2 protein for anti-HER-2 therapy, clinical trials are neededSECTION ⅡTHE PROGNOSTIC ROLE OF EZH2 EXPRESSION IN RECTAL CANCER PATIENTS TREATED WITH NEOADJUVANT CHEMORADIOTHERAPYBackgroundNeoadjuvant chemoradiotherapy (nCRT) combined with surgery has been implemented as a standard treatment strategy in locally advanced rectal cancer (LARC). However, there is a wide spectrum of response to nCRT. The aim of this study was to determine whether enhancer of zeste homologue 2 (EZH2) expression could predict response to nCRT and outcomes for patients in LARC.MethodThe clinicopathological characteristics were reviewed retrospectively for the purpose of the study. All patients were diagnosed with primary rectal adenocarcinoma confirmed by rigid rectoscopy. TNM stages were reported according to the American Joint Committee on Cancer (AJCC). T3 or T4 without distant metastasis were included in the study.112 patients received concurrent chemotherapy and radiotherapy followed by surgery. In brief, patients underwent whole pelvis preoperative radiotherapy with a dose of 50.4 Gy in 28 fractions using three-dimensional conformal irradiation or four-field box technique. Concurrent chemotherapy regimens include continuous infusion of 5-fluorouracil ± oxaliplatin or capecitabine ± oxaliplatin. Four to six weeks after the completion of nCRT, total mesorectal excision (TME) was performed.Pathologic TNM staging was performed on the surgical specimens to assess tumor down-staging according to the current classification. Tumor response was also evaluated using the tumor regression grade (TRG) system proposed by Dworak et al.Tumor samples were collected from pretreatment tumor biopsies in 112 patients who received nCRT. The EZH2 and Ki-67 status was assessed. The study examined the EZH2 expression in 112 biopsies by immunohistochemistry. The associations between EZH2 and clinical characters were analyzed.ResultsEZH2 expression in biopsy tissue was significantly related to increased tumor cell proliferation, as assessed by Ki-67 expression with a cutoff value of 37%(p<0.001). High EZH2 expression was correlated closely with low differentiation (p=0.029), high CEA level (p=0.041), T4 status (p=0.011) and node metastasis (p=0.045).A comparison of pretreatment staging results and histopathologic diagnosis after surgery revealed AJCC down-staging in 52.7% patients (n=59). Tumor regression grade analysis showed good response (TRG 3 and TRG4) in 47.3% patients (n=53). By univariate and multivariate analysis, we observed low EZH2 expression could reliably and independently predict the good response to nCRT (p=0.026 and p=0.023) and down-staging (p=0.021 and p=0.027). Moreover, cN was also kept in the model as a predictive factor for good tumor response (p=0.018) and down-staging (p=0.025).EZH2 status, cN, cT, pathological tumor status (pT) and pathological node status (pN) were found to be significantly correlated with 5-year DFS and 5-year OS in univariate analysis. In univariate analysis, high EZH2 expression was significantly associated with poor 5-year disease-free survival (p=0.025) and 5-year overall survival (p=0.032). In multivariate analysis, EZH2 was a prognostic factor for 5-year DFS (HR=2.287; 95% CI 1.137-4.602, p=0.020) but not for 5-year OS (HR=2.182; 95% CI 0.940-5.364, p=0.069).ConclusionOur study revealed that low EZH2 expression in biopsy tissue might be a useful predictive factor of good tumor response to nCRT and longer 5-year DFS in patients with LARC. However this is a relatively small retrospective study, to further validate the role of EZH2 in rectal cancer, large consistent cohort studies are needed.