Tetsuro Higuchi

Cyclooxygenase-2 Expression A Significant Prognostic Indicator for Patients With Colorectal Cancer

Purpose: Recent studies have shown that cyclooxygenase (Cox)-2 may be involved in colorectal carcinogenesis. We aimed to determine whether Cox-2 expression in itself can predict outcome of colorectal cancer patient after surgery. In addition, the expression of Cox-1 was also evaluated. Experimental Design: Tissue samples of primary and secondary tumors from 288 patients undergoing surgical resections for colorectal adenocarcinoma were immunohistochemically examined for Cox-2 and Cox-1 expressions. The specimens were graded based on the intensity and extent of staining; then, the correlations between Cox-2 and Cox-1 expressions with clinicopathologic parameters and survival time were analyzed. Results: Expression of Cox-2 was positive in 70.8% of primary tumor, 92.0% of lymph node metastases, 100.0% of hepatic metastases, and was significantly associated with tumor size, depth of invasion, lymph node metastasis, vessels invasion, stage and recurrence. In contrast, Cox-1 was positive in 42.7% of primary tumor, 84.0% of lymph node metastases, 37.5% hepatic metastases, and was associated with only tumor size. Patients with Cox-2–positive tumors had a significant shorter survival time than those with negative tumors did (P = 0.0006 by log-rank test); and, in a multivariate analysis, Cox-2 was an independent prognostic factor (P = 0.0103; relative risk 4.114; 95% confidence interval, 1.397–12.120). Cox-1 status had no statistically effect on patient survival time. Conclusions: Elevated Cox-2 expression, but not that of Cox-1, was significantly associated with reduced survival and recognized as an independent prognostic factor in our cohort of colorectal cancer patients.

PIK3CA mutation is predictive of poor survival in patients with colorectal cancer

The PI3K‐AKT pathway is activated in a variety of human cancers, resulting in disturbance of cell growth, proliferation and survival. Among the factors affecting the pathway, the K‐Ras mutation and PIK3CA mutation are the most common oncogenic alterations in colorectal cancer. We hypothesized that these two mutations are important in activation of the PI3K pathway and colorectal carcinogenesis. In this study, we aimed to examine the influence of PIK3CA mutation and K‐Ras mutation on AKT activation, and to clarify whether PIK3CA mutation, K‐Ras mutation and p‐AKT expression may be used as parameters for predicting prognosis in colorectal cancer. Tissue samples from 158 colorectal cancer patients who underwent surgical resection were examined. The sequences of exon 1 of K‐Ras and exons 9 and 20 of PIK3CA were determined by direct sequencing using genomic DNA extracted from paraffin‐embedded blocks. Activation status of AKT was evaluated by immunohistochemical staining using phospho‐specific AKT antibody (Ser473). Correlation between these factors and clinicopathologic findings/patient survival were examined. As a result, PIK3CA mutation was significantly associated with shorter relapse‐free survival (RFS) in stage II/III patients (p = 0.0216) and shorter disease‐specific survival in all patients (p = 0.0357). In the multivariate analysis, PIK3CA mutation was the only independent and significant prognostic factor for RFS in stage II/III patients (p = 0.0433, HR 2.478). This study revealed the prognostic value of PIK3CA mutation in colorectal cancer patients. Patients with PIK3CA mutation should be followed up carefully. Moreover, our result suggests that inhibition of PIK3CA mutant may be a new molecular target therapy.

Effect of classification based on combination of mutation and methylation in colorectal cancer prognosis

Colorectal cancer (CRC) is caused by an accumulation of genetic alterations and epigenetic alterations. The molecular classification of CRCs based on genetic alterations and epigenetic alterations is evolving. Here, we examined mutations and methylation status in CRCs to determine if the combination of genetic and epigenetic alterations predicts prognosis. We examined 134 sporadic CRCs. We used the direct sequencing method to identify mutations in BRAF and AKT1, which are downstream of KRAS and PIK3CA, respectively, in the EGFR pathway. We used the Methylight method to determine the methylation status of hMLH1, p16, MINT1, MINT2 and MINT31. Both BRAF and AKT1 mutations were found in only one case (0.75%). Aberrant methylation of hMLH1, p16, MINT1, MINT2 and MINT31 was detected in 22.4, 35.1, 32.8, 59.7 and 41.0% of cases, respectively. The clinicopathological factors were not significantly correlated to mutation or methylation. Among the patients who had no mutation in the EGFR pathway, the overall survival was significantly shorter in the patients with methylation compared to the patients with no methylation in hMLH1 and p16 (p=0.0318). Methylation could play a key role in the prognosis of patients without mutations in the EGFR pathway. The combination of genetic and epigenetic alterations may be a good marker for the prognosis of CRC patients.

Validation and Clinical Use of the Japanese Classification of Colorectal Carcinomatosis: Benefit of Surgical Cytoreduction Even without Hyperthermic Intraperitoneal Chemotherapy

Background: This study aimed to validate an easy to use practical classification of peritoneal metastasis arising from colorectal cancer. Patients and Methods: Data from 2,134 consecutive patients who underwent resection for colorectal cancer at a single institution were reviewed. Peritoneal metastasis was classified depending on extent into three groups (P1–P3). The macroscopic radical resection rates and survival of patients with colorectal cancer complicated with peritoneal metastasis were analyzed. Results: Of the 2,134 patients, 116 (5.4%) had peritoneal metastasis. Among them, 20 (17.2%) underwent macroscopic radical resection. Tumor location on the right side was associated with more extensive peritoneal metastasis (p = 0.010). Male gender (p = 0.0027), liver metastasis (p = 0.0021), and P3 peritoneal metastasis were independent risk factors for noncurative resection. The Cox proportional hazards model showed that gender (p = 0.031), operation period (p = 0.031), and macroscopic radical resection for colorectal cancer and peritoneal metastasis (p = 0.031) were independent prognostic factors. Conclusions: Being female with left colon cancer complicated with P1 or P2 peritoneal metastasis is a good indicator for macroscopic radical resection if liver metastasis is absent. The present classification helped to determine surgical indication for patients with colorectal cancer complicated with synchronous peritoneal metastasis in routine clinical practice.

Clinical Significance of Lymph Node Ratio and Location of Nodal Involvement in Patients with Right Colon Cancer

Background/Aims: Increasing negative lymph node count has been reported to be associated with better outcomes in patients with colon cancer. The present study aimed to clarify the clinical significance of the lymph node ratio (LNR) and location of lymph node metastasis (LNM) in patients with stage III right colon cancer. Methods: We enrolled 820 patients who had undergone curative resection due to colon cancer at a single institution between 1991 and 2005. Among them, 197 underwent curative resection for T2–T4 right colon cancer. We evaluated the oncological outcomes according to LNR (quartiles) and distribution of LNM (n1 = LNM adjacent to the colon or along the vascular arcades of the marginal arteries; n2 = LNM along the major vessels; n3 = LNM near the roots of the major vessels). Results: The rates of LNM in T2, T3 and T4 right colon cancer were 11.1, 38.6 and 58.0%, respectively (p < 0.0001). Recurrence rates were 27.3, 37.5 and 57.1% in patients with n1, n2 and n3 LNM, respectively (p < 0.0001). LNR (p < 0.0001) and distribution of LNM (p = 0.046) were independent risk factors for recurrence in patients with stage III right colon cancer. Conclusions: Some patients with extensive LNM benefited from lymph node dissection with high ligation. Those with T3–T4 right colon cancer are suitable candidates for lymph node dissection with high ligation. Adding the concept of LNR and location of LNM to conventional TNM staging could improve the accuracy of evaluating nodal status.

Clinical significance of UNC5B expression in colorectal cancer

The purpose of this study was to find a methylation-related gene that could become a biomarker or therapeutic target in colorectal carcinoma (CRC). We screened candidate genes suspected to be silenced by DNA methylation using cDNA microarray analysis. To investigate the clinical significance of one candidate gene (UNC5B), we analyzed the correlation between mRNA expression and clinicopathological features using clinical tissue samples. Moreover, methylation specific PCR analysis was performed to reveal whether the promoter region was methylated in CRC cell lines. We found 75 candidate genes that were potentially suppressed by DNA methylation in CRC. We focused on UNC5B, a possible tumor suppressor gene and regulator of apoptosis known to be inactivated in CRC. The mRNA expression analysis using tissue samples revealed that UNC5B mRNA was down-expressed in about 20% of CRC patients, and the patients with low-UNC5B-expression tumors showed a significantly higher recurrence rate after curative surgery. According to the univariate and multivariate analysis, low UNC5B expression was an independent risk factor for postoperative recurrence in stage I, II and III CRC patients. Furthermore, patients with low expression of UNC5B in tumors had significantly poorer prognosis than those with high expression of UNC5B. Although UNC5B mRNA expression was restored by the demethylation treatment in CRC cell lines, the promoter region of UNC5B was not methylated. UNC5B is a potential biomarker for the selection of patients with high risk of postoperative recurrence and worse prognosis in CRC.

JTE‐522, a selective COX‐2 inhibitor, interferes with the growth of lung metastases from colorectal cancer in rats due to inhibition of neovascularization: A vascular cast model study

The lung is a frequent site of metastasis from colorectal cancer, but angiogenesis of lung metastases has not been clarified. Some COX‐2 inhibitors prevent tumor growth, although the inhibitory mechanism at the metastatic site is obscure. We investigated the microvascular structure of small lung metastases and the effect of JTE‐522, a selective COX‐2 inhibitor, on the angiogenesis of pulmonary metastases from colorectal cancer in rats. The tail veins of 25 male F344/DuCrj rats, aged 5 weeks, were injected with a tumor suspension containing 5 × 106 RCN‐9, a rat colon cancer cell line. Three weeks later, pulmonary vascular resin corrosion casts were taken and the vascularity of metastases was studied using stereo and scanning electron microscopes. We investigated the effect of 0, 10 and 30 mg/kg/day of JTE‐522 on the angiogenesis of pulmonary metastases in 3 groups of 5 male rats out of 25. JTE‐522 reduced the diameter of tumor vessels as well as the number and size of metastatic tumors. The diameter of tumor vessels and the size of lung metastases significantly and positively correlated with neovascularization in the control group, but not in the JTE‐522‐treated groups. JTE‐522 also affected type of vasculature of metastases, which differed depending on their size. JTE‐522 interfered with the growth of hematogenous metastatic tumors by disrupting neovascularization. However, JTE‐522 may have some important mechanisms other than inhibition of neovascularization. JTE‐522 may be one of the therapeutic agents for the treatment of hematogenous metastasis of colorectal cancer.

JTE-522, a selective COX-2 inhibitor, inhibits growth of pulmonary metastases of colorectal cancer in rats

BackgroundEpidemiological studies have shown that individuals who regularly consume NSAIDs have lower rates of mortality associated with colorectal cancer. Because COX-2 inhibitors prevent tumor growth through some mechanisms, we assessed the effect of JTE-522, a selective COX-2 inhibitor, on pulmonary metastases of colon cancer in a rat model.MethodsA suspension of 5 × 106 RCN-9 (rat colon cancer cells) was injected into the tail vein of 24 anesthetized male F344/DuCrj rats. Oral JTE-522 (0, 3, 10, or 30 mg/kg/day) was administered from the day before RCN-9 injection until the end of the study. Twenty-four days later, the lungs were removed from sacrificed rats and weighed. Pulmonary metastatic tumors were microscopically evaluated in the largest cross sections. We also performed immunohistochemical staining for both COX-2 and VEGF.ResultsJTE-522 dose-dependently decreased lung weight (p = 0.001) and the size of pulmonary metastatic tumors (p = 0.0002). However, the differences in the number of metastatic tumors among 4 groups were insignificant. Significant adverse effects of JTE-522 were undetectable. Immunohistochemical staining showed high levels of both COX-2 and VEGF in pulmonary metastatic tumors.ConclusionJTE-522 dose-dependently decreased the size, but not the number of pulmonary metastases. COX-2 inhibitors might block metastatic tumor growth, but not actual metastasis. Selective COX-2 inhibitors might be useful as therapeutic agents that inhibit the growth of metastatic tumors, as well as the tumorigenesis of colorectal cancer.

Cyclooxygenase-2 Overexpression Is Related to Polypoid Growth and K-ras Gene Mutation in T1 Colorectal Carcinomas

PURPOSECyclooxygenase-2 is thought to play a role in the development of intestinal tumors and levels are elevated in approximately 80 to 90 percent of human colorectal carcinomas. To clarify the role that cyclooxygenase-2 plays in the development of colorectal carcinoma, we studied the relationship between cyclooxygenase-2 expression and tumor morphology and that between cyclooxygenase-2 expression and K-ras mutation.METHODSWe classified 48 T1 colorectal carcinomas as polypoid or nonpolypoid and analyzed the clinicopathologic features. The expression of cyclooxygenase-2 was determined immunohistochemically, and nested polymerase chain reaction-restriction fragment length polymorphism detected a K-ras codon 12 mutation.RESULTSCyclooxygenase-2 expression was higher in polypoid carcinomas than in nonpolypoid carcinomas (P < 0.001). The K-ras codon 12 mutation was associated with higher levels of cyclooxygenase-2 expression compared with carcinomas without this mutation (P = 0.028).CONCLUSIONSPolypoid growth and K-ras gene mutation are both associated with increased levels of cyclooxygenase-2 expression in T1 tumors.

Laparoscopic-assisted colectomy in a patient with colon cancer after percutaneous endoscopic gastrostomy

BackgroundA number of patients undergo percutaneous endoscopic gastrostomy (PEG) under various conditions. Open colectomy is usually performed for colon cancer in patients with PEG because the safety of the laparoscopic approach for such patients has not been established. However, if the laparoscopic approach is possible in patients with PEG, it will be less invasive and more helpful in rehabilitation into society.Case presentationWe describe the case of a 64-year-old male with a T1 adenocarcinoma of the ascending colon 2 years after surgery for nasal cancer and PEG for dysphagia. The patient did not have any distant metastases or malignant tumors on preoperative computed tomography and positron-emission tomography. He underwent laparoscopic-assisted colectomy (LAC) with lymph node dissection. No complications developed during or after the surgery.ConclusionsLAC could be a potential option for the treatment of colon cancer in patients who have undergone PEG. To our knowledge, this is the first recorded case of an ascending colon cancer treated with LAC under the condition of gastrostoma.