Context-dependent interpretation of the prognostic value of BRAF and KRAS mutations in colorectal cancer.

BACKGROUND: The mutation status of the BRAF and KRAS genes has been proposed as prognostic biomarker in colorectal cancer. Of them, only the BRAF V600E mutation has been validated independently as prognostic for overall survival and survival after relapse, while the prognostic value of KRAS mutation is still unclear. We investigated the prognostic value of BRAF and KRAS mutations in various contexts defined by stratifications of the patient population. METHODS: We retrospectively analyzed a cohort of patients with stage II and III colorectal cancer from the PETACC-3 clinical trial (N = 1,423), by assessing the prognostic value of the BRAF and KRAS mutations in subpopulations defined by all possible combinations of the following clinico-pathological variables: T stage, N stage, tumor site, tumor grade and microsatellite instability status. In each such subpopulation, the prognostic value was assessed by log rank test for three endpoints: overall survival, relapse-free survival, and survival after relapse. The significance level was set to 0.01 for Bonferroni-adjusted p-values, and a second threshold for a trend towards statistical significance was set at 0.05 for unadjusted p-values. The significance of the interactions was tested by Wald test, with significance level of 0.05. RESULTS: In stage II-III colorectal cancer, BRAF mutation was confirmed a marker of poor survival only in subpopulations involving microsatellite stable and left-sided tumors, with higher effects than in the whole population. There was no evidence for prognostic value in microsatellite instable or right-sided tumor groups. We found that BRAF was also prognostic for relapse-free survival in some subpopulations. We found no evidence that KRAS mutations had prognostic value, although a trend was observed in some stratifications. We also show evidence of heterogeneity in survival of patients with BRAF V600E mutation. CONCLUSIONS: The BRAF mutation represents an additional risk factor only in some subpopulations of colorectal cancers, in others having limited prognostic value. However, in the subpopulations where it is prognostic, it represents a marker of much higher risk than previously considered. KRAS mutation status does not seem to represent a strong prognostic variable.

Identification of MAGI1 as a tumor-suppressor protein induced by cyclooxygenase-2 inhibitors in colorectal cancer cells.

Cyclooxyganase-2 (COX-2), a rate-limiting enzyme in the prostaglandin synthesis pathway, is overexpressed in many cancers and contributes to cancer progression through tumor cell-autonomous and paracrine effects. Regular use of non-steroidal anti-inflammatory drugs or selective COX-2 inhibitors (COXIBs) reduces the risk of cancer development and progression, in particular of the colon. The COXIB celecoxib is approved for adjunct therapy in patients with Familial adenomatous polyposis at high risk for colorectal cancer (CRC) formation. Long-term use of COXIBs, however, is associated with potentially severe cardiovascular complications, which hampers their broader use as preventive anticancer agents. In an effort to better understand the tumor-suppressive mechanisms of COXIBs, we identified MAGUK with Inverted domain structure-1 (MAGI1), a scaffolding protein implicated in the stabilization of adherens junctions, as a gene upregulated by COXIB in CRC cells and acting as tumor suppressor. Overexpression of MAGI1 in CRC cell lines SW480 and HCT116 induced an epithelial-like morphology; stabilized E-cadherin and β-catenin localization at cell-cell junctions; enhanced actin stress fiber and focal adhesion formation; increased cell adhesion to matrix proteins and suppressed Wnt signaling, anchorage-independent growth, migration and invasion in vitro. Conversely, MAGI1 silencing decreased E-cadherin and β-catenin localization at cell-cell junctions; disrupted actin stress fiber and focal adhesion formation; and enhanced Wnt signaling, anchorage-independent growth, migration and invasion in vitro. MAGI1 overexpression suppressed SW480 and HCT116 subcutaneous primary tumor growth, attenuated primary tumor growth and spontaneous lung metastasis in an orthotopic model of CRC, and decreased the number and size of metastatic nodules in an experimental model of lung metastasis. Collectively, these results identify MAG1 as a COXIB-induced inhibitor of the Wnt/β-catenin signaling pathway, with tumor-suppressive and anti-metastatic activity in experimental colon cancer.

The type of K-ras mutation determines prognosis in colorectal cancer.

BACKGROUND: Mutations involving the oncogene K-ras in colorectal cancer may be related to tumor aggressiveness. However, the value of K-ras gene determination as a prognostic marker has not been clearly established. PATIENTS AND METHODS: The results from 98 patients recruited in a prospective study analyzing the effect of a K-ras mutation as a prognostic factor in colorectal cancer are reported. RESULTS: Disease-free (P = 0.02) and overall survival (P = 0.03) were significantly reduced for patients harboring a K-ras mutation. Two specific mutations demonstrated a significantly increased risk of disease recurrence, namely, 12-TGT (P = 0.04) and 13-GAC substitutions (P = 0.002). Patients with either of these substitutions had a 2-year disease-free survival rate of 37% compared with that of 67% for the group of patients harboring any other mutation type or a wild-type status (P = 0.01). CONCLUSIONS: The results herein presented suggest that K-ras acts as a prognostic factor in colorectal cancer and that this effect is probably related to a limited number of defined mutations.

A comprehensive characterization of genome-wide copy number aberrations in colorectal cancer reveals novel oncogenes and patterns of alterations.

To develop a comprehensive overview of copy number aberrations (CNAs) in stage-II/III colorectal cancer (CRC), we characterized 302 tumors from the PETACC-3 clinical trial. Microsatellite-stable (MSS) samples (n = 269) had 66 minimal common CNA regions, with frequent gains on 20 q (72.5%), 7 (41.8%), 8 q (33.1%) and 13 q (51.0%) and losses on 18 (58.6%), 4 q (26%) and 21 q (21.6%). MSS tumors have significantly more CNAs than microsatellite-instable (MSI) tumors: within the MSI tumors a novel deletion of the tumor suppressor WWOX at 16 q23.1 was identified (p<0.01). Focal aberrations identified by the GISTIC method confirmed amplifications of oncogenes including EGFR, ERBB2, CCND1, MET, and MYC, and deletions of tumor suppressors including TP53, APC, and SMAD4, and gene expression was highly concordant with copy number aberration for these genes. Novel amplicons included putative oncogenes such as WNK1 and HNF4A, which also showed high concordance between copy number and expression. Survival analysis associated a specific patient segment featured by chromosome 20 q gains to an improved overall survival, which might be due to higher expression of genes such as EEF1B2 and PTK6. The CNA clustering also grouped tumors characterized by a poor prognosis BRAF-mutant-like signature derived from mRNA data from this cohort. We further revealed non-random correlation between CNAs among unlinked loci, including positive correlation between 20 q gain and 8 q gain, and 20 q gain and chromosome 18 loss, consistent with co-selection of these CNAs. These results reinforce the non-random nature of somatic CNAs in stage-II/III CRC and highlight loci and genes that may play an important role in driving the development and outcome of this disease.

Systematic review and meta-analysis of risk factors for survival after lung metastasectomy in colorectal cancer patients

Objective: Resection of lung metastases (LM) from colorectal cancer (CRC)¦is increasingly performed with a curative intent.Most series report small groups¦of patients, and it is currently not possible to identify those CRC patients who¦may benefit the most of surgical management. It is clinically relevant to assess¦risk factors for prolonged survival after this type of procedures.¦Methods: A meta analysis of 24 series published between 2000 and 2011¦which focused on surgical management of LM from CRC and included more¦than 40 patients each, with or without prior resection of in transit liver¦metastases. Random effects were calculated for five variables considered as¦potential prognostic factors.¦Results: A total of 2815 patients who underwent surgery with a curative¦intent were considered in this analysis. Four parameters were associated with¦a decreased survival: 1) a short disease-free interval between primary tumor¦resection and development of LM (HR = 1·59, 95% CI 1·27-1·98); 2) multiple¦LM (HR = 2·04, 95%CI 1·72-2·41); 3) positive hilar/mediastinal lymph nodes¦(HR = 1·65, 95% CI 1·35-2·02); and 4) a high prethoracotomy CEA value (HR¦=1·91, 95% CI 1·57-2·32). By comparison, a history of resected liver metastases¦(HR = 1·36, 95% CI 0·92-2·03) did not achieve statistical significance.¦Conclusion: Risk factors for poor clinical outcome after surgery for lung¦metastases in CRC patients include: 1) synchronous lung metastases; 2) high¦pre-thoracotomy CEA; 3) hilar nodes involvement; and 4) multiple pulmonary¦lesions.

Immune Microenvironment in Colorectal Cancer: A New Hallmark to Change Old Paradigms

Impact of immune microenvironment in prognosis of solid tumors has been extensively studied in the last few years. Specifically in colorectal carcinoma, increased knowledge of the immune events around these tumors and their relation with clinical outcomes have led to consider immune microenvironment as one of the most important prognostic factors in this disease. In this review we will summarize and update the current knowledge with respect to this intriguing and complex new hallmark of cancer, paying special attention to infiltration by T-infiltrating lymphocytes and their subtypes in colorectal cancer, as well as its eventual clinical translation in terms of long-term prognosis. Finally, we suggest some possible investigational approaches based on combinatorial strategies to trigger and boost immune reaction against tumor cells.

Genetic analysis of caveolin-1 and eNOS genes in colorectal cancer.

Caveolae are involved in physical compartmentalization between different groups of signaling events. Its main component, CAV1, modulates different pathways in cellular physiology. The emerging evidence pointing to the role of CAV1 in cancer led us to study whether different alleles of this gene are associated with colorectal cancer (CRC). Since one of the most characterized enzymes regulated by CAV1 is eNOS, we decided to include both genes in this study. We analyzed five SNPs in 360 unrelated CRC patients and 550 controls from the general population. Two of these SNPs were located within eNOS and three within the CAV1 gene. Although haplotype distribution was not associated with CRC, haplotype TiA (CAV1) was associated with familiar forms of CRC (p<0.05). This was especially evident in CRC antecedents and nuclear forms of CRC. If both CG (eNOS) and TiA (CAV1) haplotypes were taken together, this association increased in significance. Thus, we propose that CAV1, either alone or together with eNOS alleles, might modify CRC heritability.

Analysis of CXCL12 3 ' UTR G > A polymorphism in colorectal cancer

Colorectal cancer is one of the most prevalent cancers in developed countries. However, the genetic factors influencing its appearance remain far from being fully characterized. Recently, a G>A functional transition mapping the 3' untranslated region of the CXCL12 gene (rs1801157) has been found to be under-represented among rectal cancer patients when compared to colon cancer patients from a Swedish series. Here we present the results from an independent analysis of CXCL12 rs1801157 in a larger CRC series of Spanish origin in order to analyse the robustness of this association within a different European population. No significant difference was observed between controls and colon or rectal cancer patients. We were also unable to find a correlation between rs1801157 and different prognostic markers such as metastasis development or disease-free survival time. The epidemiologic data involving CXCL12 rs1801157 in colorectal cancer risk are discussed.

Perioperative anemia management in colorectal cancer patients: A pragmatic approach.

Anemia, usually due to iron deficiency, is highly prevalent among patients with colorectal cancer. Inflammatory cytokines lead to iron restricted erythropoiesis further decreasing iron availability and impairing iron utilization. Preoperative anemia predicts for decreased survival. Allogeneic blood transfusion is widely used to correct anemia and is associated with poorer surgical outcomes, increased post-operative nosocomial infections, longer hospital stays, increased rates of cancer recurrence and perioperative venous thromboembolism. Infections are more likely to occur in those with low preoperative serum ferritin level compared to those with normal levels. A multidisciplinary, multimodal, individualized strategy, collectively termed Patient Blood Management, minimizes or eliminates allogeneic blood transfusion. This includes restrictive transfusion policy, thromboprophylaxis and anemia management to improve outcomes. Normalization of preoperative hemoglobin levels is a World Health Organization recommendation. Iron repletion should be routinely ordered when indicated. Oral iron is poorly tolerated with low adherence based on published evidence. Intravenous iron is safe and effective but is frequently avoided due to misinformation and misinterpretation concerning the incidence and clinical nature of minor infusion reactions. Serious adverse events with intravenous iron are extremely rare. Newer formulations allow complete replacement dosing in 15-60 min markedly facilitating care. Erythropoiesis stimulating agents may improve response rates. A multidisciplinary, multimodal, individualized strategy, collectively termed Patient Blood Management used to minimize or eliminate allogeneic blood transfusion is indicated to improve outcomes.

Risk factors for survival after lung metastasectomy in colorectal cancer patients: systematic review and meta-analysis.

ABSTRACT  Despite the lack of randomized trials, lung metastasectomy is currently proposed for colorectal cancer patients under certain conditions. Many retrospective studies have reported different prognostic factors of poorer survival, but eligibility for pulmonary metastasectomy remains determined by the complete resection of all pulmonary metastases. The aim of this review is to clarify which pre-operative risk factors reported in systematic reviews or meta-analysis are determinant for survival in colorectal metastatic patients. Different criteria have been now identified to select which patient will really benefit from lung metastasectomy.

Survival after lung metastasectomy in colorectal cancer patients with previously resected liver metastases.

BACKGROUND: Resection of hepatic metastases is indicated in selected stage IV colorectal cancer (CRC) patients. A minority will eventually develop pulmonary metastases and may undergo lung surgery with curative intent. The aims of the present study were to assess clinical outcome and identify parameters predicting survival after pulmonary metastasectomy in patients who underwent prior resection of hepatic CRC metastases.¦METHODS: We performed a retrospective analysis of 27 consecutive patients (median age 62 years; range: 33-75 years) who underwent resection of pulmonary metastases after previous hepatic metastasectomy from CRC in two institutions from 1996 to 2009. All patients underwent complete resection (R0) for both colorectal and hepatic metastases.¦RESULTS: Median follow-up was 32 months (range: 3-69 months) after resection of lung metastases and 65 months (range: 19-146 months) after resection of primary CRC. Three- and 5-year overall survival rates after lung surgery were 56 and 39%, respectively, and median survival was 46 months (95% CI 35-57). Median disease-free survival after pulmonary metastasectomy was 13 months (95% CI 5-21). At the time of last follow-up, seven patients (26%) had no evidence of recurrent disease and 6 of these 7 patients presented initially with a single lung metastasis.¦CONCLUSIONS: Resection of lung metastases from CRC patients may result in prolonged survival, even after previous hepatic metastasectomy. Yet, prolonged disease-free survival remains the exception, and seems to occur only in patients with a single lung lesion.

Risk factors for survival after lung metastasectomy in colorectal cancer patients: a systematic review and meta-analysis.

BACKGROUND: Resection of lung metastases (LM) from colorectal cancer (CRC) is increasingly performed with a curative intent. It is currently not possible to identify those CRC patients who may benefit the most from this surgical strategy. The aim of this study was to perform a systematic review of risk factors for survival after lung metastasectomy for CRC. METHODS: We performed a meta-analysis of series published between 2000 and 2011, which focused on surgical management of LM from CRC and included more than 40 patients each. Pooled hazard ratios (HR) were calculated by using random effects model for parameters considered as potential prognostic factors. RESULTS: Twenty-five studies including a total of 2925 patients were considered in this analysis. Four parameters were associated with poor survival: (1) a short disease-free interval between primary tumor resection and development of LM (HR 1.59, 95 % confidence interval [CI] 1.27-1.98); (2) multiple LM (HR 2.04, 95 % CI 1.72-2.41); (3) positive hilar and/or mediastinal lymph nodes (HR 1.65, 95 % CI 1.35-2.02); and (4) elevated prethoracotomy carcinoembryonic antigen (HR 1.91, 95 % CI 1.57-2.32). By comparison, a history of resected liver metastases (HR 1.22, 95 % CI 0.91-1.64) did not achieve statistical significance. CONCLUSIONS: Clinical variables associated with prolonged survival after surgery for LM in CRC patients include prolonged disease-free interval between primary tumor and metastatic spread, normal prethoracotomy carcinoembryonic antigen, absence of thoracic node involvement, and a single pulmonary lesion.

Nodal staging in colorectal cancer: should distant lymph nodes be recovered in surgical specimens?

To assess the value of sampling lymph nodes located far sidelong colorectal cancer specimens, we analyzed retrospectively surgical specimens from 345 colorectal cancer patients. The mesocolic and perirectal fat was divided into 2 fractions: close to (<5 cm) and distant from (>5 cm) the tumor. Tumors were located in the cecum (n = 61), ascending colon (n = 29), transverse colon (n = 31), descending colon (n = 27), sigmoid colon (n = 108), and rectum (n = 89). The median number of lymph nodes sampled was 17 in both fractions (range, 4-66), 12 (range, 0-46) in the close fraction, and 3 (range, 0-33) in the distant fraction. There were 169 pN0, 104 pN1, and 72 pN2 cases. The pN staging was accurate in all cases except 10 based on the close fraction alone; of these, 6 were upstaged from pN0 to pN1 and 4 from pN1 to pN2 when the distant fraction was considered. Among pN1-upstaged cases, 5 were rectal (3/5 with neoadjuvant radiotherapy) and 1 colonic. In the colon, we found that lymph node location is more important than lymph node number because metastatic lymph nodes were present mostly in the peritumoral area. This suggests that lymph nodes should be initially recovered from the pericolic fat close to the tumor. If there are less than 4 positive lymph nodes and less than 12 lymph nodes examined in total, additional lymph nodes should be retrieved from the distal fraction for potential upstaging. In the rectum, systematic sampling of close and distant lymph nodes is mandatory because in rare cases, metastases are detected only in distant lymph nodes, particularly in patients who have undergone neoadjuvant radiotherapy.

Identification by Real-time PCR of 13 mature microRNAs differentially expressed in colorectal cancer and non-tumoral tissues

MicroRNAs (miRNAs) are short non-coding RNA molecules playing regulatory roles by repressing translation or cleaving RNA transcripts. Although the number of verified human miRNA is still expanding, only few have been functionally described. However, emerging evidences suggest the potential involvement of altered regulation of miRNA in pathogenesis of cancers and these genes are thought to function as both tumours suppressor and oncogenes. In our study, we examined by Real-Time PCR the expression of 156 mature miRNA in colorectal cancer. The analysis by several bioinformatics algorithms of colorectal tumours and adjacent non-neoplastic tissues from patients and colorectal cancer cell lines allowed identifying a group of 13 miRNA whose expression is significantly altered in this tumor. The most significantly deregulated miRNA being miR-31, miR-96, miR-133b, miR-135b, miR-145, and miR-183. In addition, the expression level of miR-31 was correlated with the stage of CRC tumor. Our results suggest that miRNA expression profile could have relevance to the biological and clinical behavior of colorectal neoplasia.

Recent trends in colorectal cancer mortality in Europe.

Colorectal cancer mortality has been declining over the last two decades in Europe, particularly in women, the trends being, however, different across countries and age groups. We updated to 2007 colorectal cancer mortality trends in Europe using data from the World Health Organization (WHO). Rates were analyzed for the overall population and separately in young, middle-age and elderly populations. In the European Union (EU), between 1997 and 2007 mortality from colorectal cancer declined by around 2% per year, from 19.7 to 17.4/100,000 men (world standardized rates) and from 12.5 to 10.5/100,000 women. Persisting favorable trends were observed in countries of western and northern Europe, while there were more recent declines in several countries of eastern Europe, including the Czech Republic, Hungary and Slovakia particularly in women (but not Romania and the Russian Federation). In 2007, a substantial excess in colorectal cancer mortality was still observed in Slovakia, Hungary, Croatia, the Czech Republic and Slovenia in men (rates over 25/100,000), and in Hungary, Norway, Denmark and Slovakia in women (rates over 14/100,000). Colorectal mortality trends were more favorable in the young (30-49 years) from most European countries, with a decline of ∼2% per year since the early 1990s in both men and women from the EU. The recent decreases in colorectal mortality rates in several European countries are likely due to improvements in (early) diagnosis and treatment, with a consequent higher survival from the disease. Interventions to further reduce colorectal cancer burden are, however, still warranted, particularly in eastern European countries.