CpG island methylator phenotype identifies high risk patients among microsatellite stable BRAF mutated colorectal cancers.

The prognostic value of CpG island methylator phenotype (CIMP) in colorectal cancer remains unsettled. We aimed to assess the prognostic value of this phenotype analyzing a total of 1126 tumor samples obtained from two Norwegian consecutive colorectal cancer series. CIMP status was determined by analyzing the 5-markers CAGNA1G, IGF2, NEUROG1, RUNX3 and SOCS1 by quantitative methylation specific PCR (qMSP). The effect of CIMP on time to recurrence (TTR) and overall survival (OS) were determined by uni- and multivariate analyses. Subgroup analyses were conducted according to MSI and BRAF mutation status, disease stage, and also age at time of diagnosis (<60, 60-74, ≥75 years). Patients with CIMP positive tumors demonstrated significantly shorter TTR and worse OS compared to those with CIMP negative tumors (multivariate hazard ratio [95% CI] 1.86 [1.31-2.63] and 1.89 [1.34-2.65], respectively). In stratified analyses, CIMP tumors showed significantly worse outcome among patients with microsatellite stable (MSS, P < 0.001), and MSS BRAF mutated tumors (P < 0.001), a finding that persisted in patients with stage II, III or IV disease, and that remained significant in multivariate analysis (P < 0.01). Consistent results were found for all three age groups. To conclude, CIMP is significantly associated with inferior outcome for colorectal cancer patients, and can stratify the poor prognostic patients with MSS BRAF mutated tumors.

Multiregional transcriptomics identifies congruent consensus subtypes with prognostic value beyond tumor heterogeneity of colorectal cancer.

Intra-tumor heterogeneity compromises the clinical value of transcriptomic classifications of colorectal cancer. We investigated the prognostic effect of transcriptomic heterogeneity and the potential for classifications less vulnerable to heterogeneity in a single-hospital series of 1093 tumor samples from 692 patients, including multiregional samples from 98 primary tumors and 35 primary-metastasis sets. We show that intra-tumor heterogeneity of the consensus molecular subtypes (CMS) is frequent and has poor-prognostic associations independently of tumor microenvironment markers. Multiregional transcriptomics uncover cancer cell-intrinsic and low-heterogeneity signals that recapitulate the intrinsic CMSs proposed by single-cell sequencing. Further subclassification identifies congruent CMSs that explain a larger proportion of variation in patient survival than intra-tumor heterogeneity. Plasticity is indicated by discordant intrinsic phenotypes of matched primary and metastatic tumors. We conclude that multiregional sampling reconciles the prognostic power of tumor classifications from single-cell and bulk transcriptomics in the context of intra-tumor heterogeneity, and phenotypic plasticity challenges the reconciliation of primary and metastatic subtypes.

Prognostic impact of lymph node harvest and lymph node ratio in patients with colon cancer.

BACKGROUND: The prognostic impact of the number of lymph nodes and ratio in colon cancer is still debated. OBJECTIVES: The aim of this study was to evaluate lymph node harvest in patients with colon cancer over time, and to test the hypotheses that investigation of more lymph nodes, and low lymph node ratio in stage III patients, has positive prognostic impact. DESIGN: This is a prospective, observational study. SETTINGS: This study was conducted in a single institution treating all patients with colon cancer in a defined catchment area. PATIENTS: All patients admitted in the period 1993 to 2009 (n = 1481) were included. MAIN OUTCOME MEASURES: The primary outcomes measured were the number of examined regional lymph nodes according to treatment period, 5-year overall survival and time to recurrence, and univariate (Kaplan-Meier) and multivariate (Cox regression) analyses of prognostic factors. RESULTS: Nine hundred fifty (65%) patients underwent curative resection. Median number of examined lymph nodes increased from 7 to 15 (p < 0.001), and the proportion of patients with stage III disease increased from 25% to 33% (p = 0.02) during the study period. In patients with stage I to III disease, time to recurrence (proportion of patients without recurrence or death of colon cancer) improved from 65% to 82% during the period (p < 0.001). An association between lymph node count (<8 compared with ≥ 12) and overall survival was found for patients with stage II disease (57% vs 71%, p = 0.004). Hazard ratio for death within 5 years was 0.7 (p = 0.043) when 8 to 11 nodes were examined and 0.6 (p = 0.001) when ≥ 12 nodes were examined (<8 reference). In patients with stage III disease, increasing lymph node ratio was associated with reduced overall survival and time to recurrence in uni- and multivariate analyses. LIMITATIONS: This study was limited by the small number of patients in each stage. CONCLUSIONS: The number of examined lymph nodes increased in the study period. A stage migration was observed, and time to recurrence improved in patients with stage I to III disease. In patients with stage III disease, lymph node ratio was a stronger prognostic factor than the total number of lymph nodes examined.

Lymph node micrometastases and isolated tumor cells influence survival in stage I and II colon cancer.

PURPOSE: Lymph-node status is considered the most important prognostic factor in colorectal cancer. The aim of the present prospective study was to evaluate the influence of micrometastases and isolated tumor cells on recurrence and disease-free survival in colon cancer. METHODS: A total of 193 patients with colon cancer, operated on between 2000 and 2005, were enrolled in the study. All lymph nodes were examined by routine microscopy in hematoxylin and eosin-stained sections. If no metastases were identified in any node, all nodes were examined immunohistochemically with monoclonal antibody CAM 5.2. RESULTS: Ordinary metastases were found in 67 patients, leaving 126 patients in stage I/II. Immunohistochemistry showed that 5% (6/126) of these had micrometastases and 26% (33/126) had isolated tumor cells. A median of 5 years of follow-up revealed local or distant recurrence in 23% (9/39) of stage I/II patients with micrometastases or isolated tumor cells, compared with 7% (6/87) without micrometastases or isolated tumor cells (P = .010). Five-year disease-free survival for patients with and without micrometastases or isolated tumor cells was 75% and 93%, respectively (P = .012). When analyzed separately, patients with isolated tumor cells (excluding micrometastases) had also lower survival than node-negative patients (P = .012). CONCLUSION: The presence of micrometastases and isolated tumor cells was found to be a prognostic factor for recurrence and disease-free survival. This may have implications for future treatment of stage I/II colon cancer.

Sentinel node mapping does not improve staging of lymph node metastasis in colonic cancer.

PURPOSE: This study was designed to evaluate the reliability of the sentinel node concept in colonic cancer. METHODS: Patent blue was used as tracer. The four blue nodes closest to the tumor were defined as the sentinel node(s) by the pathologist. All nodes were examined by routine microscopy (hematoxylin-eosin staining). If no metastases were detected, all lymph nodes were examined immunohistochemically with antibody to cytokeratin. RESULTS: Two hundred colon specimens were examined. Sentinel node(s) were identified in 93 percent. Sixty contained metastases in hematoxylin-eosin sections. In 32 these were found in sentinel nodes (sensitivity 53 percent). Twenty-eight patients had metastases in nonsentinel nodes only, giving a false-negative rate of 47 percent. Immunostaining revealed 39 (30 percent) micrometastases or submicrometastases in 131 TNM Stages I and II patients, and in 17 of these patients metastases were found in nonsentinel nodes only (false-negative rate 44 percent). CONCLUSIONS: Sentinel lymph node mapping shows low sensitivity for detection of ordinary metastases, micrometastases, and submicrometastases. If only the sentinel nodes had been examined, approximately half of the metastases would have been lost after routine staining, as well as half of the micrometastases and submicrometastases when immunohistochemical examination was added.

DNA sequence profiles of the colorectal cancer critical gene set KRAS-BRAF-PIK3CA-PTEN-TP53 related to age at disease onset.

The incidence of colorectal cancer (CRC) increases with age and early onset indicates an increased likelihood for genetic predisposition for this disease. The somatic genetics of tumor development in relation to patient age remains mostly unknown. We have examined the mutation status of five known cancer critical genes in relation to age at diagnosis, and compared the genomic complexity of tumors from young patients without known CRC syndromes with those from elderly patients. Among 181 CRC patients, stratified by microsatellite instability status, DNA sequence changes were identified in KRAS (32%), BRAF (16%), PIK3CA (4%), PTEN (14%) and TP53 (51%). In patients younger than 50 years (n = 45), PIK3CA mutations were not observed and TP53 mutations were more frequent than in the older age groups. The total gene mutation index was lowest in tumors from the youngest patients. In contrast, the genome complexity, assessed as copy number aberrations, was highest in tumors from the youngest patients. A comparable number of tumors from young (<50 years) and old patients (>70 years) was quadruple negative for the four predictive gene markers (KRAS-BRAF-PIK3CA-PTEN); however, 16% of young versus only 1% of the old patients had tumor mutations in PTEN/PIK3CA exclusively. This implies that mutation testing for prediction of EGFR treatment response may be restricted to KRAS and BRAF in elderly (>70 years) patients. Distinct genetic differences found in tumors from young and elderly patients, whom are comparable for known clinical and pathological variables, indicate that young patients have a different genetic risk profile for CRC development than older patients.