Colon cancer prognosis prediction by gene expression profiling

This study assessed the possibility to build a prognosis predictor, based on microarray gene expression measures, in stage II and III colon cancer patients. Tumour (T) and non-neoplastic mucosa (NM) mRNA samples from 18 patients (nine with a recurrence, nine with no recurrence) were profiled using the Affymetrix HGU133A GeneChip. The k-nearest neighbour method was used for prognosis prediction using T and NM gene expression measures. Six-fold cross-validation was applied to select the number of neighbours and the number of informative genes to include in the predictors. Based on this information, one T-based and one NM-based predictor were proposed and their accuracies were estimated by double cross-validation. In six-fold cross-validation, the lowest numbers of informative genes giving the lowest numbers of false predictions (two out of 18) were 30 and 70 with the T and NM gene expression measures, respectively. A 30-gene T-based predictor and a 70-gene NM-based predictor were then built, with estimated accuracies of 78 and 83%, respectively. This study suggests that one can build an accurate prognosis predictor for stage II and III colon cancer patients, based on gene expression measures, and one can use either tumour or non-neoplastic mucosa for this purpose.     

Adjuvant chemotherapy for stage II colon cancer

The use of adjuvant chemotherapy following resection for all patients with stage III colon cancer is now part of the standard of care around the world. Recent trials have led to changes in the standard regimens, which now include the use of oxaliplatin (Eloxatin) for most patients with stage III colon cancer. The addition of oxaliplatin has resulted in a 23% reduction in the risk of recurrence compared with fluorouracil/leucovorin alone, with a small but statistically significant survival benefit. Unfortunately, no adequately powered trial has determined whether adjuvant chemotherapy is beneficial for stage II patients, and its use is much more controversial. Most investigators agree that adjuvant chemotherapy has some activity against stage II disease. However, its impact on progression-free and overall survival remains highly controversial. Despite the lack of data, there is growing acceptance of an informal classification system, which stratifies stage II patients by risk on the basis of clinical data, as a guide for deciding whether to use adjuvant therapy. The only phase III clinical trial for stage II patients currently ongoing in the United States uses molecular classification as the basis for patient randomization.     

Loss of Bcl-2 expression in colon cancer: A prognostic factor for recurrence in stage II colon cancer

AimsTo evaluate the prognostic value of immunohistochemical expression of Bcl-2 in colon cancers.Patients and methodsTwo hundred and twenty-six resected and paraffin-embedded colon carcinomas were analysed by immunostaining using monoclonal antibodies for Bcl-2. We evaluated whether the Bcl-2 staining patterns, semi-quantitatively assessed, could be correlated with the pTNM stage, size and tumour circumference, differentiation, appearance, vascular invasion, perineural invasion, colloid component, margins, involvement of adjacent structures, stromal appearance, flow cytometry and the S-phase.ResultsEighty patients (36%) were considered Bcl-2 positive. The extent of Bcl-2 expression by tumour cells decreased significantly with respect to increasing tumour size (P = 0.042), the extension of parietal invasion pT (P = 0.007), the invasive nature of the tumour (P = 0.024), and extent of the circumference (P = 0.024). In a multivariate analysis, Bcl-2 expression does not appear as an independent prognosis factor in the overall population as in the 166 patients with optimal resection. Of the 59 stage II patients, using univariate analysis, Bcl-2 appears to be predictive of relapse-free survival (P = 0.025) but not of overall survival (P = 0.09).ConclusionThe loss of Bcl-2 expression appears to be correlated with increase in number of relapses in the stage II colon cancers and could be a potential useful additional histo-prognostic marker in therapy decision making. Bcl-2 immunodetection seems to be associated with slower local tumour growth.     

Challenges in the management of stage II colon cancer

Approximately one third of patients diagnosed with early-stage colon cancer will present with lymph node involvement (stage III) and about one quarter with transmural bowel wall invasion but negative lymph nodes (stage II). Adjuvant chemotherapy targets micrometastatic disease to improve disease-free (DFS) and overall survival (OS). While beneficial for stage III patients, the role of adjuvant chemotherapy is unestablished in stage II disease. This likely relates to the improved outcome of these patients, and the difficulties in developing studies with sufficient power to document benefit in this patient population. However, recent investigation also suggests that molecular differences may exist between stage II and III cancers and within stage II patients. Validated pathologic prognostic markers are useful at identifying stage II patients at high risk for recurrence for whom the benefit from adjuvant chemotherapy may be greater. Such high-risk features include higher T stage (T4 v T3), suboptimal lymph node retrieval, presence of lymphovascular invasion, bowel obstruction, or bowel perforation, and poorly differentiated histology. However, for the majority of patients who do not carry any of these adverse features and are classified as "average-risk" stage II patients, the benefit of adjuvant chemotherapy remains unproven. Emerging understanding of the underlying biology of stage II colon cancer has identified molecular markers that may change this paradigm and improve our risk assessment and treatment choices for stage II disease. Assessment of microsatellite stability (MSI), which serves as a marker for DNA mismatch repair (MMR) system function, has emerged as a useful tool for risk stratification of patients with stage II colon cancer. Patients with high frequency of MSI have been shown to have increased OS and limited benefit from 5-fluorouracil (5-FU)-based chemotherapy. Additional research is necessary to clearly define the most appropriate way to use this marker and others in routine clinical practice.     

Cost effectiveness of gene expression profiling for early stage breast cancer: A decision-analytic model

BACKGROUND:

Gene expression profiling (GEP) is being used increasingly for risk stratification to identify women with lymph node‐negative, estrogen receptor‐positive, early stage breast cancer who are most likely to benefit from adjuvant chemotherapy. The authors of this report evaluated the cost effectiveness of recurrence score‐guided treatment using 2 commercially available GEP tests, Oncotype DX (Genomic Health, Redwood City, Calif) and MammaPrint (Agendia Inc., Irvine, Calif), from a third‐party payer's perspective.

METHODS:

A 10‐year Markov model was developed to compare the costs and quality‐adjusted life‐years (QALYs) of treatment decisions guided by either Oncotype DX or MammaPrint in a hypothetical cohort of women with early stage, lymph node‐negative, estrogen receptor‐positive breast cancer who may experience recurrence. Outcomes included no recurrence, recurrence, and death. The costs considered included gene test costs, the costs of adjuvant chemotherapy and other chemotherapy (including premedication, oncology visits, and monitoring for adverse events), the cost of treating recurrence, costs associated with the treatment of adverse events, and end‐of‐life care costs.

RESULTS:

The model demonstrated that the patients who received the Oncotype DX test to guide treatment spent $27,882 (in US dollars) and gained 7.364 QALYs, whereas patients who received the MammaPrint test to guide treatment spent $21,598 and gained 7.461 QALYs. Sensitivity analyses demonstrated that the results were robust to changes in all parameters.

CONCLUSIONS:

The model suggested that MammaPrint is a more cost‐effective GEP test compared with Oncotype DX at a threshold willingness‐to‐pay of $50,000 per QALY. Because Oncotype DX is the most frequently used GEP in clinical practice in the United States, the authors concluded that the current findings have implications for health policy, particularly health insurance reimbursement decisions. Cancer 2012. © 2012 American Cancer Society.     

Tumor microRNA-29a expression and the risk of recurrence in stage II colon cancer

There is emerging evidence for the prognostic role of various microRNA (miRNA) molecules in colon cancer. The aim of this study was therefore to compare the miRNA profiles in the primary tumor of patients with recurrent and non-recurrent colon cancer. The study population included 110 patients, 51 (46%) with stage I and 59 (54%) with stage II disease, who underwent curative colectomies between 1995 and 2005 without adjuvant therapy and for whom reliable miRNA expression data were available. RNA was extracted from formalin-fixed paraffin-embedded (FFPE) tumor samples. Initial profiling, using microarrays, was done in order to identify potential biomarkers of recurrence. The miRNA expression was later verified by quantitative real-time polymerase chain reaction (qRT-PCR). Findings were compared between patients who had a recurrence within 36 months of surgery (bad prognosis group, n=23, 21%) and those who did not (good prognosis group, n=87, 79%) in the entire group and within each stage. The results showed that in stage I, none of the 903 miRNAs tested showed differential expression between patients with good prognosis compared with those with poor prognosis. In contrast, in stage II, one miRNA, miR-29a, showed a clear differential expression between the groups (p=0.028). High expression of miR-29a was associated with a longer disease-free survival (DFS), on both univariate and multivariate analyses. Using miR-29a, the positive predictive value for non-recurrence was 94% (2 recurrences among 31 patients). The differential expression of miR-29a was verified by qRT-PCR, showing a similar impact of this miR on DFS. In conclusion, this study demonstrated a significant impact of miR-29a on the risk of recurrence in patients with stage II but not in patients with stage I colon cancer. Based on these results, a validation study is planned.     

Prognosis of node-positive colon cancer

The most recent American Joint Committee on Cancer/International Union Against Cancer (AJCC/UICC) staging system subgroups patients into one to three and four or more positive nodes. However, the Gastrointestinal Study Group and the National Surgical Adjuvant Breast and Bowel Project divides node-positive patients into one to four and five or greater. A Cox multi-variate retrospective analysis was done of the overall survival of node-positive colon cancer patients with the specific objective of determining the most appropriate subcategorization. Data on 306 patients with node-positive colon cancer who underwent potentially curative surgery from 1970 to 1984 were analyzed retrospectively. No patient received adjuvant chemotherapy. Also excluded were patients with synchronous resected metastatic disease or those with rectal primaries. The median follow-up was 6 years, and the median survival for the entire group was 8.6 years. By univariate analysis, the following were significant prognostic features: number of positive nodes (P less than 0.0001), degree of differentiation (P less than 0.0001), colon primary site (P = 0.009), tumor stage (P = 0.001), and tumor size (P less than 0.0001). Lymphatic/blood vessel invasion and a mucinous histology were not significant. By Cox multivariate analysis the number of positive lymph nodes remained the best discriminant of survival (P = 0.0001). The number of positive nodes was related inversely to prognosis with the optimal dichotomization between one to three (66% 5-year survival) and four or greater nodes (37% 5-year survival).     

Prediction of metastasis from low-malignant breast cancer by gene expression profiling

Promising results for prediction of outcome in breast cancer have been obtained by genome wide gene expression profiling. Some studies have suggested that an extensive overtreatment of breast cancer patients might be reduced by risk assessment with gene expression profiling. A patient group hardly examined in these studies is the low-risk patients for whom outcome is very difficult to predict with currently used methods. These patients do not receive adjuvant treatment according to the guidelines of the Danish Breast Cancer Cooperative Group (DBCG). In this study, 26 tumors from low-risk patients were examined with gene expression profiling. An intermediate risk group of 34 low-malignant T2 tumors that fulfilled all other low-risk criteria than tumor size was included to increase statistical power. A 32-gene classifier, HUMAC32, was identified and it predicted metastases with 80% sensitivity and 77% specificity. The classifier was also validated in an independent group of high-risk tumors resulting in comparable performance of HUMAC32 and a 70-gene classifier developed for this group. Furthermore, the 70-gene signature was tested in our low- and intermediate-risk samples. The results demonstrated high cross-platform consistency of the classifiers. Higher performance of HUMAC32 was demonstrated among the low-malignant cancers compared with the 70-gene classifier. This suggests that although the metastatic potential to some extend is determined by the same genes in groups of tumors with different characteristics and risk, expression-based classification specifically developed in low-risk patients have higher predictive power in this group.     

Molecular pharmacology of cancer therapy in human colorectal cancer by gene expression profiling

Global gene expression profiling has potential for elucidating the complex cellular effects and mechanisms of action of novel targeted anticancer agents or existing chemotherapeutics for which the precise molecular mechanism of action may be unclear. In this study, decreased expression of genes required for RNA and protein synthesis, and for metabolism were detected in rectal cancer biopsies taken from patients during a 5-fluorouracil infusion. Our observations demonstrate that this approach is feasible and can detect responses that may have otherwise been missed by conventional methods. The results suggested new mechanism-based combination treatments for colorectal cancer and demonstrated that expression profiling could provide valuable information on the molecular pharmacology of established and novel drugs.     

Thymidylate synthase expression in stage II and III colon cancer: a retrospective review.

This study is a retrospective analysis of thymidylate synthase (TS) levels in patients with stage II (T3 or T4) and III colon cancer. Two groups of patients were identified: one undergoing surgery alone (98 patients) and the second receiving adjuvant 5-fluorouracil chemotherapy (112 patients). TS analyses were carried out using the 106 monoclonal antibody and a published grading system dividing staining into high and low intensity. The distribution of patients with low versus high TS levels was similar in the two groups. There was no association between TS staining intensity and grade, stage or location of primary. Seventy-nine patients have relapsed: 46 (48%) in the surgery only group, 33 (30%) in the adjuvant therapy group (median follow-up: 51 and 61 months). Similar proportions relapsed when analyzed according to TS: in the surgery only group, 41% of patients with low TS, 48% with high TS; in the adjuvant group, 31% with low TS, 30% with high TS. In the surgery only group, a trend toward improved disease-free survival (DFS) was seen in the low TS group (84 versus 63% at 2 years, p = 0.08). No difference was seen in overall survival. There were no differences in DFS or overall survival in patients receiving adjuvant therapy according to TS intensity. The trend for worse outcome in patients with high TS is consistent with previous reports. The lack of difference in outcome for patients with low and high TS receiving chemotherapy suggests that high TS levels may predict greater benefit from adjuvant treatment.     

乳腺癌基因表达谱研究进展

乳腺癌是分子表达差异显著的一组疾病,乳腺癌临床异质性源自分子异质性.根据基因表达谱研究开发的分子标签,如70-基因标签、21-基因标签、乳腺癌分子分型标签等,在预测乳腺癌患者预后、指导临床治疗决策方面,表现出良好的应用价值和前景.     

Gene expression profiling of colon cancer by DNA microarrays and correlation with histoclinical parameters

Different diagnostic and prognostic groups of colorectal carcinoma (CRC) have been defined. However, accurate diagnosis and prediction of survival are sometimes difficult. Gene expression profiling might improve these classifications and bring new insights into underlying molecular mechanisms. We profiled 50 cancerous and noncancerous colon tissues using DNA microarrrays consisting of approximately 8000 spotted human cDNA. Global hierarchical clustering was to some extent able to distinguish clinically relevant subgroups, normal versus cancer tissues and metastatic versus nonmetastatic tumours. Supervised analyses improved these segregations by identifying sets of genes that discriminated between normal and tumour tissues, tumours associated or not with lymph node invasion or genetic instability, and tumours from the right or left colon. A similar approach identified a gene set that divided patients with significantly different 5-year survival (100% in one group and 40% in the other group; P=0.005). Discriminator genes were associated with various cellular processes. An immunohistochemical study on 382 tumour and normal samples deposited onto a tissue microarray subsequently validated the upregulation of NM23 in CRC and a downregulation in poor prognosis tumours. These results suggest that microarrays may provide means to improve the classification of CRC, provide new potential targets against carcinogenesis and new diagnostic and/or prognostic markers and therapeutic targets.