Canadian Expert Group consensus recommendations: KRAS testing in colorectal cancer

The ideal reporting of RAS testing in colorectal adenocarcinoma: a pathologists' perspective

RAS gene mutational status represents an imperative predictive biomarker to be tested in the clinical management of metastatic colorectal adenocarcinoma. Even if it is one of the most studied biomarkers in the era of precision medicine, several pre-analytical and analytical factors may still impasse an adequate reporting of RAS status in clinical practice, with significant therapeutic consequences. Thus, pathologists should be aware on the main topics related to this molecular evaluation: (i) adopt diagnostic limit of detections adequate to avoid the interference of sub-clonal cancer cell populations; (ii) choose the most adequate diagnostic strategy according to the available sample and its qualification for molecular testing; (iii) provide all the information regarding the mutation detected, since many RAS mutation-specific targeted therapeutic approaches are in development and will enter into routine clinical practice. In this review, we give a comprehensive description of the current scenario about RAS gene mutational testing in the clinic focusing on the pathologist's role in patient selection for targeted therapies.

Tumor Biomarker Testing for Metastatic Colorectal Cancer: a Canadian Consensus Practice Guideline

The systemic therapy management of metastatic colorectal cancer (mCRC) has evolved from primarily cytotoxic chemotherapies to now include targeted agents given alone or in combination with chemotherapy, and immune checkpoint inhibitors. A better understanding of the pathogenesis and molecular drivers of colorectal cancer not only aided the development of novel targeted therapies but led to the discovery of tumor mutations which act as predictive biomarkers for therapeutic response. Mutational status of the KRAS gene became the first genomic biomarker to be established as part of standard of care molecular testing, where KRAS mutations within exons 2, 3, and 4 predict a lack of response to anti- epidermal growth factor receptor therapies. Since then, several other biomarkers have become relevant to inform mCRC treatment; however, there are no published Canadian guidelines which reflect the current standards for biomarker testing. This guideline was developed by a pan-Canadian advisory group to provide contemporary, evidence-based recommendations on the minimum acceptable standards for biomarker testing in mCRC, and to describe additional biomarkers for consideration.

Defining the Criteria for Reflex Testing for BRAF Mutations in Cutaneous Melanoma Patients

Targeted therapy has been developed through an in-depth understanding of molecular pathways involved in the pathogenesis of melanoma. Approximately ~50% of patients with melanoma have tumors that harbor a mutation of the BRAF oncogene. Certain clinical features have been identified in BRAF-mutated melanomas (primary lesions located on the trunk, diagnosed in patients <50, visibly pigmented tumors and, at times, with ulceration or specific dermatoscopic features). While BRAF mutation testing is recommended for stage III-IV melanoma, guidelines differ in recommending mutation testing in stage II melanoma patients. To fully benefit from these treatment options and avoid delays in therapy initiation, advanced melanoma patients harboring a BRAF mutation must be identified accurately and quickly. To achieve this, clear definition and implementation of BRAF reflex testing criteria/methods in melanoma should be established so that patients with advanced melanoma can arrive to their first medical oncology appointment with a known biomarker status. Reflex testing has proven effective for a variety of cancers in selecting therapies and driving other medical decisions. We overview the pathophysiology, clinical presentation of BRAF-mutated melanoma, current guidelines, and present recommendations on BRAF mutation testing. We propose that reflex BRAF testing should be performed for every melanoma patient with stages ≥IIB.

Cost-Effectiveness of RAS Genetic Testing Strategies in Patients With Metastatic Colorectal Cancer: A Systematic Review

BACKGROUND

Monoclonal antibodies against epidermal growth factor receptor (EGFR) have proved beneficial for the treatment of metastatic colorectal cancer (mCRC), particularly when combined with predictive biomarkers of response. International guidelines recommend anti-EGFR therapy only for RAS (NRAS,KRAS) wild-type tumors because tumors with RAS mutations are unlikely to benefit.

OBJECTIVES

We aimed to review the cost-effectiveness of RAS testing in mCRC patients before anti-EGFR therapy and to assess how well economic evaluations adhere to guidelines.

METHODS

A systematic review of full economic evaluations comparing RAS testing with no testing was performed for articles published in English between 2000 and 2018. Study quality was assessed using the Quality of Health Economic Studies scale, and the British Medical Journal and the Philips checklists.

RESULTS

Six economic evaluations (2 cost-effectiveness analyses, 2 cost-utility analyses, and 2 combined cost-effectiveness and cost-utility analyses) were included. All studies were of good quality and adopted the perspective of the healthcare system/payer; accordingly, only direct medical costs were considered. Four studies presented testing strategies with a favorable incremental cost-effectiveness ratio under the National Institute for Clinical Excellence (£20 000-£30 000/QALY) and the US ($50 000-$100 000/QALY) thresholds.

CONCLUSIONS

Testing mCRC patients for RAS status and administering EGFR inhibitors only to patients with RAS wild-type tumors is a more cost-effective strategy than treating all patients without testing. The treatment of mCRC is becoming more personalized, which is essential to avoid inappropriate therapy and unnecessarily high healthcare costs. Future economic assessments should take into account other parameters that reflect the real world (eg, NRAS mutation analysis, toxicity of biological agents, genetic test sensitivity and specificity).

A retrospective observational study to estimate the attrition of patients across lines of systemic treatment for metastatic colorectal cancer in Canada

Background

Selection and sequencing of treatment regimens for individual patients with metastatic colorectal cancer (mcrc) is driven by maintaining reasonable quality of life and extending survival, as well as by access to and cost of therapies. The objectives of the present study were to describe, for patients with mcrc, attrition across lines of systemic therapy, patterns of therapy and their timing, and KRAS status.

Methods

A retrospective chart review at 6 Canadian academic centres included sequential patients who were diagnosed with mcrc from 1 January 2009 onward and who initiated first-line systemic treatment for mcrc between 1 January and 31 December 2009. Death was included as a competing risk in the analysis.

Results

The analysis included 200 patients who started first-line therapy. The proportions of patients who started second-, third-, and fourth-line systemic therapy were 70%, 30%, and 15% respectively. Chemotherapy plus bevacizumab was the most common first-line combination (66%). The most common first-line regimen was folfiri plus bevacizumab. KRAS testing was performed in 103 patients (52%), and 38 of 68 patients (56%, 19% overall) with confirmed KRAS wild-type tumours received an epidermal growth factor receptor inhibitor (egfri), which was more common in later lines. Most KRAS testing occurred after initiation of second-line therapy.

Conclusions

In the modern treatment era, a high proportion of patients receive at least two lines of therapy for mcrc, but only 19% receive egfri therapy. Earlier KRAS testing and therapy with an egfri might allow a greater proportion of patients to access all 5 active treatment agents.

Real-world use of trifluridine/tipiracil for patients with metastatic colorectal cancer in Canada

Background

Outcomes for patients with metastatic colorectal cancer (mcrc) are improving with the introduction of new treatments. Treatment for patients who are still fit after failure of all available therapies represents a significant unmet need. In the present study, we analyzed real-world treatment patterns for patients enrolled in Health Canada's trifluridine/tipiracil (ftd/tpi) Special Access Program (sap) and Taiho Pharma Canada's Patient Support Program (psp).

Methods

Demographic information and clinical treatment data were collected from adults with mcrc who were previously treated with, or were not candidates for, available therapies and who were enrolled in the sap and psp. For all patients, ftd/tpi treatment status, discontinuation reasons, and prior therapies were examined.

Results

The analysis included 717 Canadian patients enrolled in the ftd/tpi sap and psp from September 2017 to October 2018. In that cohort, 59.7% were men, median age was 65 years, and median duration of therapy was 77 days (25%-75% interquartile range: 43-106 days). Of treated patients, 67.1% maintained the same dose for the duration of therapy; 28.0% had a dose reduction.On multivariable analysis, duration of therapy was not influenced by sex, age, province, RAS mutation status, or prior therapies. However, prior oxaliplatin-based chemotherapy (capox or folfox) appeared to be associated with higher rates of discontinuation because of death or disease progression.

Conclusions

In advanced mcrc, ftd/tpi is a well-tolerated therapy. The large number of patients enrolled in the access programs within a short period of time is reflective of major clinical need in this area, with many patients being eligible and interested in pursuing treatment in the refractory setting.

Circulating Cell-Free Tumour DNA in the Management of Cancer

With the development of new sensitive molecular techniques, circulating cell-free tumour DNA containing mutations can be identified in the plasma of cancer patients. The applications of this technology may result in significant changes to the care and management of cancer patients. Whilst, currently, these "liquid biopsies" are used to supplement the histological diagnosis of cancer and metastatic disease, in the future these assays may replace the need for invasive procedures. Applications include the monitoring of tumour burden, the monitoring of minimal residual disease, monitoring of tumour heterogeneity, monitoring of molecular resistance and early diagnosis of tumours and metastatic disease.

Eprobe-mediated screening system for somatic mutations in the KRAS locus

Activating mutations in the Kirsten rat sarcoma viral oncogene homolog (KRAS) loci are largely predictive of resistance to epidermal growth factor receptor (EGFR) therapy in colorectal cancer (CRC). A highly sensitive detection system for the KRAS gene mutations is urgently needed; however, conventional methods have issues with feasibility and cost performance. Here, we describe a novel detection system using a fluorescence ‘Eprobe’ capable of detecting low level KRAS gene mutations, via real-time PCR, with high sensitivity and simple usability. We designed our Eprobes to be complementary to wild-type (WT) KRAS or to the commonly mutated codons 12 and 13. The WT Eprobe binds strongly to the WT DNA template and suppresses amplification by blocking annealing of the primer during PCR. Eprobe-PCR with WT Eprobe shows high sensitivity (0.05–0.1% of plasmid DNA, 1% of genomic DNA) for the KRAS mutation by enrichment of the mutant type (MT) amplicon. Assay performance was compared to Sanger sequencing using 92 CRC samples. Discrepancies were analyzed by mutation genotyping via Eprobe-PCR with full match Eprobes for 7 prevalent mutations and the next generation sequencing (NGS). Significantly, the Eprobe system had a higher sensitivity for detecting KRAS mutations in CRC patient samples; these mutations could not be identified by Sanger sequencing. Thus, the Eprobe approach provides for highly sensitive and convenient mutation detection and should be useful for diagnostic applications.

KRAS mutation analysis by PCR: a comparison of two methods

Background

KRAS mutation assays are important companion diagnostic tests to guide anti-EGFR antibody treatment of metastatic colorectal cancer. Direct comparison of newer diagnostic methods with existing methods is an important part of validation of any new technique. In this this study, we have compared the Therascreen (Qiagen) ARMS assay with Competitive Allele-Specific TaqMan PCR (castPCR, Life Technologies) to determine equivalence for KRAS mutation analysis.

Methods

DNA was extracted by Maxwell (Promega) from 99 colorectal cancers. The ARMS-based Therascreen and a customized castPCR assay were performed according to the manufacturer’s instructions. All assays were performed on either an Applied Biosystems 7500 Fast Dx or a ViiA7 real-time PCR machine (both from Life Technologies). The data were collected and discrepant results re-tested with newly extracted DNA from the same blocks in both assay types.

Results

Of the 99 tumors included, Therascreen showed 62 tumors to be wild-type (WT) for KRAS, while 37 had KRAS mutations on initial testing. CastPCR showed 61 tumors to be wild-type (WT) for KRAS, while 38 had KRAS mutations. Thirteen tumors showed BRAF mutation in castPCR and in one of these there was also a KRAS mutation. The custom castPCR plate included several other KRAS mutations and BRAF V600E, not included in Therascreen, explaining the higher number of mutations detected by castPCR. Re-testing of discrepant results was required in three tumors, all of which then achieved concordance for KRAS. CastPCR assay Ct values were on average 2 cycles lower than Therascreen.

Conclusion

There was excellent correlation between the two methods. Although castPCR assay shows lower Ct values than Therascreen, this is unlikely to be clinically significant.

Clinical practice guidelines and consensus statements in oncology--an assessment of their methodological quality

BACKGROUND

Consensus statements and clinical practice guidelines are widely available for enhancing the care of cancer patients. Despite subtle differences in their definition and purpose, these terms are often used interchangeably. We systematically assessed the methodological quality of consensus statements and clinical practice guidelines published in three commonly read, geographically diverse, cancer-specific journals. Methods Consensus statements and clinical practice guidelines published between January 2005 and September 2013 in Current Oncology, European Journal of Cancer and Journal of Clinical Oncology were evaluated. Each publication was assessed using the Appraisal of Guidelines for Research and Evaluation II (AGREE II) rigour of development and editorial independence domains. For assessment of transparency of document development, 7 additional items were taken from the Institute of Medicine's standards for practice guidelines and the Journal of Clinical Oncology guidelines for authors of guidance documents.

METHODS

Consensus statements and clinical practice guidelines published between January 2005 and September 2013 in Current Oncology, European Journal of Cancer and Journal of Clinical Oncology were evaluated. Each publication was assessed using the Appraisal of Guidelines for Research and Evaluation II (AGREE II) rigour of development and editorial independence domains. For assessment of transparency of document development, 7 additional items were taken from the Institute of Medicine's standards for practice guidelines and the Journal of Clinical Oncology guidelines for authors of guidance documents.

FINDINGS

Thirty-four consensus statements and 67 clinical practice guidelines were evaluated. The rigour of development score for consensus statements over the three journals was 32% lower than that of clinical practice guidelines. The editorial independence score was 15% lower for consensus statements than clinical practice guidelines. One journal scored consistently lower than the others over both domains. No journals adhered to all the items related to the transparency of document development. One journal's consensus statements endorsed a product made by the sponsoring pharmaceutical company in 64% of cases.

CONCLUSION

Guidance documents are an essential part of oncology care and should be subjected to a rigorous and validated development process. Consensus statements had lower methodological quality than clinical practice guidelines using AGREE II. At a minimum, journals should ensure that that all consensus statements and clinical practice guidelines adhere to AGREE II criteria. Journals should consider explicitly requiring guidelines to declare pharmaceutical company sponsorship and to identify the sponsor's product to enhance transparency.

Current approaches for predicting a lack of response to anti-EGFR therapy in KRAS wild-type patients

Targeting epidermal growth factor receptor (EGFR) has been one of the most effective colorectal cancer strategies. Anti-EGFR antibodies function by binding to the extracellular domain of EGFR, preventing its activation, and ultimately providing clinical benefit. KRAS mutations in codons 12 and 13 are recognized prognostic and predictive biomarkers that should be analyzed at the clinic prior to the administration of anti-EGFR therapy. However, still an important fraction of KRAS wild-type patients do not respond to the treatment. The identification of additional genetic determinants of primary or secondary resistance to EGFR targeted therapy for further improving the selection of patients is urgent. Herein, we review the latest published literature highlighting the most important genes that may predict resistance to anti-EGFR monoclonal antibodies in colorectal cancer patients. According to the available findings, the evaluation of BRAF, NRAS, PIK3CA, and PTEN status could be the right strategy to select patients who are likely to respond to anti-EGFR therapies. In the future, the combination of those biomarkers will help establish consensus that can be introduced into clinical practice.

Benefits, issues, and recommendations for personalized medicine in oncology in Canada

The burden of cancer for Canadian citizens and society is large. New technologies have the potential to increase the use of genetic information in clinical decision-making, furthering prevention, surveillance, and safer, more effective drug therapies for cancer patients. Personalized medicine can have different meanings to different people. The context for personalized medicine in the present paper is genetic testing, which offers the promise of refining treatment decisions for those diagnosed with chronic and life-threatening illnesses. Personalized medicine and genetic characterization of tumours can also give direction to the development of novel drugs. Genetic testing will increasingly become an essential part of clinical decision-making. In Canada, provinces are responsible for health care, and most have unique policies and programs in place to address cancer control. The result is inconsistency in access to and delivery of therapies and other interventions, beyond the differences expected because of demographic factors and clinical education. Inconsistencies arising from differences in resources, policy, and application of evidence-informed personalized cancer medicine exacerbate patient access to appropriate testing and quality care. Geographic variations in cancer incidence and mortality rates in Canada-with the Atlantic provinces and Quebec having higher rates, and British Columbia having the lowest rates-are well documented. Our purpose here is to provide an understanding of current and future applications of personalized medicine in oncology, to highlight the benefits of personalized medicine for patients, and to describe issues and opportunities for improvement in the coordination of personalized medicine in Canada. Efficient and more rapid adoption of personalized medicine in oncology in Canada could help overcome those issues and improve cancer prevention and care. That task might benefit from the creation of a National Genetics Advisory Panel that would review research and provide recommendations on tests for funding or reimbursement, guidelines, service delivery models, laboratory quality assurance, education, and communication. More has to be known about the current state of personalized cancer medicine in Canada, and strategies have to be developed to inform and improve understanding and appropriate coordination and delivery. Our hope is that the perspectives emphasized in this paper will stimulate discussion and further research to create a more informed response.

Recommendations from the EGAPP Working Group: can testing of tumor tissue for mutations in EGFR pathway downstream effector genes in patients with metastatic colorectal cancer improve health outcomes by guiding decisions regarding anti-EGFR therapy?

SUMMARY OF RECOMMENDATIONS

The Evaluation of Genomic Applications in Practice and Prevention (EGAPP) Working Group (EWG) found that, for patients with metastatic colorectal cancer (mCRC) who are being considered for treatment with cetuximab or panitumumab, there is convincing evidence to recommend clinical use of KRAS mutation analysis to determine which patients are KRAS mutation positive and therefore unlikely to benefit from these agents before initiation of therapy. The level of certainty of the evidence was deemed high, and the magnitude of net health benefit from avoiding potentially ineffective and harmful treatment, along with promoting more immediate access to what could be the next most effective treatment, is at least moderate.The EWG found insufficient evidence to recommend for or against BRAF V600E testing for the same clinical scenario. The level of certainty for BRAF V600E testing to guide antiepidermal growth factor receptor (EGFR) therapy was deemed low. The EWG encourages further studies of the potential value of testing in patients with mCRC who were found to have tumors that are wild type (mutation negative) for KRAS to predict responsiveness to therapy.The EWG found insufficient evidence to recommend for or against testing for mutations in NRAS, or PIK3CA, and/or loss of expression of PTEN or AKT proteins. The level of certainty for this evidence was low. In the absence of supporting evidence, and with consideration of other contextual issues, the EWG discourages the use of these tests in guiding decisions on initiating anti-EGFR therapy with cetuximab or panitumumab unless further evidence supports improved clinical outcomes.

RATIONALE

It has been suggested that patients with mCRC whose tumors harbor certain mutations affecting EGFR pathway signaling are typically unresponsive to therapy with anti-EGFR antibodies (cetuximab and panitumumab). The EWG identified recent evidence reviews that have addressed this topic, and this recommendation statement is based on results of these reviews. In developing these recommendations the EWG considered evidence in the areas described below.

ANALYTIC VALIDITY

Although no research syntheses that have formally evaluated analytic validity of these tests were found, the EWG was able to draw the following conclusions from assessments included in the evidence reviews under consideration. There is adequate evidence that KRAS mutation analysis reliably and accurately detects common mutations (codons 12 and 13), whereas evidence was inadequate for less frequent KRAS mutations (e.g., codon 61). There is also adequate evidence that testing for BRAF V600E accurately and reliably detects the mutation. For common mutations in NRAS, PIK3CA, and expression of PTEN AKT, there is adequate evidence of accurate and reliable detection. However, much less data exist in support. Furthermore, in the specific context of mCRC, no evidence was found on the analytic validity of immunohistochemistry (IHC) assays for PTEN or AKT expression.

CLINICAL VALIDITY

For KRAS mutation analysis, the EWG found convincing evidence for association with treatment response to anti-EGFR therapy, independent of prognostic association. For BRAF V600E mutation testing, the EWG found insufficient evidence for association with treatment response to anti-EGFR therapy independent of prognostic association. The EWG found insufficient evidence for association of results of testing for mutations in NRAS or PIK3CA, and loss of expression of PTEN or ATK proteins, with treatment response to anti-EGFR therapy.

CLINICAL UTILITY

For KRAS mutation analysis, the EWG found adequate evidence that improved health outcomes are achieved by avoiding ineffective chemotherapy and potential side effects and expediting access to the next most effective treatment. Inadequate evidence was found regarding association of BRAF V600E mutation testing or loss of PTEN expression with improved health outcomes among patients with mCRC undergoing anti-EGFR therapy as compared with patients with tumors bearing wild-type BRAF sequence and PTEN expression levels, respectively. No evidence was found to support improved health outcomes associated with testing results for NRAS or PIK3CA variants, or AKT protein expression levels in this clinical scenario.

CONTEXTUAL ISSUES

CRC is an important and highly prevalent health problem. Improvements in mCRC outcomes associated with pharmacogenetic testing could have important clinical, and potentially public health, impacts. Adverse events related to cancer chemotherapy can be common and severe. Therefore, successfully optimizing treatment to maximize efficacy and minimize side effects is important for reducing mCRC-related morbidity and mortality.

Targeted therapies in colorectal cancer-an integrative view by PPPM

In developed countries, colorectal cancer (CRC) is the third most common malignancy, but it is the second most frequent cause of cancer-related death. Clinicians are still faced with numerous challenges in the treatment of this disease, and future approaches which target the molecular features of the disorder will be critical for success in this disease setting. Genetic analyses of many solid tumours have shown that up to 100 protein-encoding genes are mutated. Within CRC, numerous genetic alterations have been identified in a number of pathways. Therefore, understanding the molecular pathology of CRC may present information on potential routes for treatment and may also provide valuable prognostic information. This will be particularly pertinent for molecularly targeted treatments, such as anti-vascular endothelial growth factor therapies and anti-epidermal growth factor receptor (EGFR) monoclonal antibody therapy. KRAS and BRAF mutations have been shown to predict response to anti-EGFR therapy. As EGFR can also signal via the phosphatidylinositol 3-kinase (PI3K) kinase pathway, there is considerable interest in the potential roles of members of this pathway (such as PI3K and PTEN) in predicting treatment response. Therefore, a combined approach of new techniques that allow identification of these biomarkers alongside interdisciplinary approaches to the treatment of advanced CRC will aid in the treatment decision-making process and may also serve to guide future therapeutic approaches.

KRAS mutation testing in metastatic colorectal cancer

The KRAS oncogene is mutated in approximately 35%-45% of colorectal cancers, and KRAS mutational status testing has been highlighted in recent years. The most frequent mutations in this gene, point substitutions in codons 12 and 13, were validated as negative predictors of response to anti-epidermal growth factor receptor antibodies. Therefore, determining the KRAS mutational status of tumor samples has become an essential tool for managing patients with colorectal cancers. Currently, a variety of detection methods have been established to analyze the mutation status in the key regions of the KRAS gene; however, several challenges remain related to standardized and uniform testing, including the selection of tumor samples, tumor sample processing and optimal testing methods. Moreover, new testing strategies, in combination with the mutation analysis of BRAF, PIK3CA and loss of PTEN proposed by many researchers and pathologists, should be promoted. In addition, we recommend that microsatellite instability, a prognostic factor, be added to the abovementioned concomitant analysis. This review provides an overview of KRAS biology and the recent advances in KRAS mutation testing. This review also addresses other aspects of status testing for determining the appropriate treatment and offers insight into the potential drawbacks of mutational testing.

Different metastatic pattern according to the KRAS mutational status and site-specific discordance of KRAS status in patients with colorectal cancer

Background

We evaluated the association between a KRAS mutational status and various clinicopathologic features including the metastatic pattern in patients with metastatic or recurrent colorectal cancer (MRCRC). The concordance rates of the KRAS status between primary tumor sites and paired metastatic organs were also analyzed.

Methods

The KRAS mutational status in codons 12, 13, and 61 from formalin-fixed sections of both primary tumors and related metastases was determined by sequencing analysis. One hundred forty-three Korean patients with MRCRC with available tissues (resection or biopsy) from both primary tumors and related metastatic sites were consecutively enrolled.

Results

The KRAS mutation rate was 52.4% (75/143) when considering both the primary and metastatic sites. When the relationship between the KRAS status and initial metastatic sites at the time of diagnosis of MRCRC was analyzed, lung metastasis was more frequent as the initial metastatic site in patients with the KRAS mutation than in patients without the KRAS mutation (45.3% vs. 22.1%; P = 0.003). However, liver (37.3% vs. 70.6%; P < 0.001) or distant lymph node metastases (6.7% vs. 19.1%; P = 0.025) were less frequent as the initial metastatic organ in patients with the KRAS mutation than in patients without the KRAS mutation. The discordance rate of KRAS mutational status between primary and paired metastatic sites other than the lung was 12.3% (13/106). Compared with primary tumor sites, the KRAS discordance rate was significantly higher in matched lung metastases [32.4% (12/37)] than in other matched metastatic organs (P = 0.005).

Conclusions

Organs initially involved by distant metastasis were different according to the KRAS mutational status in MRCRC patients. The concordance rate (87.7%) of the KRAS mutation status at metastatic sites other than the lung was generally high compared with primary tumor sites; however, lung metastasis had a high rate of KRAS discordance (32.4%).

Predictive Molecular Tumour Testing: What Are the Obstacles between Bench and Bedside?

There have been many exciting new breakthroughs in understanding tumour biology. This has opened up the possibility of personalized treatment for people with certain tumours. The epidermal growth factor receptor (EGFR) and K-ras are two such targets that can help classify tumours on a molecular basis and guide treatment decisions. However, there are still questions about how best to implement new molecular tests like these to characterize tumours in clinical practice. Potential obstacles include availability of good quality tissue specimens, access to the right test, and consensus about interpretation, funding, and availability. In this paper, we review these issues, by discussing these two examples in detail and suggest some actions for addressing potential barriers.