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Colorectal Cancer

Colorectal Cancer (CRC) Molecular Biomarkers 

International guidelines recommend testing for hotspot mutations in the rat sarcoma viral oncogene homolog (RAS) gene family, including the Kirsten RAS (KRAS) and neuroblastoma RAS (NRAS) proto-oncogenes, to exclude RAS mutation-positive metastatic colorectal cancer (mCRC) patients from receiving anti-epidermal growth factor receptor (EGFR) therapy.

This is because anti-EGFR agents do not provide meaningful survival benefits versus anti-angiogenic/chemotherapy regimens in mCRC patients whose tumours are not wild type (WT) with respect to RAS genes 1,2.

Mutations in proto-oncogene, KRAS, are detected in up to 40% of CRC patients. The activated KRAS gene contributes significantly to several aspects of the tumour growth, including tumour survival, angiogenesis, proliferation and metastasis. It is therefore vital that the KRAS mutation status of a patient’s colorectal tumour can be detected to allow patients access to treatment for which there is an increased likelihood
of benefit 3.

BRAF mutations occur in 15% of colorectal cancers. BRAF mutational status is used as a strong predictor for overall survival (OS) at all stages of disease; patients with BRAF-mutated CRC have a generally poor prognosis.

Traditionally, formalin-fixed paraffin-embedded (FFPE) tumour samples have been used to determine the RAS mutation status of CRC patients in routine clinical practice. 

References:
1. Bos JL et al., (1987) Nature 327(6120):293–297.
2. Van Cutsem E et al., (2009) N Engl J Med 360(14):1408–1417
3. Bokemeyer C et al., (2009) J Clin Oncol 27(5):663–671.



Somatic Mutation | Solid Tissue Molecular Profiling in Colorectal Cancer

Colorectal Cancer Solid Tissue Gene Panel

Testing for mutations in KRAS and NRAS in metastatic colorectal tumour tissue may assist in assessing which patients will likely benefit from anti-EGFR therapeutics, such as Cetuximab or Panitumumab.

The colorectal cancer (CRC) gene panel detects mutations within oncogenes that are frequently
mutated in CRC. 

Gene panel includes:

KRAS PIK3CA
NRAS PTEN
BRAF AKT1

When to Order: At diagnosis for treatment selection.
How to Order: Fill out our Somatic Mutation testing request form and tick the Somatic Mutation test panel required.
Turnaround Time: 5–7 business days from the sample receipt date.
Specimen Required: Formalin-fixed paraffin-embedded (FFPE) tissue of a solid colorectal cancer tumour.
Test Cost: Medicare rebate available if criteria is met. If criteria is not met there is an out-of-pocket fee of $400.

A negative result does not rule out the presence of a mutation that may be present but below the limits of detection for this assay (<5%).

Download Somatic Mutation Brochure

Download Somatic Mutation Request Form Download Somatic Mutation Request Form (WA)



Aspect ctDNA Liquid Biopsy in Colorectal Cancer 


In colorectal cancer, ctDNA could also be used to track clonal evolution and targeted drug responses 1,2.

In patients with metastatic colorectal cancer who developed resistance to EGFR antibodies, analysis of ctDNA identified the emergence of polyclonal and heterogeneous patterns of mutation in KRAS, NRAS, BRAF, or EGFR with mutations found in 96% of panitumumab- or cetuximab refractory patients. Subsequently, Misale et al. were able to illustrate a way to use this information to overcome treatment resistance 3,4,5.

Furthermore, studies demonstrate better outcomes when no tumour-derived DNA is found in patients following surgery or chemotherapy in colorectal cancer patients, whereas those with whom tumour DNA is still present do better with the addition of more aggressive and targeted treatment or chemotherapy 6.

Colorectal Cancer ctDNA Gene Panel

The Aspect Liquid Biopsy colorectal cancer (CRC) ctDNA gene panel can detect DNA alterations in patients’ plasma that guide treatment decisions as detailed below.

Gene panel includes:

  • KRAS: 48 mutations across exon 2, 3 and 4
  • NRAS: 40 mutations across exon 2, 3 and 4
  • BRAF: 5 mutations across exon 11 and 15
  • PIK3CA: 4 mutations across exon 9 and 20
  • EGFR (T790M NOT included): 10 extracellular mutations across exon 12

When to Order: At diagnosis or to monitor treatment resistance or early relapse.
How to Order: Health practitioners can order Aspect Liquid Biopsy for cancer patients using the Aspect Liquid Biopsy request form.
Turnaround Time: 5–7 business days from the sample receipt date.
Specimen Required: This test requires TWO 10ml blood samples (special tubes), which can be taken at any of our collection centres.
Test Cost: No Medicare rebate available. An out-of-pocket fee of $550 applies.

A negative result does not rule out the presence of a mutation that may be present but below the limits of detection for this assay (<2%).

References:
1. Gray E et al., (2015) Oncotarget 6 (39):42008–42018.
2. Girotti M et al., (2016) Cancer Discov 6 (3):286–299.
3. Bettegowda C et al., (2014) Sci Transl Med 6:224ra24.
4. Misale S et al., (2012) Nature 486(7404):532–536.
5. Misale S et al., (2014) Sci Transl Med 6:224ra26.
6. Tie J et al., (2016) Sci Transl Med 8:346ra92.

"Rapid" (48-hr) ctDNA KRAS Mutation Analysis

Used to detect a single gene target, KRAS, of circulating tumour DNA (ctDNA) in a patient’s blood, within a 48-hour turnaround from sample receipt.

Gene panel includes:

  • KRAS mutation test
    - Exon 2 codons 12 (variants G12C, G12R, G12S, G12A, G12D, G12V)
    & 13 (G13D)

When to Order: At diagnosis or to monitor treatment resistance or early relapse.
How to Order: Health practitioners can order Aspect Liquid Biopsy for cancer patients using the Aspect Liquid Biopsy request form.
Turnaround Time: 48 business hours from the sample receipt date.
Specimen Required: This test requires TWO 10ml blood samples (special tubes), which can be
taken at any of our collection centres.
Test Cost: No Medicare rebate available. An out-of-pocket fee of $550 applies.

A negative result does not rule out the presence of a mutation that may be present but below the limits of detection for this assay (<1%).

Download Aspect Liquid Biopsy Doctor BrochureDownload Aspect Liquid Biopsy Patient Brochure

Download Aspect Liquid Biopsy Request Form



The content on our Molecular Cancer Services page is written by National Clinical Director of Molecular Genetic Pathology at Australian Clinical Labs, Associate Professor Mirette Saad

 

Assoc. Prof. Mirette Saad

MBBS (Hons), MD, MAACB, FRCPA, PhD
Lab: Clayton
Speciality: Chemical Pathology and Molecular Genetics
Areas Of Interest: Cancer Genetics, Antenatal Screening, NIPT, Endocrine, Fertility Testing and Research, Medical Teaching
Phone: 1300 134 111
Email: mirette.saad@clinicallabs.com.au

Associate Professor Mirette Saad is a Consultant Chemical Pathologist and the National Clinical Director of Molecular Genetic Pathology at Australian Clinical Labs. Associate Professor Saad obtained her fellowship in Chemical and Molecular Pathology with a clinical Microbiology sub-specialty in Egypt.

After several posts, she worked as a Medical Laboratory Director in private labs and as an Associate Professor and Examiner of Clinical Chemistry for postgraduate and undergraduate medical and nursing students at various institutions. Upon receiving the National Health and Medical Research (NHMRC) Scholarship in 2006, Associate Professor Saad commenced her PhD studies at Melbourne University and Peter MacCallum Cancer Institute in Cancer Genetics. Associate Professor Saad undertook her specialty training at Healthscope Pathology (now Australian Clinical Labs) and Monash Health and obtained the Chemical Pathology Fellowship (FRCPA) and the Membership (MAACB) by examination from the Royal College of Pathologists of Australasia (RCPA) and the Australasian Association of Clinical Biochemists (AACB) respectively.

She is currently a member of the Chemical Pathology Advisory Committee at RCPA. At Clinical Labs, A/P Saad supervises the antenatal screening program including combined First Trimester Screening and Non-Invasive Prenatal Testing (NIPT) along with the Molecular Genetic testing for hereditary disorders, personalised drug therapy and cancer.

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