KRAS Mutation Screening

The prognosis for patients with metastatic colorectal cancer has significantly improved due to the introduction of new treatments that target the epidermal growth factor receptor (EGFR). However, not all patients benefit from these treatments. It has recently been found that in patients with metastatic colorectal cancer, EGRF targeted treatment is only effective in those patients who have a normal (or wild-type) kRAS gene within their tumour.

KRAS mutation analysis has become part of the standard care in patients treated with EGFR targeted treatment. A number of studies have demonstrated that in patients with metastatic colorectal cancer the addition of either cetuximab or panitumumab as monotherapy or in combination with chemotherapy increases the progression free survival. However, only patients without a mutation in the kRAS gene benefit from this treatment.

Specimen Required:

Formalin-fixed paraffin embedded tissue containing at least 20% tumour is required. Either of the following is acceptable.

    1. The entire tissue block can be sent which will be sectioned, macro-dissected and processed, then returned following analysis.

    2. Eight, seven micron unstained sections on labelled glass slides, together with one H&E stained section.

Assay Performed: Twice per week
Medicare Rebate: No

References:

Amado RG et al (2008) Wild-type kRAS is required for panitumumab efficacy in patients with metastatic colorectal cancer. J Clin Oncol 26: 1626-1634.
DeRoock W et al (2008) kRAS sild-type state predicts survival and is associated to early radiological response in metastatic colorectal cancer treated with cetuximab. Ann Oncol 19: 508-515.

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