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Results are delivered to you by your preferred method approximately 4 weeks after the patient has their blood collected.
Colorectal cancer is the third most common type of newly diagnosed cancer in Australia. It is estimated that 30% of patients with colorectal cancer have a family history of the disease, and up to 10% have genomic variants associated with inherited cancer syndromes including Lynch syndrome and familial adenomatous syndromes FAP and MAP.
MBS rebated diagnostic and predictive testing for the genes associated with these syndromes is now available for patients who meet criteria and when requested by a specialist medical practitioner. Guidelines recommend anyone with a Lynch syndrome risk of ≥5% as calculated by risk prediction models have germline testing however, MBS guidelines require a risk of ≥10%.
Detection of pathogenic variants in genes associated with inherited colorectal cancer syndromes:
Lynch syndrome is one of the most common cancer predisposition syndromes, and confers a significantly increased lifetime risk of colorectal cancer, endometrial cancer and multiple other cancers. A diagnosis of Lynch Syndrome is confirmed by the detection of a pathogenic germline variant in one of the MMR genes (MLH1, MSH2, MSH6 and PMS2) or the EPCAM gene. These are found in our Lynch syndrome panel.
Familial adenomatous polyposis is an autosomal dominant disorder characterised by numerous (>100 to 1000s) gastrointestinal adenomatous polyps that almost inevitably progress to CRC by age 40. A variant of the disorder, attenuated FAP, has a later onset, fewer polyps (usually <100) and reduced occurrence of extra-intestinal manifestations. Both forms of FAP are caused by pathogenic variants of the APC gene. Up to one third of cases are due to de novo (new) variants and therefore have no family history of disease.
MUTYH-associated polyposis is an autosomal recessive disorder characterized by attenuated adenomatous colorectal polyposis (usually 15-100 polyps) and significantly increased lifetime risk of colorectal cancer. MAP is caused by biallelic pathogenic variants of the MUTYH gene.
The APC and MUTYH genes are both found in our FAP/MAP panel.
Genetic testing for inherited cancer is a complex process that generates results that can have significant medical and psychological implications for patients and their families. As part of our laboratory accreditation, Genomic Diagnostics must ensure that patients receive appropriate genetic counselling for this type of testing.
Genetic counselling involves discussing benefits, limitations and the possible consequences of the genetic testing to be performed. It can be provided by a specialist or a qualified genetic counsellor and must be undertaken before the patient undergoes testing.
Strategies to identify individuals at risk of Lynch syndrome or individuals who should have germline testing for Lynch syndrome have evolved over time. Prediction models are evidence-based tools that use personal and family history to determine the risk that an individual is a carrier of a pathogenic variant in a gene associated with Lynch syndrome.
The models available for Lynch syndrome are:
The Medicare schedule currently contains three item numbers relevant to inherited colorectal cancer syndromes.
These are only rebatable if requested through a specialist and if the patient meets the criteria set out in them.
In summary:
MBS #73354 – diagnostic testing for Lynch syndrome in individuals with colorectal or endometrial cancer. In colorectal cancer, the patient must have demonstrated loss by IHC of MMR protein in solid tumour tissue. In endometrial cancer, the patient must be at a risk of >10% of having Lynch syndrome.
MBS # 73355 – diagnostic testing for individuals with FAP/MAP where the patient is assessed as being at a risk of >10% of having FAP or MAP.
MBS #73357 – predictive familial cancer test for a single gene variant where a family member has been identified as having this variant. A report from the family member stating the exact details of the variant must be supplied.