Clinicians who order genetic testing for cancer need to understand its complexities and implications, experts warn.

Writing in a perspective article in the MJA Associate Professor Judy Kirk, Head of the Familial Cancer Service at Westmead Hospital in Sydney, and colleagues note that traditionally genetic testing for cancer has been offered through family cancer clinics and genetics services that also provided expert genetic counselling.

However Medicare item numbers for genetic testing introduced last year mean that any specialist or consultant physician can now order genetic testing for breast and ovarian cancer under certain criteria.

Professor Kirk and colleagues stress that while the proven benefits to selected families underscore the importance of broadening the availability of testing, it is essential that “any clinician who orders breast cancer genetic testing understands the complexities and implications generated.”

For example, many families with a strong family history [of cancer] for which there must be some genetic cause, do not have the gene identified through testing.

“Limitations in knowledge and technology need to be understood, and individuals from these families remain at potentially high risk. Such uninformative results require careful counselling so that families (and their clinicians) are not falsely reassured by the “no mutation found” result,” the authors caution.

Furthermore, they note that only 5% of female breast cancers, 15% of invasive epithelial ovarian cancers and up to 14% of breast cancers are related to BRCA1 or BRCA2 mutations, meaning that most patients with breast cancer do not need or will not benefit from a genetic test.

It is therefore imperative that non-genetic specialists ordering the tests “receive appropriate education and support to enable safe, evidence-based practice in keeping pace with the genomics revolution,” they write.

“This will be optimised if ordering clinicians develop a close relationship with a local family cancer clinic or clinical genetics service, which are ideally placed, and willing, to educate and support non-genetic practitioners in the transition to mainstream genetic testing,” they add.