Adherence to guidelines for the referral of patients with colorectal cancer and abnormal tumour tissue testing for assessment of Lynch syndrome.

Background: To determine the proportion of patients with colorectal cancer and abnormal immunohistochemistry testing of tumour tissue who were referred to a cancer genetic clinic for genetic counselling and possible germline testing of a blood sample for Lynch syndrome.

Methods: This is a retrospective cohort study of patients with colorectal cancer and abnormal immunohistochemistry tumour tissue testing from St Vincent's Hospital (between November 2007 and December 2016). Patient list was compared against a state-wide database TrakGene to ascertain the overall referral rate for these patients.

Results: Of 216 patients, the total referral rate was 33.8% (n = 73), of which 27.8% (n = 60) were referred to St Vincent's Hospital's Cancer Genetics Service, 6% (n = 13) were referred externally and the remaining 66.2% (n = 143) were not referred. Binomial regression analysis performed displayed that age influenced likelihood of referral, where patients were 7.7% more likely to be referred for every decreasing year in age (P = 0.0004). Some clinicians were 4.3 times more likely to refer patients compared to others (P = 0.002).

Conclusion: Suboptimal patient uptake for cancer genetics evaluation was found. Identifying barriers to patient referral should lead to changes that increase patient referrals. This will ensure that patients receive adequate education, counselling and management of Lynch syndrome. It would also allow for the identification of further at-risk relatives for whom preventative strategies can be employed. In addition, identification of relatives not at risk by genetic testing will liberate them from unnecessary colonoscopies. Discussion with the clinicians involved has since allowed for copies of the immunohistochemistry results to be forwarded by the Pathology Department to the Cancer Genetics Unit for checking and follow up with the clinician to ensure that their patients are aware of the result and have been offered referral for cancer genetic evaluation. This process is subject to ongoing audit.