Screening guidelines have been updated to reflect the importance of family history as a risk factor for developing bowel cancer
Greater scrutiny of patients’ family history is the key to more appropriate bowel cancer screening, experts say.
Professor Mark Jenkins, director of the Centre for Epidemiology and Biostatistics at the University of Melbourne, led the update of the guidelines from 2005.
He and his colleagues published a summary of the guidelines in the MJA to draw attention to the importance of family history as a risk factor for developing bowel cancer, and in particular which details of the family history are important.
“Most [previous] screening guidelines recommend screening to begin at age 50 years for all risk categories or 10 years before the youngest age of colorectal cancer diagnosis in a relative, without explicitly considering risk of cancer for age and family history,” Professor Jenkins and his colleagues wrote.
Instead, what they recommend is that doctors try to drill down into the specifics of a patient’s family history. This included asking whether the affected family member was a first or second degree relative and how old they were when they were diagnosed (over or under age 55), Professor Jenkins said.
While it was common for patients to not know the specifics of their family history, asking them to estimate their age at diagnosis, or even asking relatives themselves would be helpful to guide screening recommendations, Professor Jenkins told The Medical Republic.
The new guidelines recommend risk be stratified into three categories, based on the patient’s family history and excluding those rare patients with a known high-risk genetic anomaly, such as Lynch syndrome, who would managed according to different, specific guidelines.
Those with an average risk (category 1) have no first-degree relatives with the cancer. They are recommended to have an iFOBT every two years, between the ages of 50 and 74, as per the National Bowel Cancer Screening program.
If they do have a first degree relative, or one first and one second degree relative, who were diagnosed at age 55 or older, then they are still categorised as average risk but should be considered for an iFOBT every two years starting at age 45.
Those with a moderately increased risk (category 2) would have one first-degree relative who was diagnosed with it before age 55, or two first degree or one first degree and at least two second degree relatives diagnosed at any age.
They are recommended to have an iFOBT every two years between ages 40 and 49, and then colonoscopies every five years until age 74.
Those at a high risk (category 3) have three first-degree relatives with the bowel cancer, or three second degree relatives diagnosed with the cancer and at least one of those before age 55.
They should have an iFOBT every two years starting age 35 to 44, and then a colonoscopy every five years until age 74.
It may be that people with a family history should be screened beyond the age of 74 years, but as yet, there is no health economic data to say whether the benefits outweigh the risks, the authors said.
MJA 2018; online 29 October
