Clinicians are being reminded about changes to the Clinical practice guidelines for the prevention, early detection and management of colorectal cancer regarding family history.
Revised guidelines in people with a family history of the disease have separated out those with a suspected or known genetic syndrome such as Lynch syndrome.
As such recommendations relevant for genetic syndromes – screening 10 years before the earliest diagnosis in the family – are no longer relevant for other individuals with a family history.
Professor Mark Jenkins, director of the Centre for Epidemiology and Biostatistics in the University of Melbourne’s School of Population and Global Health, told the limbic people with known or potential genetic syndromes need much more intensive screening.
“The novel aspect of these guidelines, is that when the patient’s age is very low, in their 30s and 40s, even if the family history is severe enough, FOBT is appropriate rather than colonoscopy for at least those first five or ten years.”
“Because their risk is roughly equivalent to the average population risk at age 50, all we are doing is winding back the age at which standard screening should begin. Once they reach age 50, they should be going onto more intensive colonoscopy.”
According to the guideline summary published in the MJA, individuals in the highest risk category – those with at least three first degree relatives diagnosed at any age or those with at least three first or second degree relatives including at least one diagnosed before age 55 years – have a risk about 7-10 times the average population risk.
Screening guidelines for this group of individuals are now biennial immunochemical FOBT (iFOBT) from age 35 to 44 years then switching to five-yearly colonoscopy from age 45 to 74 years.
Screening recommendations for individuals at near average and moderately increased risk also include earlier screening than age 50 as per the National Bowel Cancer Screening Program (NBCSP) for the general population.
iFOBT from age 45 years should be considered in individuals at slightly increased risk – those with one first-degree relative with colorectal cancer diagnosed at 55 years or older.
In people with moderately increased risk, for example those with one first-degree relative with colorectal cancer diagnosed with colorectal cancer before age 55 years, biennial iFOBT is recommended from age 40 to 49 years then five-yearly colonoscopy from age 50 to 74 years.
Professor Jenkins said the guidelines relied upon clinicians initiating discussions about bowel cancer screening and family history then prescribing iFOBT if patients were younger than 50 years and therefore not yet eligible for the NBCSP.
The MJA article said the optimal age to stop screening was not known.
“Health economic research is needed to determine whether the benefits of iFOBT screening or colonoscopy screening beyond age 74 years outweigh the inherent risks.”
“Health economic research within varying national cost contexts is needed to assess the cost-effectiveness of screening for various categories of family history, evaluate the screening strategies and further examine the relationship between risk and age.”