Dr Peter Sasieni and colleagues determined how individuals with family histories of colorectal cancer benefit from colonoscopic surveillance.
The investigative team conducted a prospective, observational study of high risk families, followed up over 16 years.
The team undertook the study in a tertiary referral family cancer clinic in London, England.
There were 1678 individuals from families registered with the clinic.
The team classified individuals were classified according to the strength of their family history.
The classifications included hereditary non-polyposis colorectal cancer, if they fulfilled the Amsterdam criteria, and 1, 2, or 3 affected first degree relatives.
Colonoscopy was initially offered at 5 year intervals or 3 year intervals if an adenoma was detected.
| Individuals with a lesser family history may not require surveillance under age 45|
|British Medical Journal|
The main outcome measure included the incidence of adenomas with high risk pathological features or cancer.
This was analyzed by age, the extent of the family history, and findings on previous colonoscopies.
The cohort was flagged for cancer and death.
The team compared the incidence of colorectal cancer and mortality during over 15,000 person years of follow-up with those expected in the absence of surveillance.
The investigators found that high risk adenomas and cancer were most common in families with hereditary non-polyposis colorectal cancer.
In the families with moderate risk, these findings were particularly uncommon under age 45.
The team also found that these findings were uncommon on follow-up colonoscopy if advanced neoplasia was absent initially.
The incidence of colorectal cancer was substantially lower at 80% in families with moderate risk.
The team noted that the incidence of colorectal cancer was 43% in families with hereditary non-polyposis colorectal cancer.
These results were lower than the expected incidence in the absence of surveillance when the family history was taken into account.
Dr Sasieni's team commented, “Colonoscopic surveillance reduces the risk of colorectal cancer in people with a strong family history.”
“This study confirms that members of families with hereditary non-polyposis colorectal cancer require surveillance with short intervals.”
“Individuals with a lesser family history may not require surveillance under age 45, and if advanced neoplasia is absent on initial colonoscopy, surveillance intervals may be lengthened.”
“This would reduce the demand for colonoscopic surveillance.”