Confirming a diagnosis of hereditary colorectal cancer: the impact of a Familial Bowel Cancer Registry in New Zealand.

AIMS

The optimal management of familial bowel cancer is thought to involve specialised familial cancer units and registries that facilitate a multidisciplinary approach. We studied the impact this approach had on the investigation and management of affected families in our register.

METHOD

A review of the outcomes of assessment for 25 families was undertaken. These families have completed assessment by the Northern Regional Genetic Service Familial Bowel Cancer Registry because of the possibility of a hereditary bowel cancer syndrome. Details of the cancer history and screening advice known at the time of initial referral to the genetic service, and at the end of assessment, were compared.

RESULTS

Detailed family history revealed 130 cancers, 90 of which were known at referral. Eighty-four cancers were confirmed, of which 73 belonged to the spectrum of cancers associated with hereditary nonpolyposis colorectal cancer (HNPCC). The mean age of diagnosis was 56.3 years. Eight families met the modified Amsterdam Criteria for the diagnosis of HNPCC, compared to four families at the time of referral. Familial hyperplastic polyposis was diagnosed in one family. 164 asymptomatic at-risk first-degree relatives were identified, 48 from families who met the Amsterdam criteria and were thereby recommended to have intensive colonoscopic screening.

CONCLUSION

Assessment by the Familial Bowel Cancer Registry increased the number of cancers identified in families, thus facilitating a diagnosis of HNPCC in a third of the referred families and a diagnosis of hyperplastic polyposis in one other. Consequently specialised genetic testing and intensive colonoscopic surveillance could be targeted to the asymptomatic first-degree relatives most at risk. Ongoing coordination of colonoscopic surveillance by the registry for those individuals identified to have disease causing mutations or to be at-risk, is anticipated to reduce the number of deaths from colorectal cancer in these families.