Accuracy of family history of cancer: clinical genetic implications

Family medical history is the cornerstone of clinical genetic diagnosis and management in cases of familial cancer. The soundness of medical decisions can be compromised if reports by the family on affected relatives are inac curate. Although very time consuming, family medical histories are therefor e routinely verified. To investigate whether such verification is clinicall y justified, we retrospectively analysed the accuracy of a consecutive seri es of 383 tumour reports from counsellees on 120 families in our clinic. We evaluated these families for the impact of verification on clinical geneti c diagnosis and management. Accuracy according to cancer type showed marked variation, ranging from 93% and 89% for breast cancer and colorectal cance r, respectively, to 42% and 37% for extra-colorectal alimentary tract cance r and uterine cancer. Accuracy was related to the degree of kinship of the affected relative, but not to age and gender of the counsellee, nor to the reason for referral or personal history of cancer. Age at diagnosis and mul tiple primary tumours were reported accurately in 97% and 94% of cases, res pectively. In six out of 120 families verification data changed clinical ge netic management, in five of these the genetic risk was reduced. Although v erification of all reported cancer cases in a family remains the 'gold stan dard' for clinical as well as research purposes, verification of reports on breast cancer can be limited without seriously compromising medical decisi on making. In cases where verification is impossible because medical record s are unavailable, findings from studies such as ours may help in interpret ing family histories.