Validation of family history data in cancer family registries.

BACKGROUND: Although family history information on cancer is used to infer risk of the disease in population-based, case-control, cohort, or family-based studies, little information is available on the accuracy of a proband's report. In this study, we sought to determine the validity of the reporting of family history of cancer by probands in population-based and clinic-based family registries of breast, ovarian, and colorectal cancers.
METHODS: To assess the accuracy of probands' reported family history of cancer in their relatives, we compared the family history from the personal interview of each proband to a reference standard that included pathology reports, self-reports, or death certificates on the relatives. Our study included 1111 families that accounted for 3222 relatives who were verified. To account for within-family correlations in the responses, we used a generalized estimating equation approach.
RESULTS: The probability of agreement between the proband-reported cancer status in a relative with the reference standard varied by cancer site and by degree of relationship to the proband. This probability for first-degree relatives was 95.4% (95% confidence interval [CI]=92.6-98.3) for female breast cancer; 83.3% (95% CI=72.8-93.8) for ovarian cancer; 89.7% (95% CI=85.4-94.0) for colorectal cancer; and 79.3% (95% CI=70.0-88.6) for prostate cancer.
CONCLUSIONS: We found high reliability of probands' reporting on most cancer sites when they reported on first-degree relatives and moderate reliability for their reporting on second- and third-degree relatives. Overreporting of cancer was rare (2.4%). Race or ethnicity and gender of the proband did not influence the accuracy of reporting. However, degree of relationship to the proband, type of cancer, age at diagnosis of the proband, and source of ascertainment of probands were statistically significant predictors of accuracy of reporting.