BACKGROUND: Relatives of patients with bowel neoplasia have an increased risk of bowel neoplasia. If there were concordance in location of neoplasia between relatives, then location-specific screening could be used. Such concordance might also assist in the understanding of the etiology of neoplasia within individual families. METHODS: We have investigated the concordance in anatomic location of colonic neoplasia between first-degree relatives using a new statistical technique for paired data called alternating logistic regression. RESULTS: A total of 146 families were ascertained, none of which had clinical evidence of a hereditary predisposition to edon neoplasia. Among those with neoplasia, there was an increased risk for right-sided disease with older age (40% for less than age 60 vs. 58% for at least 70 years of age, p = 0.008). As assessed by the odds ratio, we found no significant concordance within families for location of neoplasia (odds ratio = 1.2: CI [0.7, 2.2]), although there was a suggestion that location in family members of the same generation was more strongly associated (odds ratio 1.87: CI [0.82, 4.25]). CONCLUSIONS: The lack of concordance within families for location argues against considering family-specific bowel screening protocols and indicates that the most important causes of bowel neoplasia are not sufficiently focused on one anatomic site to facilitate etiologic research.
BACKGROUND: Relatives of patients with bowel neoplasia have an increased risk of bowel neoplasia. If there were concordance in location of neoplasia between relatives, then location-specific screening could be used. Such concordance might also assist in the understanding of the etiology of neoplasia within individual families. METHODS: We have investigated the concordance in anatomic location of colonic neoplasia between first-degree relatives using a new statistical technique for paired data called alternating logistic regression. RESULTS: A total of 146 families were ascertained, none of which had clinical evidence of a hereditary predisposition to edon neoplasia. Among those with neoplasia, there was an increased risk for right-sided disease with older age (40% for less than age 60 vs. 58% for at least 70 years of age, p = 0.008). As assessed by the odds ratio, we found no significant concordance within families for location of neoplasia (odds ratio = 1.2: CI [0.7, 2.2]), although there was a suggestion that location in family members of the same generation was more strongly associated (odds ratio 1.87: CI [0.82, 4.25]). CONCLUSIONS: The lack of concordance within families for location argues against considering family-specific bowel screening protocols and indicates that the most important causes of bowel neoplasia are not sufficiently focused on one anatomic site to facilitate etiologic research.