Family history of cancer in children and young adults with colorectal cancer

Background, Family history of colorectal cancer among adult patients has be en reported in the literature. Although extremely rare in children, colorec tal cancer in this population may represent a unique group in whom genetic factors play a significant etiologic role. The aim of the present study was to assess genetic contribution, as measured by family history, to the deve lopment of colorectal cancer in probands under 21 years of age at diagnosis . Procedure. Detailed family histories were obtained from surviving patient s or their parents. The risk [standardized incidence ratio (SIR)] of cancer in the relatives was calculated by comparing the observed and the expected incidence based on rates in the general population and person-years at ris k. Results, Twenty-five patients (median age at diagnosis 15 years) diagnos ed with colorectal cancer at St. Jude Children's Research Center since 1964 or their surviving next of kin were available for interview. The 461 relat ives contributed 18;908 person-years of follow-up. Statistically significan t increased risk of colorectal cancer was present among all relatives (SIR = 6.0, 95% CI, 2.7-10.6), and the increased risk of colorectal cancer was c on; fined to relatives of probands who were under 15 years of age at diagno sis (SIR = 10.0, 95% CI, 4.5-17.6). In addition, there was an excess of ute rine/cervical cancer among all female relatives (SIR = 6.5, 95% CI, 3.2-10. 9). Conclusions,The observed excess of colorectal cancer, in relatives of y ounger probands, suggests the need to examine these kindreds for genetic in stability resulting from defects in mismatch repair genes to characterize f urther the patterns of risk observed. (C) 1999 Wiley-Liss, Inc.