Colorectal cancer in hereditary breast cancer kindreds

PURPOSE: This study compared characteristics of colorectal cancer between f amilies with dominant breast cancer inheritance and the general population. The cumulative incidence of colorectal cancer was also studied in genetica lly determined breast cancer syndrome subjects with BRCA1 and BRCA2 mutatio ns and compared with the general population. METHODS: Subjects included 42 patients with colorectal cancer from 32 clinically determined hereditary br east cancer kindreds based on the autosomal dominant inheritance of breast cancers and early age of onset. The general population colorectal cancer co hort was composed of 755 patients from a tumor registry. Lifetime risk of c olorectal cancer was determined in 164 BRCA1 and 88 BRCA2 gene mutation car riers and compared with the general population. Mean age of colorectal canc er onset, anatomic site distribution, histologic stage at presentation, and five year stage-stratified survival rates were compared between clinically determined hereditary breast cancer family members and the general populat ion. RESULTS: The lifetime risk of colorectal cancer in male BRCA1 and BRCA 2 mutation carriers was 5.6 percent, which was not different from 6 percent in males from the general population. Likewise, the lifetime colorectal ca ncer risk in female BRCA1 and BRCA2 mutation carriers was 3.2 percent, whic h was not different from 5.9 percent in females from the general population . Mean age of onset +/- standard error for patients with colorectal cancer was 60 +/- 2 years for hereditary breast cancer kindreds compared with 67 /- 0.4 years for the general population (P = 0.0004). Colorectal cancer sit e distribution did not vary between hereditary breast cancer and the genera l population. Overall colorectal cancer stage distribution was significantl y different, with more Stage I and fewer Stage IV cancers in subjects with hereditary breast cancer compared with the general population (P = 0.01). O verall five year stage-stratified colorectal cancer survival rate +/- stand ard error was 66 +/- 8 percent for hereditary breast cancer kindreds and 46 +/- 2 percent for the general population (P = 0.023). CONCLUSION: Lifetime cumulative colorectal cancer incidence in subjects with BRCA1 and BRCA2 ge ne mutations was not different from the general population. However, signif icant differences in colorectal cancer were noted between hereditary breast cancer family members and the general population. Hereditary breast cancer -associated colorectal cancer had an earlier age of onset, lower tumor stag e, and better survival tate than the general population. Except for age of onset, colorectal cancer in hereditary breast cancer kindreds exhibited mor e favorable characteristics than colorectal cancer in the general populatio n.