Family history of prostate and colorectal cancer and risk of colorectal cancer in the Women\u2019s health initiative

Michael S. Simon,Cathryn H. Bock,Ann G. Schwartz,Rami Nassir,Dorothy Lane,Electra Paskett,Cecilia Yee,Jennifer L. Beebe-Dimmer,Nynikka R. A. Palmer

doi:10.1186/s12885-017-3873-5

Abstract

BackgroundEvidence suggests that risk of colorectal and prostate cancer is increased among those with a family history of the same disease, particularly among first-degree relatives. However, the aggregation of colorectal and prostate cancer within families has not been well investigated.MethodsAnalyses were conducted among participants of the Women’s Health Initiative (WHI) observational cohort, free of cancer at the baseline examination. Subjects were followed for colorectal cancer through August 31st, 2009. A Cox-proportional hazards regression modeling approach was used to estimate risk of colorectal cancer associated with a family history of prostate cancer, colorectal cancer and both cancers among first-degree relatives of all participants and stratified by race (African American vs. White).ResultsOf 75,999 eligible participants, there were 1122 colorectal cancer cases diagnosed over the study period. A family history of prostate cancer alone was not associated with an increase in colorectal cancer risk after adjustment for confounders (aHR =0.94; 95% CI =0.76, 1.15). Separate analysis examining the joint impact, a family history of both colorectal and prostate cancer was associated with an almost 50% increase in colorectal cancer risk (aHR = 1.48; 95% CI = 1.04, 2.10), but similar to those with a family history of colorectal cancer only (95% CI = 1.31; 95% CI = 1.11, 1.54).ConclusionsOur findings suggest risk of colorectal cancer is increased similarly among women with colorectal cancer only and among those with both colorectal and prostate cancer diagnosed among first-degree family members. Future studies are needed to determine the relative contribution of genes and shared environment to the risk of both cancers.

Highlights

Evidence suggests that risk of colorectal and prostate cancer is increased among those with a family history of the same disease, among first-degree relatives
The current study evaluates the impact of a family history of prostate cancer and aggregation of prostate and colorectal cancer among first-degree relatives on risk of colorectal cancer in the Women’s Health Initiative Observational Study (WHI OS)
We identified 1122 incident colorectal cancer cases during follow-up of participants with a median number of years of follow-up in the cohort of 14.6 years (InterQuartile Range = 8.5, 16.2) These cases were older at time of baseline survey, and were more likely than non-cases to be non-Hispanic white (85.0% v. 83.2%; p = 0.008), obese (28.6% v. 24.2%; p < 0.0001), have a greater waist circumference (p < 0.0001), a history of smoking (50.9% v. 47.8%; p = 0.04), and diabetes (7.6% v. 5.3%; 0.0008)

Summary

Introduction

Evidence suggests that risk of colorectal and prostate cancer is increased among those with a family history of the same disease, among first-degree relatives. The aggregation of colorectal and prostate cancer within families has not been well investigated. Very few genes have been consistently reported in familial and hereditary prostate cancer apart from BRCA 1 and BRCA2 as well as HOXB13 [16,17,18,19]. Aggregation of colorectal and prostate cancer within families has not been as thoroughly investigated. The aggregation of colorectal and prostate cancer within families is likely due to a combination of both genes and shared environment, with environmental exposures occurring earlier in life perhaps more important. African American men are approximately 60% more likely to be diagnosed with prostate cancer and 2.5 times more likely to die compared to white men [27]

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Conclusion