Risk factors for colorectal cancer following breast cancer.
OBJECTIVE
To investigate risk factors for colorectal cancer following breast cancer.


METHODS
In this nested case-control study, all women (n = 14,900) with a first primary breast cancer (1978-1992) were identified from the western Washington population-based Surveillance, Epidemiology, and End Results Cancer Registry. Cases (n = 160) developed a second primary colorectal cancer before 1995, at least 6 months after the first cancer diagnosis. Controls (n = 310, matched to the cases on calendar year, age and breast cancer stage) were randomly selected from those who did not develop a second primary cancer and who survived to the case's colorectal cancer diagnosis date. Characteristics of the cases and controls at initial diagnosis were compared using conditional logistic regression.


RESULTS
The incidence of colorectal cancer was associated with a family history of breast cancer (v.s. no family history, matched odds ratio (mOR) = 2.1, 95% confidence interval (CI): 1.1-4.1), high body mass index (> or = 30kg/m2 v.s. < 30kg/m2, mOR = 2.2, CI: 1.2-3.9), and lobular breast cancer histology (v.s. ductal, mOR = 2.0, CI: 0.9-4.4). Risk was unrelated to menopausal status, prior hormone replacement therapy and estrogen/progesterone receptor status of the breast tumors.


CONCLUSIONS
The risk of developing a second primary colorectal cancer may be elevated among certain subsets of breast cancer patients.
Kmet
Leanne M
LM
Department of Community Health Sciences, University of Calgary, Alta., Canada.
Cook
Linda S
LS
Weiss
Noel S
NS
Schwartz
Stephen M
SM
White
Emily
E
D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000453:epidemiology*; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000235:genetics; D015897:Comorbidity; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008875:Middle Aged; D018299:Neoplasms, Ductal, Lobular, and Medullary / Q000453:epidemiology; D016609:Neoplasms, Second Primary / Q000453:epidemiology*; D016017:Odds Ratio; D011159:Population Surveillance; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D014861:Washington / Q000453:epidemiology