High breast cancer incidence rates among California teachers: results from the California Teachers Study (United States).
OBJECTIVE
[corrected] To determine risk factor profiles and cancer incidence rates among participants in the California Teachers Study (CTS), a study designed to document high breast cancer incidence rates of California teachers and to investigate emergent hypotheses in the etiology of breast and other cancers.


METHODS
The CTS is a prospective study of 133,479 California female teachers and administrators, established in 1995-1996 with members of the California State Teachers Retirement System completing a detailed mailed questionnaire regarding possible risk factors for breast and other cancers. Cancer outcomes were identified by linkage with the California Cancer Registry.


RESULTS
CTS participants have a 51% higher age-standardized invasive breast cancer incidence rate and a 67% higher in-situ breast cancer incidence rate than would be expected based on race-specific statewide rates after three years of follow-up. CTS participants also have substantially elevated rates of endometrial cancer (rate ratio, RR = 1.72), ovarian cancer (RR = 1.28), melanoma (RR = 1.59), non-Hodgkin's lymphoma (RR= 1.53), and leukemia (RR = 1.28), but low rates of invasive cervix cancer (RR = 0.53) and lung cancer (RR = 0.66).


CONCLUSIONS
CTS members have high rates of several major cancers, particularly breast cancer, and low rates of lung and cervix cancer. Although late age at first birth can explain a portion of the observed excess risk of breast cancer in this cohort, the unique risk factor profile of CTS members may account for much of their higher risk of breast and selected other cancers. The CTS offers a rich resource for future studies of cancer risk and of women's health, in general.
Bernstein
Leslie
L
Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles 90033, USA. lbern@hsc.usc.edu
Allen
Mark
M
Anton-Culver
Hoda
H
Deapen
Dennis
D
Horn-Ross
Pamela L
PL
Peel
David
D
Pinder
Richard
R
Reynolds
Peggy
P
Sullivan-Halley
Jane
J
West
Dee
D
Wright
William
W
Ziogas
Al
A
Ross
Ronald K
RK
D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000473:pathology*; D002140:California / Q000453:epidemiology; D005260:Female; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009367:Neoplasm Staging; D009790:Occupations; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D016019:Survival Analysis; D013663:Teaching