Research Studies

California Teachers Study


California Teachers Study website:  http://www.calteachersstudy.org

The California Teachers Study (CTS) is a long-term, follow-up (prospective cohort) study of 133,479 female teachers and school administrators. In 1995 and 1996, participants completed an extensive questionnaire that focused on lifestyle, medical history, and women's health. Each year, cohort members receive a newsletter, and every other year, they provide the CTS researchers with updated or new information about their health and lifestyle. Cancer diagnoses are confirmed through the statewide California Cancer Registry (www.ccrcal.org). 

The CTS is a collaborative study conducted by the University of Southern California (USC), the Northern California Cancer Center, the University of California at Irvine (UCI), and the California Cancer Registry (CCR). 

Read recent news article on the CTS

There are many components to the CTS. The following briefly describes those in which the NCCC is involved:

Emergent Hypotheses Regarding the Causes of Breast and Other Cancers
The main focus of the CTS is the evaluation of a wide range of emergent hypotheses related to the development of breast and other cancers. NCCC researchers are investigating the influence of obesity, diet, alcohol, and other environmental exposures such as tobacco smoke, pesticides, and air pollution. The researchers at other institutions are looking at factors such as physical activity, hormone replacement therapy, and heredity.

Some of our findings to date:  

• Teachers develop breast, endometrial, ovarian and thyroid cancer, melanoma, lymphoma, and leukemia more often than comparable women in California. Teachers, however, develop less cervical and lung cancer.  These observations have helped us focus our efforts on trying to understand the causes and prevention of cancer in women.
  
• Drinking two or more alcoholic beverages a day increases a woman's risk of breast cancer. One drink per day - which helps reduce the risk of heart disease - does NOT increase breast cancer risk. Current drinking is more important than past drinking. The combination of alcohol consumption (of 2+ drinks per day) and use of hormone replacement therapy was associated with the greatest breast cancer risk.
  
• Other than drinking alcohol, there are no overall associations between dietary intake and breast cancer risk. Greater intake of isoflavones (the primary phytoestrogens found in soy-based foods), however, was associated with a reduced risk of ovarian cancer.

Current research is expanding on these findings by looking at the influence of normal genetic variation in metabolism on the relationship between alcohol and breast cancer risk; the relationship between alcohol and mortality; and whether diet affects specific types of breast cancer such as ER+/PR+ or ER-/PR-. We are also investigating whether compounds found in particular plant foods (e.g., the isothiocyanates found in cruciferous vegetables such as broccoli and cauliflower) may reduce the risk of developing breast, endometrial, and thyroid cancer in some women.  Also under current study are the effects of foods that impact insulin-levels on endometrial and thyroid cancer risk. 

Dietary Patterns and Cancer Risk
One of our interests is how overall dietary patterns may impact cancer risk. We have identified five major dietary patterns among cohort members: "plant-based," "high-protein/high-fat," "high-carbohydrate," "ethnic," and "salad-and-wine" and are currently evaluating how these patterns influence the risk of breast and ovarian cancers.

Special Nutrition Assessment Project (SNAP)
The Special Nutrition Assessment Project (SNAP) collected detailed dietary and environmental exposure information on a sample of 320 cohort members. This information was used to (1) better understand and sharpen our measures of dietary intake for the entire cohort, and (2) evaluate differences in environmental exposures for residents of urban areas as compared to residents of rural areas (as a group, residents of rural areas experience lower breast cancer rates).

Body Size and Cancer Risk
We are in the process of using data on height, weight, and waist and hip circumferences to evaluate how various aspects of body size (including overall and abdominal obesity and weight gain during different periods of life) impact the development of breast, endometrial, ovarian, and thyroid cancers, and whether factors, such as the use of hormone replacement therapy, modify these relationships.

Obesity and Asthma
There has been recent interest in the association between obesity and asthma, particularly in women. We are currently assessing the relationship between indicators of body size, including body mass index, waist circumference, waist-to-hip ratio, waist-to-height ratio and weight gain, and asthma prevalence and severity in the CTS. Because of the large size of the cohort, this study offers the opportunity to assess these relationships in greater detail than has been possible in previous studies.

Regional Differences in Breast Cancer Incidence Rates
We have used data from the cohort combined with ecological, environmental databases to evaluate the factors that might be responsible for the urban-rural (and other geographic) differences in breast cancer incidence rates. We found that as reported in other areas, breast cancer rates among cohort participants are higher in urban areas (the San Francisco Bay Area and the Southern Coastal region) than in other (largely rural) areas of the state. Socioeconomic and personal risk factors (e.g., alcohol consumption, use of hormone replacement therapy, delayed childbearing, etc.) do not account for more than a small portion of these geographic differences.

Second Hand Smoke
We have evaluated the role of lifetime exposure to second hand smoke (SHS; i.e., "passive smoking") on the development of breast cancer. In initial analyses limited to household exposures, we found that while current smoking increases the risk of breast cancer, exposure to household SHS does not. We are currently assessing the role of SHS on breast cancer based on follow-up information collected on lifetime SHS exposures from a broader range of sources, including workplace and social settings.

Air Pollution and Cardiopulmonary Mortality
Working with colleagues at the California Department of Public Health and the California Environmental Protection Agency, we are utilizing our Geographic Information System and specialized air monitoring data generated by the California Air Resources Board to assess the contribution of targeted air pollutants on cardiopulmonary mortality in women enrolled in the CTS. Because of the geographic diversity of CTS members in California and the extensive air monitoring information available, findings from this study can have an important impact on regulatory standards in the State.

Built Environment and Breast Cancer Risk
The built environment refers to man-made attributes of a person's surroundings, such as the existence and condition of sidewalks, availability of resources (health care, food, playgrounds, public transportation) and the number of destinations in walking distance. We are currently conducting the first study to examine whether characteristics of the built environment affect the risk of developing breast cancer. 

Nutrition, Estrogens and Endometrial Cancer in Teachers (NEET)
This special study is investigating  how normal genetic variation in the metabolism of female hormones impacts the relationship between endometrial cancer and its two major risk factors -- obesity and use of estrogen hormone therapy. In addition, we are evaluating how phytoestrogens may reduce the risk of endometrial cancer.  

Collaborators
NCCC: Pamela L. Horn-Ross, Ph.D., Peggy Reynolds, Ph.D., Dee W. West, Ph.D., Christina A. Clarke, Ph.D., Ellen T. Chang, Ph.D., Theresa H.M. Keegan, Ph.D.
USC: Leslie Bernstein, Ph.D., Dennis Deapen, Dr.P.H., Giske Ursin, M.D., Daniel O. Stram, Ph.D.
UCI: Hoda Anton-Culver, Ph.D., Al Ziogas, Ph.D., Susan Neuhausen, Ph.D.
CCR: Rosemary Cress, Ph.D.

Funding: National Cancer Institute (R01 CA77398, R01 CA91019, U01 CA81789, R03 CA 125819, and R03 CA13024), California Breast Cancer Research Program (4JB-0116 and 6JB-0111), California Breast Cancer Research Fund (97-10500), California Tobacco Related Diseases Research Program (7TR-0142 and 13RT-0018), and The Carl Gellert and Celia Berta Gellert Foundation.

Publications:
Bernstein L, Allen M, Anton-Culver H, Deapen D, Horn-Ross PL, Peel D, Pinder R, Reynolds P, Sullivan-Halley J, West D, Wright W, Ziogas A, Ross RK. High breast cancer incidence rates among California teachers: results from the California Teachers Study. Cancer Causes Control 2002; 13:625-635.

Horn-Ross PL, Hoggatt KJ, West DW, Krone MR, Stewart SL, Anton H, Bernstein CL, Deapen D, Peel D, Pinder R, Reynolds P, Ross RK, Wright W, Ziogas A. Recent diet and breast cancer risk: the California Teachers Study. Cancer Causes and Control 2002; 13:407-415.

Hoggatt KJ, Bernstein L, Reynolds P, Anton-Culver H, Deapen D, Peel D, Pinder R, Ross RK, West DW, Wright W, Ziogas A, Horn-Ross PL. Correlates of vitamin supplement use in the California Teachers Study cohort. Cancer Causes Control 2002; 13:735-740.

Marshall SF, Deapen D, Allen M, Anton-Culver H, Bernstein L, Horn-Ross PL, Peel D, Pinder R, Reynolds P, Ross RK, West D, Ziogas A. Validating California Teachers Study self-reports of recent hospitalization: comparison with California hospital discharge data. Am J Epidemiol 2003; 158:1012-1020.

Parikh-Patel A, Allen MA, Wright WE. The California Teachers Study Steering Committee.  Validation of self-reported cancers in the California Teachers Study.  Am J Epidemiol 2003; 157:539-545.

Reynolds P, Goldberg DE, Hurley S, and the California Teachers Study Investigators. Prevalence and patterns of ETS exposures among California teachers. Am J Hlth Promotion 2004; 18:358-365.

Reynolds R, Hurley S, Goldberg DE, Anton-Culver H, Bernstein L, Deapen D, Horn-Ross PL, Peel D, Pinder R, Ross RK, West D, Wright WE, Ziogas A. Active smoking, household passive smoking, and breast cancer: evidence from the California Teachers Study. J Natl Cancer Inst 2004; 96(1):29-37.

Horn-Ross PL, Canchola AJ, West DW, Stewart SL, Bernstein L, Deapen D, Pinder R, Ross RK, Anton-Culver H, Peel D, Ziogas A, Reynolds P, Wright W. Patterns of alcohol consumption and breast cancer risk in the California Teachers Study Cohort. Cancer Epidemiol Biomarker Prev 2004; 13:405-411.

Reynolds P, Hurley SE, Goldberg DE, Yerabati S, Gunier RB, Hertz A, Anton-Culver H, Bernstein L, Deapen D, Horn-Ross PL, Peel D, Pinder R, Ross RK, West D, Wright WE, Ziogas A. Residential proximity to agricultural pesticide use and incidence of breast cancer in the California Teachers Study cohort. Environ Res 2004; 96:206-218.

Reynolds P, Hurley S, Goldberg DE, Anton-Culver H, Bernstein L, Deapen D, Horn-Ross PL, Peel D, Pinder, Ross RK, West DW, Wright WE, Ziogas A. Regional variations in breast cancer incidence in the California Teachers Study cohort. Epidemiology 2004; 15:746-754.

Reynolds P, Hurley S, Hoggatt KJ, Anton-Culver H, Bernstein L, Deapen D, Peel D, Pinder R, Ross RK, West D, Wright W, Ziogas A, Horn-Ross PL.  Correlates of active and passive smoking in the California Teachers Study cohort. J Women's Health 2004; 13:778-790.

Hurley SE, Reynolds P, Goldberg DE, Hertz A, Anton-Culver H, Bernstein L, Deapen D, Peel D, Pinder R, Ross RK, West D, Wright WE, Ziogas A, Horn-Ross PL.  Residential mobility in the California Teachers Study:  implications for geographic differences in disease rates. Social Sci Med 2005; 60:1547-1555.

Marshall SF, Bernstein L, Anton-Culver H, Deapen D, Horn-Ross PL, Peel D, Pinder R, Purdie D, Reynolds P, Stram D, West D, Wright WE, Ziogas A, Ross RK.  Non-steroidal anti-inflammatory drug use and breast cancer risk by stage and hormone-receptor status. J Natl Cancer Inst 2005; 97:805-812.

Horn-Ross PL, Barnes S, Lee VS, Collins CN, Reynolds P, Lee MM, Stewart SL, Canchola AJ, Wilson L, Jones K.  Reliability and validity of an assessment of usual phytoestrogen consumption. Cancer Causes Control 2006; 17:85-93.

Smith-Warner SA, Spiegelman D, Ritz J, Albanes D, Beeson WL, Bernstein L, Berrino F, van den Brandt PA, Buring JE, Cho E, Colditz GA, Folsom AR, Freudenheim JL, Giovannucci E, Goldbohm RA, Graham S, Harnack L, Horn-Ross PL, Krogh V, Leitzmann MF, McCullough ML, Miller AB, Rodriguez C, Rohan TE, Schatzkin A, Shore R, Virtanen M, Willett WC, Wolk A, Zeleniuch-Jacquotte A, Zhang SM, Hunter DJ.  Methods for pooling of results of epidemiologic studies:  the pooling project of prospective studies of diet and cancer. Am J Epidemiol 2006; 163:1054-1063.

Gunier RB, Reynolds P, Hurley SE, Yerabati S, Hertz A, Strickland P, Horn-Ross, PL.   Estimating exposure to polycyclic aromatic hydrocarbons: a comparison of survey, biological monitoring, and Geographic Information System-based methods. Cancer Epidemiol Biomarker Prev 2006; 15:1376-1381.

Chang ET, Lee VS, Canchola AJ, Clarke CA, Purdie DM, Anton-Culver H, Bernstein L, Cress R, Deapen D, Peel D, Pinder R, Reynolds P, Ross RK, Stram DO, West DW, Wright W, Ziogas A, Horn-Ross PL.  Dietary intake and risk of ovarian cancer in the California Teachers Study cohort. Am J Epidemiol 2007; 165:802-813.

Chang ET, Canchola AJ, Lee VS, Clarke CA, Purdie DM, Reynolds P, Anton-Culver H, Bernstein L, Deapen D, Mohrenweiser H, Peel D, Pinder R, Stram DO, Ross RK, West DW, Wright W, Ziogas A, Horn-Ross PL.  Wine and other alcohol consumption and risk of ovarian cancer in the California Teachers Study cohort. Cancer Causes Control 2007; 18:91-103.

Dallal CM, Sullivan-Halley J, Ross RK, Wang Y, Deapen D, Horn-Ross PL, Reynolds P, Stram DO, Pinder R, Clarke CA, Anton-Culver H, Ziogas A, Peel D, West DW, Wright W, Bernstein L.  Long-term recreational physical activity and risk of invasive and in situ breast cancer: the California Teachers Study. Arch Internal Med 2007; 167:408-415.

Mai PL, Sullivan-Halley J, Ursin G, Stram DO, Deapen D, Villaluna D, Horn-Ross PL, Clark CA, Reynolds P, Ross RK, West DW, Anton-Culver A, Ziogas A, Bernstein L.  Physical activity and colon cancer risk among users and non-users of hormone therapy:  the California Teachers Study. Cancer Epidemiol Biomarker Prev 2007; 16:517-525.

Lee JE, Hunter DJ, Spiegelman D, Adami H-O, Albanes D, Bernstein L, van den Brandt PA, Buring JE, Cho E, Folsom AR, Freudenheim JL, Giovannucci E, Graham S, Horn-Ross PL, Leitzmann MF, McCullough ML, Miller AB, Parker AS, Rodriguez C, Rohan TE, Schatzkin A, Schouten LJ, Virtanen M, Willett WC, Wolk A, Zhang SM, Smith-Warner SA.  Alcohol intake and renal cell cancer in a pooled analysis of 12 prospective studies. J Nat'l Cancer Inst 2007; 99:801-810.

Lee JE, Hunter DJ, Spiegelman D, Adami H-O, Bernstein L, van den Brandt PA, Buring JE, Cho E, Folsom AR, Freudenheim JL, Giles GG, Giovannucci E, Horn-Ross PL, Leitzmann M, Marshall JR, Männistö S, McCullough ML, Miller AB, Parker AS, Pietinen P, Rodriguez C, Rohan TE, Schatzkin A, Schouten LJ, Willet WC, Wolk A, Zhang SM, Smith-Warner SA.  Intakes of coffee, tea, milk, soda, and juice and renal cell cancer in a pooled analysis of 13 prospective studies. Int J Cancer, in press.

Templeman C, Marshall SF, Ursin G, Horn-Ross PL, Clarke CA, Allen, M, Deapen D, Ziogas A, Reynolds P, Cress R, Anton-Culver H, West DW, Ross RK, Bernstein L.  Adenomyosis and endometriosis in the California Teachers Study:  reproductive and lifestyle correlates. Fertil Steril, in press.

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