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Brief Description of the Pooling Project and Component Studies

Pooling Project
The Pooling Project of Prospective Studies of Diet and Cancer (Pooling Project) is an international consortium of cohort studies with the goal of analyzing diet and cancer associations using standardized criteria across studies. This project is an example of a meta-analysis of individual data as opposed to a meta-analysis of the published literature. The studies in the Pooling Project were initiated independently and have either completed follow-up of their participants or are ongoing.

The purposes of the Pooling Project are multi-fold. We evaluate whether diet and cancer associations are consistent across cohort studies comprised of different populations with different dietary habits. For each association, we generate summary estimates which have greater precision than any of the individual studies due to the larger sample size. We also examine whether associations differ for specific population subgroups (ex: between men and women; among never, past and current smokers; between lean and overweight individuals) or for different histologic types or subsites of specific cancers.

To maximize the quality and comparability of the studies in the Pooling Project, we formulated several inclusion criteria a priori. Each study is a published cohort study which 1) used a comprehensive dietary assessment method to measure usual diet, 2) assessed the validity of their dietary assessment instrument or a closely related instrument, and 3) included a minimum number of cases of the specific cancer being examined. Additional inclusion criteria also have been made for specific cancers. Currently, 28 studies are included in the Pooling Project. However, as we become aware of new studies meeting the inclusion criteria, those studies are invited to join the Pooling Project.

A brief description of each cohort study included in the Pooling Project is given below.

The Adventist Health Study, AHS
The Adventist Health Study was assembled in 1976 when 13,857 male and 20,341 female California Seventh-day Adventists aged 25 years and older completed a detailed lifestyle questionnaire. The participants for this cohort were identified from a census questionnaire that was mailed to all Seventh-day Adventist households in California in 1974. Participants in the study were followed for cancer incidence though 1982.

Alpha-Tocopherol Beta-Carotene Prevention Study, ATBC
The Alpha-Tocopherol Beta-Carotene Prevention Study is a randomized, double-blind, placebo-controlled clinical trial that was designed to evaluate whether daily supplements of alpha-tocopherol and/or beta-carotene would reduce the risk of lung cancer and other types of cancer. The study consists of 29,133 male smokers who resided in southwestern Finland and were 50-69 years at enrollment in 1985-1988.

The NIH-AARP Diet and Health Study, AARP
The NIH-AARP Diet and Health Study was initiated in 1995 to study relationships between diet and cancer. The study population consisted of 340,148 men and 227,021 women, who were members of the American Association of Retired Persons in 6 states and 2 metropolitan areas in the U.S., and were aged 50 to 71 years at the begiinning of the study. Participants completed a mailed questionnaire that included the diet history, demographic characteristics and other potential cancer risk factors.

Beta-Carotene and Retinol Efficacy Trial, CARET
The Beta-Carotene and Retinol Efficacy Trial was a multicenter randomized, double-blind placebo controlled chemoprevention trial that tested whether daily supplementation with 30 mg beta-carotene plus 25,000 IU retinyl palmitate would reduce lung cancer incidence in a high risk population. The trial was conducted among 18,314 heavy smokers, former heavy smokers and persons with occupational exposure to asbestos. All participants completed a food frequency questionnaire at baseline and every two years thereafter.

The Black Women's Health Study, BWHS
The Black Women's Health Study is the largest medical study of African-American women to date. This ongoing study was designed to examine risk factors for cancer and other serious illnesses in African-American women. The cohort was established in 1995 when 59,000 black women between the ages of 21 and 69 years completed mailed questionnaires. The baseline questionnaire collected information on demographic factors, medical and reproductive history, use of oral contraceptives and other medications, physical activity, smoking, alcohol, diet, and other factors.

Breast Cancer Detection Demonstration Project Follow-up Cohort, BCDDP
The Breast Cancer Detection Demonstration Project Follow-up Cohort consists of a subset of participants (n = 64182) who had participated in a national mammography screening program conducted from 1973-1981 at 29 U.S. centers (total number who participated in the screening program was 283,222). The dietary component of the study began in 1987-1989 when 54,442 participants completed a self-administered food frequency questionnaire. Follow-up for cancer incidence is ongoing.

California Teachers Study, CTS
The California Teachers Study (CTS), started in 1995, is an ongoing prospective study of 133,479 current and former public school teachers and other school professionals who participate in the California State Teachers Retirement System (STRS). The baseline questionnaire focused on potential breast cancer risk factors including a comprehensive assessment of diet, alcohol use, use of hormone therapy and oral contraceptives, physical activity, menstrual and reproductive factors, family history of cancer and other diseases, exposure to electromagnetic fields, and smoking.

Campaign Against Cancer and Heart Disease, CLUE II
In 1989, the Campaign against Cancer and Stroke (CLUE II) was conducted in Washington County, MD. Using mobile trailers, the study was designed to collect blood samples from as many adults as possible to provide specimens for a serum bank. A brief medical history and baseline questionnaire was administered to 32,898 persons at the time of blood collection. About one-third of the adult county population participated with additional participants from surrounding communities. Participants were given a food frequency questionnaire to complete at home and were asked to return it.

Canadian National Breast Screening Study, CNBSS
The Canadian National Breast Screening Study is an ongoing prospective study of 56,837 women living in 12 Canadian cities who had participated in a randomized controlled trial of mammography (n = 89,835 women) and had returned a self-administered food frequency questionnaire. The women were 40-59 years at enrollment between 1982 and 1987.

Cancer Prevention Study II Nutrition Cohort, CPS II Nutrition Cohort
The Cancer Prevention Study II Nutrition Cohort is an ongoing cohort study comprised of a subset of participants in the Cancer Prevention Study II, a cohort study of approximately 1.2 million men and women that began in 1982. The Cancer Prevention Study II Nutrition Cohort consists of 86,406 men and 97,788 women who completed a self-administered questionnaire on diet, lifestyle factors, and medical history in 1992. Participants were 50-74 years old at the beginning of the study.

Cohort of Swedish Men, COSM
The Cohort of Swedish Men began in 1997 when 48,850 men residing in two counties in central Sweden (Västmanland and Örebro) completed a mailed questionnaire. The men were born between 1918 and 1952. They completed a comprehensive questionnaire on lifestyle factors, diet, and medical history.

Health Professionals Follow-up Study, HPFS
The Health Professionals Follow-up Study is an ongoing cohort study that was initiated in 1986 and consists of 51,529 male dentists, pharmacists, optometrists, osteopaths, podiatrists, and veterinarians aged 40-75 years at the beginning of the study.

Iowa Women’s Health Study, IWHS
The Iowa Women’s Health Study is an ongoing prospective study of 41,836 postmenopausal women who were 55-69 years at enrollment in 1986. Participants in the study consist of women initially identified from the 1985 Iowa driver’s license list who completed a mailed self-administered study questionnaire.

The Japan Public Health Center-Based Study Cohort, JPHC
The Japan Public Health Center-Based Study Cohort is an ongoing cohort study that combined Cohort I and II, which began in 1990 and 1993, respectively. The study consists of 45,452 men and 49,924 women who were aged 40 to 69 years at enrollment, and were identified using residence registries maintained by local governments in Japan. Each participant returned self-administered questionnaires that included dietary habits, previous medical history and other lifestyle factors.

Melbourne Collaborative Cohort Study, MCCS
The Melbourne Collaborative Cohort Study is an ongoing cohort study of 24,479 women and 17,049 men aged 27-75 years (99.3% aged 40-69) who resided in Melbourne Australia between 1990 and 1994. Participants were recruited from electoral rolls, advertisements, and community announcements with oversampling of Italian and Greek migrants (30% of participants). Detailed information on lifestyle factors as well as blood samples and direct physical measurements was collected from all participants.

Multiethnic Cohort, MEC
The Multiethnic/Minority Cohort Study was established in Hawaii and Los Angeles in 1993-1996 to explore the relationship of diet and other lifestyle factors to cancer. The cohort is comprised of more than 215,000 men and women primarily of African-American, Japanese, Latino, Native Hawaiian, and Caucasian origin, and is unique among existing cohort studies in its ethnic diversity and representation of minority populations. At entry to the cohort study, each participant completed a 26-page mail questionnaire that included an extensive quantitative diet history, as well as other demographic, medical, and lifestyle information.

The Netherlands Cohort Study, NLCS
The Netherlands Cohort Study on diet and cancer is an ongoing cohort study that was initiated in 1986. The study consists of 58,279 men and 62,573 women who were 55-69 years old at the beginning of the study and were identified from 204 Dutch computerized municipal population registries.

New York State Cohort, NYSC
The New York State Cohort is a prospective study of 32,689 men and 25,279 women that was assembled in 1980 by sending a letter of invitation and questionnaire to all women and a sample of the men in New York State who had the same New York State telephone number for at least 18 years. Participants in this study were followed for cancer incidence though 1987.

New York University Women’s Health Study, NYUWHS
The New York University Women’s Health Study was assembled between 1985 and 1991. It consists of 14,291 women who were 35-65 years at the beginning of the study, attended a breast cancer screening clinic in Manhattan, New York City, and had not used hormonal medications or been pregnant during the previous six months. Follow-up of the participants is ongoing.

The Nurses’ Health Study, NHS
The Nurses’ Health Study is an ongoing cohort study of 121,7000 U.S. female nurses who were residents in 11 large U.S. states and were 30-55 years old at enrollment in 1976. The nutritional component of the Nurses’ Health Study began in 1980; 89,538 women form the diet cohort.

The Nurses’ Health Study II, NHSII
The Nurses's Health Study II is an ongoing cohort study of 116,671 female registered nurses who were aged 25 to 42 years and living in 14 U.S. states at enrollment in 1989. The nutritional component of the Nurses' Health Study began in 1990; 97,809 women form the diet cohort.

Prospective Study on Hormones, Diet and Breast Cancer, ORDET
ORDET is a prospective study of women who were living in Varese Province, northern Italy and were 35-69 years at the beginning of the study. Participants were recruited in 1987-1992 from the general population via radio, television and newspaper advertising and from women attending breast cancer prevention units.

Prostate Cancer Prevention Trial, PCPT
The Prostate Cancer Prevention Trial is a Phase III, randomized, double-blind, placebo-controlled trial of finasteride for the prevention of prostate cancer. A total of 18,882 essentially healthy men, aged 55 and older, were enrolled between 1993 and 1996 at 219 centers in the United States and Canada. The 9,598 men that were randomized to the placebo arm are included in the Pooling Project.

The Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, PLCO
The Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, or PLCO, is a multicenter, two-armed randomized controlled trial that was designed to evaluate whether PSA (men only), digital rectal exam (men only), flexible sigmoidoscopy, chest X-ray, CA-125 blood test (women only), transvaginal ultrasound (women only) screening tests reduce deaths from prostate, lung, colorectal and ovarian cancer. Participants are to be followed for at least 13 years from randomization for cancer and death ascertainment. The trial recruited 154,938 men and women age 55 to 74 years, from 1992-2001.

The Shanghai Women's Health Study, SWHS
The Shanghai Women's Health Study is an ongoing prospective cohort study that was established in 1997-2000. This study consists of 74,942 women who lived in 7 urban communities of Shanghai and completed the baseline interviews at participants' homes.

Swedish Mammography Cohort, SMC
The Sweden Mammography Cohort is an ongoing study of 61,471 women living in two counties in central Sweden who participated in a mammographic screening program between 1987 and 1990. At enrollment, women were 30-74 years old.

The Women’s Health Study, WHS
The Women’s Health Study is an ongoing randomized double-blind, placebo controlled clinical trial of 39,876 female health professionals age 45 years or older. The study, initiated in 1992-1995, used a 2x2x2 factorial design to randomize participants to aspirin or aspirin placebo, vitamin E or vitamin E placebo, and beta-carotene or beta-carotene placebo (this component was terminated in January 1996). Of the women in the trial, 39,345 completed a food frequency questionnaire during the run-in phase prior to randomization.

Women's Lifestyle and Health, WLHS
In 1991 approximately 50,000 women in Sweden aged 30-49 completed a mailed questionnaire. Detailed information was collected on a wide range of lifestyle factors with a focus on oral contraceptive use, diet, UV light exposure, reproductive factors and familial occurrence of cancer.



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