Table 1.

Characteristics of women younger than 55 years in cohorts included in the Premenopausal Breast Cancer Collaborative Group

CohortLocationAges at enrollment; mean (SD), rangeCalendar years of enrollmentBaseline data collection methodsN of data collection roundsaBreast cancer cases (N)Breast cancer ascertainment sourcesCohort size (women <55 years)N years of follow-up, mean (SD), range (<55 years)
Black Women's Health Study (10)United States37.1 (8.6)20–541995Mailed questionnaire91,299Self-report and state registry52,54312.6 (5.6)0–18.6
California Teachers Cohort (28)United States40.4 (7.4)22–541995–1998Mailed questionnaire41,185State registry47,51611.6 (5.0)0.0–17.2
Campaign against Cancer and Heart Disease (CLUE II; ref. 13)United States39.6 (9.6)18–541989Administered questionnaire6131State registry5,67110.8 (5.4)0.3–26.0
Canadian Study of Diet, Lifestyle, and Health (12)bCanada44.1 (6.9)23–541991–1999Mailed questionnaire1377Provincial and national registry1,5898.1 (4.7)0–18.6
European Prospective Investigation into Cancer and Nutrition (14)cEurope44.2 (8.1)19–541991–2000Self-reported/administered questionnaires12,122Self-report and national/regional registries150,2917.5 (4.2)0–16.6
Etude Epidémiologique auprès de femmes de la Mutuelle Générale de l'Education Nationale (E3N; ref. 15)France46.5 (4.2)38–541989–1991Mailed questionnaire81,908Self-report72,7488.1 (4.2)0–16.4
Generations Study (11)United Kingdom39.8 (9.5)16–542003–2012Mailed questionnaire2719Self-report and national registry72,0585.4 (1.7)0–9.7
Helseundersøkelsen i Nord-Trøndelag (HUNT2; ref. 26)Norway38.9 (9.7)20–541995–1997Administered questionnaire1209National cancer registry20,97410.2 (4.1)0.3–14.0
Melbourne Collaborative Cohort Study (16)Australia47.5 (4.4)31–541990–1994Administered questionnaire3227State registry12,0297.3 (4.4)0–20.1
New York University Women's Health Study (19, 20)United States45.2 (5.5)31–541984–1991Self-administered questionnaire6371Self-report and state registry8,7579.5 (5.5)0–23.5
Norwegian Women and Cancer Study (105)Norway45.7 (6.0)31–541991–2007Mailed questionnaire32,124National registry117,6339.0 (5.8)0.3–20.5
Nurses' Health Study (17)United States42.6 (7.1)29–541976–1978Mailed questionnaire162,743Self-report117,73012.2 (7.0)0.1–25.5
Nurses' Health Study II (18)United States34.8 (4.7)24–441989–1990Mailed questionnaire123,765Self-report116,41518.7 (3.7)0.1–23.7
Radiation Effects Research Foundation Life Span Study (21)Japan41.3 (8.5)18–541963–1993Administered or mailed questionnaire6130City registry18,42013.5 (8.5)0.1–36.7
Singapore Chinese Health Study (22)Singapore49.6 (3.0)43–541993–1998Administered questionnaire2134National cancer registry16,0565.3 (3.0)0.3–11.5
Sister Study (6)United States47.9 (4.9)35–542003–2009Telephone and written questionnaire3679Self-report24,0444.7 (2.5)0.1–10.6
Southern Community Cohort Study (23)United States47.3 (4.2)40–542002–2009Administered questionnaire2233State registry30,2895.1 (2.4)0.1–13.3
Sweden Women's Lifestyle and Health Study (27)Sweden39.7 (5.8)29–491991–1992Mailed questionnaire21,192National registry49,01014.4 (5.3)0.1–21.1
Swedish Mammography Cohort (24)Sweden46.6 (4.3)38–541987–1990Mailed questionnaire2649National registry34,1268.3 (4.3)0–16.6
United States Radiologic Technologist Cohort (25)United States36.8 (7.3)22–541983–1998Mailed questionnaire31,570Self-report62,86214.5 (5.6)0–22.8
  • aContributed as of June 2016; includes baseline and each follow-up.

  • bThe Canadian Study of Diet, Lifestyle, and Health is the only case-cohort study. The cohort size (N = 1,589) represents the subcohort only.

  • cThe European Prospective Study into Cancer and Nutrition (EPIC) dataset does not include the French or Norwegian EPIC sites which contributed from the Etude Epidémiologique auprès de femmes de la Mutuelle Générale de l'Education Nationale and Norwegian Women and Cancer Study directly.