Table 3.

Summary of study and participant characteristics.

Authors	Design	Geographic region	Cohort or participant source	Cases	Controls	Statistical covariates
Abbas – 2009	NCC	Germany	38 hospitals in southern Germany	N = 289 German speaking women aged 30–50, diagnosed with breast cancer by age 50 (premenopausal) between January 1992 and December 1995	N = 595 Selected from random list of residents. 2 controls matched to each case on age and study region.	Age, season of blood collection, number of births, family history, age at menarche, duration of breast-feeding, BMI, alcohol consumption Not significant: Age at first birth, smoking, education
Abulkhair – 2015	CS	Saudi Arabia	Oncology Department of King Abdulaziz Medical City	N = 406 (404 women, 2 men) Newly diagnosed cases of breast cancer. 87% Saudi nationality, median age 48.5	N/A	None
Crew – 2009	NCC	New York	Long Island Breast Cancer Study Project	N = 1026 English speaking women, average age 58.6, 94.4% white, living in Nassau and Suffolk counties, diagnosed with in situ or invasive cancer between August 1996 and July 1997	N = 1075 Frequency matched to the expected age distribution of case women by 5 year age groups. <65 years identified by random digit dialing. ≥65 identified from Health Care Financing Administration records.	Age, race, BMI, season of blood draw
Eliassen – 2011	NCC	US	Nurses Health Study II	N = 613 Cancer free cohort members from US women aged 32–54 who provided blood and urine samples between 1996–1999 and later developed breast cancer	N = 1218 2 controls matched to each case on age, menopausal status at diagnosis, ethnicity, luteal day, time of day and fasting status for blood draw	Age at menarche, BMI at age 18, parity, age at first birth, BMI at blood collection, family history, history of benign breast disease, age at blood collection, season, fasting status at blood collection, time of blood collection, luteal day, race, menopausal status
Eliassen − 2016	NCC	US	Nurses Health Study	N = 1506 Cancer free cohort members from US women aged 43–69 who donated blood samples from 1989–1990 and/or 2000–2002 and later developed breast cancer	N = 1506 One control for each case matched for age at donation, menopausal status and HRT use at blood collection and diagnosis, month, time of day and fasting status of blood collection	Fasting status, time of blood draw, age at blood draw, menopausal status and HRT, age at menarche, BMI at age 18, weight change from age 18 to blood draw, parity and age at first birth, family history of breast cancer, history of benign breast disease. Stratified by season.
Kuhn – 2013	NCC	Denmark, France, Germany, Greece, Italy, Norway, Spain, Sweden, The Netherlands, UK	European Prospective Investigation into Cancer and Nutrition (EPIC) – Includes cases from French E3N cohort, excludes Malmo Diet and Cancer Study participants	N = 1391 Women from the EPIC cohort diagnosed with breast cancer, but no previous cancer. Selection targeted premenopausal women and equal numbers of ER+ and ER− postmenopausal women.	N = 1391 No history of any cancer, matched for study center, age, menopausal status, oral contraceptive or HRT use at blood draw, time of day of blood collection, fasting status, phase of menstrual cycle	BMI, age at menarche, age at first full-term pregnancy, number of full-term pregnancies, breastfeeding, alcohol consumption, smoking status, education level, physical activity
McCullough – 2009	NCC	US	Cancer Prevention Study II (CPS-II)	N = 516 Postmenopausal women from the CPS-II cohort who reported a new incidence of breast cancer on a biennial follow up in June 2005. Age range 47–85, 96.7% white women.	N = 516 Matched on date of birth, race/ethnicity, date of blood collection	Adjusted for birth year, year of blood draw, race, season, parity and age at first birth, BMI at blood collection, weight change from age 18 to blood collection
Park – 2015	CC	Korea	Cases: Breast Cancer Center registry, Yonsei University College of Medicine Controls: KNHANES IV-2 -KNHANES V-3	N = 3634 Korean women, average age 50.7, treated for breast cancer between January 2006 and December 2012	N = 17,133 Matching criteria not stated	Age, residential regions, BMI, marriage status, age at menarche, menopausal status, age at first birth, oral contraceptives, HRT Age, laboratory, race, month of blood draw
Peppone – 2012	CC/CS	US	University of Rochester Medical Center	N = 194 US women with no previous cancer history diagnosed with breast cancer between January 2009 and November 2010	N = 194 Individuals with no history of cancer who had 25(OH)D measured for the first time between January 2009 and October 2010. Matched on age and date of blood collection
Rejnmark – 2009	NCC	Denmark	Women who received a diagnostic mammogram between May 2003 and July 2007 in Denmark	N = 142 Women, average age 58, from cohort who developed in situ or invasive breast cancer during the follow-up period and had no previous history of breast cancer.	N = 420 3 controls per case, when possible, with no history of breast cancer. Women matched on age, menopausal status, and season of blood sampling.	None stated
Scarmo – 2013	NCC	New York and Sweden	New York University Women’s Health Study (NYUWHS) and Sweden Mammary screening Cohort (NSMSC)	N = 1585 Women who were part of the NYUWHS cohort who developed breast cancer before January 2007 or part of the NSMSC cohort, who developed breast cancer before January 2010. Average age 58, 90% Caucasian, 6% African American.	N = 2940 2 controls per case, matched on age, date of blood donation, number and dates of subsequent blood donations. Additionally, NYUWHS cases were also matched for menopausal status and race/ethnicity	Age at menarche, family history, age at first birth/parity/nulliparous, BMI, HRT, alcohol consumption
Shirazi – 2016	NCC	Sweden	Malmo Diet and Cancer Study (MDCS)	N = 764 Women, average age 57, from MDCS diagnosed with breast cancer before December 31, 2006	N = 764 Matched on calendar time at inclusion, menopausal status, age at inclusion, and time of year of blood donation.	Age at baseline, month and year at baseline, menopausal status, HRT, socio-economic index
Yao – 2011	CC/CS	US	Data Bank and Biorepository at Roswell Park Cancer Institute (RPCI)	N = 579 Non-Hispanic white women with no previous history of cancer, enrolled from 2003–2008	N = 574 Family and friends of RCPI patients and visitors, but not family and friends of cases. Matched on age and month of blood draw.	Age at diagnosis, BMI. Stratified by menopausal status. Not significant: Physical activity
Yao – 2014	CS	US	Data Bank and Biorepository at Roswell Park Cancer Institute (RPCI)	N = 490 Non-Hispanic white women, average age 56.4, with no previous history of cancer, diagnosed between December 2003 and June 2009	N/A	Age at diagnosis, specimen storage time, season of blood draw, timing of blood draw in relation to receipt of treatment, tumor stage. Stratified by menopausal status. Not significant: family history, BMI, tumor grade, smoking status

Abbreviations: NCC – Nested case-control, CC – Case-control, CS – Case series, BMI – Body Mass Index, HRT – Hormone Replacement Therapy, BMI – Body Mass Index, ER – Estrogen Receptor, PR – Progesterone Receptor, TNBC – Triple Negative Breast Cancer, HER2 – Human Epidermal growth factor Receptor 2.