Brassiere wearing and breast cancer risk: A systematic review and meta-analysis

Table 1 United States Preventive Services Task Force Quality Rating Criteria (Case-Control study)

Criteria

Accurate ascertainment of cases

Nonbiased selection of cases/controls with exclusion criteria applied equally to both

Response rate

Diagnostic testing procedures applied equally to each group

Measurement of exposure accurate and applied equally to each group

Appropriate attention to potential confounding variable

Definition of ratings based on above criteria

Good: Appropriate ascertainment of cases and nonbiased selection of case and control participants; exclusion criteria applied equally to cases and controls; response rate equal to or greater than 80%; diagnostic procedures and measurements accurate and applied equally to cases and controls; and appropriate attention to confounding variables

Fair: Recent, relevant, without major apparent selection or diagnostic work-up bias but with response rate less than 80% or attention to some but not all important confounding variables

Poor: Major selection or diagnostic work-up biases, response rates less than 50%, or inattention to confounding variables

Table 2 Study characteristics

Ref.	Design	Country	No. of participants		Source of participants		Age of participants		Years of residence of participants	Residential status of participants	Age-match between participants	Ratio of cases to controls	Diagnosis of breast cancer status
			Cases	Controls	Cases	Controls	Cases	Controls					Casescontc	Controls
Hsieh et al[3]	Case-control	Greece, United States, Wales, Brazil, Yugoslavia, Taiwan, Japan	2325	7008	Hospital	Same hospital as cases	Over 35 years old	Over 35 years old	Not reported	Yes	± 2 yr	1:3	Diagnosed in hospital	Not reported
Feng et al[20]	Case-control	China	262	262	Hospital	Same hospital as cases, relative/neighbor of index case	Not reported	Not reported	Not reported	Yes	± 5 yr	1:1	Diagnosed in hospital	Not reported
Lee et al[10]	Case-control	Taiwan	250	219	Out-patient clinic or cancer center	Same as cases	Mean: 47.2;	Mean: 46.4	Not reported	Yes	± 5 yr	1:1	Pathological examination	Mammogram
Zhu et al[9]	Case-control	China	246	246	Hospital	Same hospital as cases; relative/neighbor of index case	Mean: 50.4	Mean: 50.0	Not reported	Not reported	± 5 yr	1:1	Diagnosed in hospital	Not reported
Zhang et al[11]	Case-control	China	284	669	Hospital	Health check program	Over 35 years old	Over 35 years old	Not reported	Yes	Not reported	1:3	Pathological examination	Not reported
Chen[21]	Case-control	China	167	334	Hospital	Neighbor	Not reported	Not reported	Over 10 years	Yes	± 2 yr	1:2	Diagnosed in hospital	Not reported
Hu and Lin[16]	Case-control	China	95	95	Hospital	Same hospital as cases	Median: 48	Median: 48	Over 10 years	Yes	Not reported	1:1	Pathological examination	Not reported
Liu et al[15]	Case-control	China	365	365	Not reported	Randomly obtained from population	Mean: 46.4	Mean: 45.6	Over 10 years	Yes	± 3 yr	1:1	Pathological examination	Not reported
Yao et al[13]	Case-control	China	200	200	Hospital	Same hospital	Mean: 47.30	Mean: 45.88	Over 10 years	Yes	± 2 yr	1:1	Pathological examination	Not reported
Chen et al[19]	Case-control	United States	Ducta: 454 Lobular: 590	469	Cancer Surveillance System	Randomly obtained from population	Between 55-74	Between 55-74	Not reported	Yes	± 5 yr	1:1:1	Pathological examination and tumor tissue specimens	Not reported
Liu et al[14]	Case-control	China	208	416	Hospital	Coworker/neighbor	Mean: 50.1	Mean: 49.2	Over 5 years	Yes	± 5 yr	1:2	Pathological examination	Not reported
Shen et al[12]	Case-control	China	275	275	Hospital	Not reported	Mean: 45.6	Mean: 48.5	Not reported	Yes	Not reported	1:1	Pathological examination	Physical examination

Table 3 Evidence table of brassiere wearing and breast cancer risk

Ref.	Study years	Area of brassiere exposure								Effect size: OR (95%CI)	Adjusted covariates		Study quality
		Duration of Brassiere wearing per day	Brassiere users	Sleeping with brassiere	Tightness of brassiere wearing	Wear underwired brassiere	Age began brassiere wearing	Brassiere cup size 1 yr before reference data	Appropriateness of brassiere wearing		Modifiable	Non-modifiable
Hsieh et al[3]	Not reported		Yes							(Premenopausal) non-brassiere-users vs brassiere-users: 0.44 (0.17-1.15)	Age at first birth Parity Obesity	Age at interview Study center	Fair
Feng et al[20]	1 yr			Yes	Yes					Sleep without brassiere vs with brassiere: 0.26 (0.09-0.77) Tightness of brassiere wearing: Not significant	Occupational contact of chemicals Emotional adjustment Psychological distress History of abortion Diet (high fat, rich in beans, take breakfast, drink tea) Night work Personality	History of benign breast disease Family history of breast cancer Menarche history	Fair
Lee et al[10]	3 yr	Yes		Yes						Wear brassiere (≥ 12 h/d) vs (< 12 h/d) (> age 40): 3.0 (1.6-5.7) Wear brassiere (≥ 13 h/d) vs ( ≤ 13 h/d) (all ages): 2.1 (1.3-3.3) Sleep with brassiere: Not significant	Physical activity Education High fat food Supplement and allium use Total calories	Age	Good
Zhu et al[9]	1 yr			Yes	Yes					Sleep with brassiere vs without brassiere: 2.32 (1.32-4.10) Tightness of brassiere wearing: Not significant	Parity Diet (high fat, rich in beans, drink tea) Psychological distress Personality Occupational contact of chemicals	Menarche history Family history of breast cancer History of benign breast disease	Fair
Zhang et al[11]	10 mo			Yes						(Premenopausal) sleep without brassiere vs with brassiere: 0.401 (0.250-0.644) Post-menopausal: not significant	Oral contraceptive use Physical activity Education Emotional problem/adjustment	Family history of breast cancer History of benign breast disease or breast biopsy Breast pain during menstruation	Fair
Chen[21]	2 yr			Yes	Yes					Both are not significant	Body mass index Lactation Oral contraceptive use Education Psychological distress Smoking history Night work Diet Occupational contact of chemicals or radiation	Age Family history of breast cancer History of benign breast disease Age at menarche and menopause	Fair
Hu and Lin[16]	3 yr					Yes				Wear brassiere with an underwire (Yes vs No): 6.729 (2.001-22.635)	Lactation Oral contraceptive use Sexual life Passive smoking Psychological distress Diet (fried and oily food) Sleeping hours History of abortion	History of benign breast disease, cervical disease, ovarian cancer, hepatitis -	Fair
Liu et al[15]	3 yr			Yes						Sleep with brassiere vs without brassiere: 2.313 (1.323-4.121)	Lactation Parity History of abortion Age at first birth Occupational contact of chemicals Passive smoking Diet (high fat, spicy/salty food, preserved food, seafood, drink water) Psychosocial problem (trauma, family problem, distress, anger)	Age at menarche Family history of breast cancer -	Fair
Yao et al[13]	15 mo			Yes		Yes				Sleep with brassiere vs without brassiere: 1.902 (1.177-3.072) Wear brassiere with an underwire (Yes vs No): Not significant	Large scale renovation Non-environmental friendly decoration materials Interval between renovations Nature of occupation Lactation Number of birth labour Job-related life events Fruit intake High fat intake Salted food intake Workplaces condition Sleeping hours and quality -	Family history of other tumors Family history of breast cancer History of cancer in first degree relatives Mammary hyperplasia The death of a loved one	Fair
Chen et al[19]	4 yr 3 mo	Yes				Yes	Yes	Yes		All are not significant	Education Annual household income BMI Bra band size Age at first full-term pregnancy Mammogram screening Parity Use of hormonal therapy	Race/ethnicity Family history of breast cancer Types of menopause	Good
Liu et al[14]	2 yr 7 mo	Yes								Wear brassiere (≥ 12 h/d) vs (< 12 h/d): 1.064 (1.001-1.132)	Income Occupation Oral contraceptive use Passive smoking Use of royal jelly Use of other supplement Work-related stress Personality Emotional adjustment Interpersonal relationship Contact of chemicals Psychological distress Adverse life events Sleeping hours	History of benign breast disease	Fair
Shen et al[12]	4 yr								Yes	Appropriately wearing vs inappropriately wearing: 2.313 (1.112-5.43)	History of abortion Lactation Work intensity Long working hours Poor sleep quality Family discord Satisfaction towards life Fatigue strength Smoking	Family history of other tumors Family history of breast cancer Mammary hyperplasia	Fair