Urinary phthalate exposures and risk of breast cancer: the Multiethnic Cohort study

Wu, Anna H.; Franke, Adrian A.; Wilkens, Lynne R.; Tseng, Chiuchen; Conroy, Shannon M.; Li, Yuqing; Polfus, Linda M.; De Rouen, Mindy; Caberto, Christian; Haiman, Christopher; Stram, Daniel O.; Le Marchand, Loïc; Cheng, Iona

doi:10.1186/s13058-021-01419-6

Breast Cancer Research

Table 1 Study characteristics of breast cancer cases nested within the Multiethnic Cohort (MEC)

From: Urinary phthalate exposures and risk of breast cancer: the Multiethnic Cohort study

	All cases		Controls
	N = 1032	%	N = 1030	%
Area
Hawaii	883	85.6	881	85.5
Los Angeles	149	14.4	149	14.5
Urine type^a
First morning	157	15.2	157	15.2
Overnight	875	84.8	873	84.8
Mean age at urine collection, yrs ± SD	66.7 ± 7.7		66.8 ±7.7
≤ 64	487	47.2	470	45.6
65–74	376	36.4	387	37.6
75+	169	16.4	173	16.8
Race/ethnicity
Japanese American	478	46.3	478	46.4
White	274	26.6	273	26.5
African American (AA)	48	4.7	49	4.8
Latino	77	7.5	76	7.4
Native Hawaiian (NH)	155	15.0	154	15.0
Education
≤ High school	420	40.7	424	41.2
Some college	216	20.9	217	21.1
College graduate	192	18.6	202	19.6
Graduate school	199	19.3	180	17.5
Missing	5	0.5	7	0.7
Age at menarche, yrs
< 12	555	53.8	570	55.3
13–14	370	35.9	359	34.9
> 14	100	9.7	95	9.2
Missing	7	0.7	6	0.6
Number of children
Nulliparous	163	15.8	111	10.8
1 child	98	9.5	116	11.3
2–3 children	523	50.7	553	53.7
> 4 children	245	23.7	245	23.8
Missing	3	0.3	5	0.5
Age at first live birth, yrs
Nulliparous	163	15.8	111	10.8
15–20	211	20.4	208	20.2
21–30	564	54.7	614	59.6
> 30	82	7.9	76	7.4
Missing	12	1.2	21	2.0
Menopausal status
Premenopause	213	20.6	208	20.2
Natural menopause	509	49.3	505	49.0
Other surgery	120	11.6	134	13.0
Surgical menopause	160	15.5	154	15.0
Other or missing reasons	30	2.9	29	2.8
Use of hormone therapy at urine collection
Never estrogen (E])	400	38.8	409	39.7
Past E	337	32.7	350	34.0
Current E alone	186	18.0	184	17.9
Current E + progesterone	100	9.7	78	7.6
Missing	9	0.9	9	0.9
Neighborhood SES at urine collection
Quintile 1–low	100	9.7	123	11.9
Quintile 2	147	14.2	153	14.9
Quintile 3	154	14.9	162	15.7
Quintile 4	233	22.6	220	21.4
Quintile 5–high	345	33.4	316	30.7
Missing	53	5.1	56	5.4
BMI at urine collection (kg/m²)
Mean BMI ± SD	27.1 ± 5.6		26.0 ± 5.6
< 25	406	39.3	529	51.4
≥ 25- < 30	366	35.5	316	30.7
≥ 30	260	25.2	185	18.0
Waist-hip ratio (WHR)^d
Mean ± SD	0.862 ± 0.076		0.858 ± 0.082
< 0.854	384	37.2	475	46.1
≥ 0.854	457	44.3	471	45.7
Missing	191	18.5	84	8.2
Waist (inches)^d
Mean ± SD	35.51 ± 5.51		34.72 ± 5.47
< 34	331	32.1	425	41.3
≥ 34	513	49.7	524	50.9
Missing	188	18.2	81	7.9
Smoking status
Never	578	56.0	618	60.0
Former	315	30.5	300	29.1
Current	133	12.9	104	10.1
Missing	6	0.6	8	0.8
Mediterranean diet score^e
Quartile 1–low	350	33.9	350	34.0
Quartile 2	207	20.1	204	19.8
Quartile 3	220	21.3	204	19.8
Quartile 4–high	232	22.5	252	24.5
Missing	23	2.2	20	1.9
Stage^b
In situ	224	21.7
I (1)	613	59.4
II (2)	10	1.0
III (3,4,7)	175	17.0
Missing	10	1.0
Hormone receptor (HR) status^c
Estrogen (ER) + or progesterone (PR)	859	83.2
ER− and PR−	124	12
Missing	49	4.7

^aAll urines from Los Angeles were first morning samples. All urines from Hawaii were overnight (99%) or first morning urines (1%)
^bOf the 10 missing stage, 2 were ER+ or PR+, 2 were ER− and PR−, and 6 were missing stage
^cOf the 49 missing HR status, there were 35 in situ, 6 stage I, 1 stage II, 1 stage III, and 6 missing stage
^dWaist-hip ratio (WHR) information was collected at the third follow-up questionnaire (2003–2006); we included subjects with WHR information before breast cancer diagnosis and for all control women
^eThe Mediterranean diet included 9 components (vegetables, fruit, nuts, legumes, whole grains, fish, alcohol, monounsaturated: saturated fat ratio, and red/processed meat) (Ref [26], Harmon et al.)

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ISSN: 1465-542X

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