Table 5.

Random-effects meta-analysis for the association between a $10\text{-}{\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$ increase in exposure to particulate matter with an aerodynamic diameter below $10\mathrm{\mu }\mathrm{m}$ (${\mathrm{PM}}_{10}$) and breast cancer onset: main analyses, sensitivity analyses (SA, based on the main analysis not corrected for publication bias), and supplementary analyses according to the menopausal status or the hormonal receptor subtype.

Meta-analysis	$n$ effect estimates	$n$ cases	$n$ participants	RR (95% CI)	$I^2$ (%)	Heterogeneity $p$-valuea
Main analysis (not corrected for publication bias)b	13	23,765	1,326,524	1.058 (0.994, 1.126)	27.6	0.14
Main analysis (corrected for publication bias)b	16	24,228c	1,337,704c	1.047 (0.984, 1.113)	27.5	0.13
SA1. Leave-one-out meta-analysisd	12	14,188	305,492	1.023 (0.975, 1.073)	3.9	0.69
SA2. Restricted to prospective cohort studies	11	13,023	303,056	1.023 (0.971, 1.078)	7.6	0.61
SA3. Restricted to European populations	10	14,800	1,105,581	1.119 (0.998, 1.254)	14.9	0.43
SA4. Restricted to North American populations	3	8,965	220,943	1.017 (0.973, 1.062)	0.0	0.74
SA5. Restricted to studies with adjustment for main reproductive factorse	4	8,455	198,823	1.019 (0.964, 1.078)	0.0	0.84
SA6. Restricted to studies with adjustment for socioeconomic contextf	10	11,878	280,179	1.023 (0.965, 1.085)	11.6	0.53
SA7. Restricted to effect estimates reported in “all women” onlyg	6	20,852	1,267,288	1.058 (0.990, 1.131)	48.1	0.079
SA8. Excluding CECILE case–control study (not published yet)	12	22,600	1,324,088	1.058 (0.991, 1.130)	33.0	0.10
SA9. Restricted to studies with exposure assessment based on precise home addressesh	12	14,188	305,492	1.023 (0.975, 1.073)	3.9	0.69
SA10. Restricted to studies with exposure assessment based on residential historyi	4	8,455	198,823	1.019 (0.964, 1.078)	0.0	0.84
SA11. Restricted to studies with exposure assessment based on modeling dataj	11	17,620	1,153,014	1.084 (0.987, 1.192)	24.0	0.15
SA12. Restricted to studies with recruitment starting in 2000 or latek	4	13,630	1,072,832	1.129 (0.929, 1.373)	49.2	0.033
In premenopausal women	3	2,849	NAl	0.992 (0.894, 1.100)	4.7	0.37
In postmenopausal women	10	6,692	NAl	1.013 (0.932, 1.102)	9.6	0.53
Hormone responsive positive ($\text{ER}+/\text{PR}+$)	4	5,917	NAl	1.012 (0.955, 1.072)	0.0	0.75
Hormone responsive negative ($\text{ER}–/\text{PR}–$)	4	1,338	NAl	0.991 (0.807, 1.217)	39.4	0.13

Note: Studies included in sensitivity analyses (SA): SA1: All but AOK PLUS; SA2: CEANS, DCH, DNC, EPIC-NL, EPIC-Oxford, EPIC-Turin, HUBRO, MEC, NHSII, Sister Study, VHM&PP; SA3: AOK PLUS, CEANS, CECILE, DCH, DNC, EPIC-NL, EPIC-Oxford, EPIC-Turin, HUBRO, VHM&PP; SA4: MEC, NHSII, Sister Study; SA5: CECILE, DNC, MEC, NHSII; SA6: CEANS, DCH, EPIC-NL, EPIC-Oxford, EPIC-Turin, HUBRO, MEC, NHSII, Sister Study, VHM&PP; SA7: AOK PLUS, CECILE, DNC, MEC, NHSII, Sister Study; SA8: All but CECILE; SA9: CEANS, CECILE, DCH, DNC, EPIC-NL, EPIC-Oxford, EPIC-Turin, HUBRO, MEC, NHSII, Sister Study, VHM&PP; SA10: CECILE, DNC, MEC, NHSII; SA11: AOK PLUS, CEANS, CECILE, DCH, DNC, EPIC-NL, EPIC-Oxford, EPIC-Turin, HUBRO, Sister Study, VHM&PP; SA12: AOK PLUS, CECILE, HUBRO, Sister Study; In premenopausal women: CECILE, NHSII, Sister Study; In postmenopausal women: CEANS, CECILE, DCH, EPIC-NL, EPIC-Oxford, EPIC-Turin, HUBRO, NHSII, Sister Study, VHM&PP; On hormonal receptor subtypes: CECILE, MEC, NHSII, Sister Study. CI: confidence interval: .

^aCochrane’s heterogeneity Q test.

^bEffect estimates reported in studies led in postmenopausal women only were included in the main meta-analysis in addition to the effect estimates reported in “all women” (i.e., irrespective of menopausal status).

^cEffectives simulated by trim-and-fill analysis.

^dI.e., excluding the study contributing the most to the between-study heterogeneity (Figure S3).

^eAge at menarche, age at the first full-term pregnancy, and parity.

^fAt the area level.

^gI.e., irrespective of menopausal status.

^hI.e., excluding studies in which air pollutant levels were assessed at the postal code scale.

ⁱI.e., excluding studies in which air pollutant levels were assessed for a single home address.

^jI.e., from land-use regression (LUR), dispersion model (DM), or chemistry-transport model (CTM).

^kBecause of stronger potential for exposure misclassification in studies recruiting subjects before 2000.

^lSample size could not be calculated due to missing information in source studies.