Breast cancer risk in relation to occupations with exposure to carcinogens and endocrine disruptors: a Canadian case–control study

Table 8 Breast cancer odds ratios (matched analysis) in selected major sectors on tumor estrogen receptor status, and with interaction on prior farm work

Tumor receptor status	ER+/PR+	ER+/PR-	ER-
N cases (total=1006)	538	157	188
Model 1 – Cumulative exposure, ¹ no interactions
	OR (95% CI) Wald P (two-tailed)
Farming	1.32 (0.94-1.85) 0.12	1.35 (0.73-2.49)	1.71 (1.12-2.62) 0.014
Metalworking	2.03 (1.11-3.71) 0.022	1.73 (0.77-3.89)	1.02 (0.36-2.89)
Bars, gambling	3.87 (1.39-10.8) 0.010	3.24 (0.44-24.1)	0.15 (0.00-4.27)
Auto industry: plastics	3.63 (1.90-6.94) 9×10^-5	1.17 (0.28-4.97)	1.76 (0.78-3.94)
Canning	1.50 (0.55-4.10)	4.01 (1.37-11.8) 0.011	3.19 (1.16-8.75) 0.024
Model 2 – Cumulative exposure with prior farm interaction terms (IpAg)
	OR (95% CI) Wald P (two-tailed)
Farming	1.32 (0.93-1.87)	1.34 (0.70-2.57)	1.76 (1.13-2.74) 0.012
Metalworking	2.21 (1.14-4.30) 0.019	1.51 (0.65-3.50)	1.17 (0.43-3.13)
Metalworking … IpAg	0.84 (0.53-1.32)	1.26 (0.95-1.67) 0.11	0.47 (0.12-1.93)
Bars, gambling	2.87 (0.93-8.84) 0.066	2.78 (0.35-22.1)	0.20 (0.01-5.45)
Bars, gambling … IpAg	3.03 (0.74-12.4) 0.12	3.46 (0.27-45.0)	0.00 (0.00->100)
Auto industry: plastics	3.13 (1.62-6.05) 7×10^-4	1.26 (0.30-5.32)	0.96 (0.31-2.99)
Auto plastics… IpAg	2.10 (0.52-8.43)	0.65 (0.03-15.3)	3.03 (0.80-11.6) 0.10
Canning	1.52 (0.51-4.51)	1.21 (0.26-5.60)	4.85 (1.25-18.8) 0.022
Canning… IpAg	0.91 (0.51-1.65)	1.81 (1.08-3.04) 0.025	0.62 (0.22-1.72)

Odds ratios (OR) by conditional logistic regression with terms for reproductive, demographic risk factors as in Table 4 and terms for employment duration; matching on age in 3-year intervals; models include all major sector exposures; IpAg, interaction with farming: cumulative (sector rating × prior cum. exposure in agriculture); breast cancer cases not of the specified receptor type were excluded from analysis.
OR for cumulative exposure evaluated at 10.0 year in high-exposed jobs (lagged 5 year) or, for interactions, at 10 years in high-exposed jobs and 1 year in prior high-exposed farm work.