Breast cancer risk in women ever exposed to organic solvents or ever exposed to benzene by selected breast cancer risk factors and risk of breast cancer subtypes
| Factor | Ever exposed to total organic solvents OR*, †; 95% CI | Ever exposed to benzene OR*, ‡; 95% CI | ||||
| Menopause (n cases/controls) | Pre- (104/121) | Post- (318/288) | Pre- (21/31) | Post- (94/89) | ||
| 1.21 (0.9 to 1.6) | 1.15 (0.96 to 1.4) | 0.78 (0.4 to 1.4) | 1.06 (0.8 to 1.4) | |||
| p Heterogeneity | 0.74 | 0.58 | ||||
| Age (n cases/controls) | <50 (121/122) | ≥50 (301/287) | <50 (25/28) | ≥50 (90/92) | ||
| 1.13 (0.8 to 1.5) | 1.20 (0.99 to 1.5) | 0.90 (0.5 to 1.6) | 1.04 (0.8 to 1.4) | |||
| p Heterogeneity | 0.73 | 0.71 | ||||
| Family history of breast cancer (n cases/controls) | Yes (49/28) | No (373/381) | Yes (10/10) | No (105/110) | ||
| 1.08 (0.6 to 1.9) | 1.18 (1.0 to 1.4) | 0.49 (0.2 to 1.3) | 1.07 (0.8 to 1.4) | |||
| p Heterogeneity | 0.67 | 0.11 | ||||
| Age at menarche¶ (n cases/controls) | ≤12 (132/91) | >12 (289/312) | ≤12 (37/32) | >12 (78/86) | ||
| 1.25 (0.9 to 1.7) | 1.15 (0.96 to 1.4) | 0.88 (0.5 to 1.5) | 1.09 (0.8 to 1.5) | |||
| p Heterogeneity | 0.16 | 0.44 | ||||
| BMI¶ (n cases/controls) | <25 (155/129) | ≥25 (266/277) | <25 (49/33) | ≥25 (65/86) | ||
| 1.16 (0.9 to 1.5) | 1.19 (0.98 to 1.4) | 1.33 (0.8 to 2.2) | 0.85 (0.6 to 1.2) | |||
| p Heterogeneity | 0.94 | 0.19 | ||||
| Parity (n cases/controls) | Nulliparous (59/41) | Parous (363/368) | Nulliparous (26/12) | Parous (89/108) | ||
| 1.22 (0.8 to 1.9) | 1.17 (0.99 to 1.4) | 1.94 (0.9 to 4.1) | 0.88 (0.7 to 1.2) | |||
| p Heterogeneity | 0.81 | 0.04 | ||||
| Alcohol consumption (n cases/controls) | Abstinents (267/252) | Ever consumers (155/157) | Abstinents (80/78) | Ever consumers (35/42) | ||
| 1.22 (1.0 to 1.5) | 1.11 (0.9 to 1.4) | 1.12 (0.8 to 1.6) | 0.83 (0.5 to 1.3) | |||
| p Heterogeneity | 0.49 | 0.29 | ||||
| Pathomorphological breast cancer feature Cancer type (n cases) | Ductal NOS (222) | Lobular (55) | Ductal NOS (61) | Lobular (14) | ||
| 1.18 (0.98 to 1.4) | 1.05 (0.8 to 1.4) | 1.00 (0.7 to 1.4) | 0.83 (0.5 to 1.5) | |||
| p Heterogeneity | 0.48 | 0.55 | ||||
| Tumour size (n cases) | ≤2 cm (200) | >2 cm (156) | ≤2 cm (47) | >2 cm (47) | ||
| 1.20 (0.99 to 1.5) | 1.15 (0.9 to 1.4) | 0.84 (0.6 to 1.2) | 1.08 (0.8 to 1.5) | |||
| p Heterogeneity | 0.74 | 0.26 | ||||
| Grade (n cases) | Well differentiated (42) | Moderately (220) | Poorly (84) | Well differentiated (14) | Moderately (54) | Poorly (25) |
| 1.42 (0.98 to 2.0) | 1.20 (0.99 to 1.4) | 1.10 (0.8 to 1.4) | 1.50 (0.8 to 2.7) | 0.88 (0.6 to 1.2) | 0.97 (0.6 to 1.5) | |
| p Heterogeneity | 0.38§ | 0.24§ | 0.09§ | 0.21§ | ||
↵* Adjusted for age, study site, education, body mass index (BMI), age at menarche, menopausal status, age at menopause (in postmenopausal women), number of full-term births, age at first full-term birth, breastfeeding, family history of breast cancer and previous screening mammography.
↵† Never exposed to organic solvents used as referent.
↵‡ Never exposed to benzene used as referent.
↵§ Compared with well differentiated.
↵¶ There was missing information for age at menarche in one case and six controls exposed to organic solvents and two controls exposed to benzene; BMI (in one case and three controls exposed to organic solvents and one case and one control exposed to benzene).