Smoking at time of diagnosis and breast cancer-specific survival: new findings and systematic review with meta-analysis

Table 2 Breast cancer-specific mortality according to smoking exposure at time of diagnosis among 5,892 women with invasive breast cancer (1987 to 2008)

Smoking status			Breast cancer-specific mortality
	Number of		Crude HR (95% CI)	Age^a-adjusted HR (95% CI)	Adjusted^bHR (95% CI)
	Women	Deaths	Crude HR (95% CI)	Age^a-adjusted HR (95% CI)	Adjusted^bHR (95% CI)
Never^c	3,510	583	1.00	1.00	1.00
Former	1,303	185	0.94 (0.79 to 1.11)	0.99 (0.84 to 1.17)	1.04 (0.88 to 1.24)
Current^d	1,079	185	0.99 (0.84 to 1.16)	0.99 (0.83 to 1.17)	1.15 (0.97 to 1.37)
≤15 pack years	232	40	0.82 (0.60 to 1.13)	0.73 (0.53 to 1.01)	0.92 (0.66 to 1.28)
>15 to ≤30 pack years	278	54	1.06 (0.80 to 1.40)	1.05 (0.79 to 1.39)	1.23 (0.92 to 1.64)
>30 pack years	273	58	1.20 (0.91 to 1.57)	1.35 (1.03 to 1.78)	1.52 (1.15 to 2.00)
P-value, test for trend^e			0.08	0.004	0.002
≤10 cigarettes/day	287	36	0.75 (0.54 to 1.05)	0.73 (0.52 to 1.02)	0.97 (0.69 to 1.37)
>10 to ≤20 cigarettes/day	395	75	1.05 (0.83 to 1.34)	1.06 (0.83 to 1.35)	1.13 (0.88 to 1.45)
>20 cigarettes/day	337	70	1.17 (0.91 to 1.50)	1.19 (0.92 to 1.53)	1.32 (1.02 to 1.70)
P-value, test for trend^e			0.06	0.04	0.03
≤20 years	191	44	1.06 (0.78 to 1.44)	0.87 (0.63 to 1.19)	1.05 (0.76 to 1.45)
21 to 30 years	258	49	0.93 (0.69 to 1.24)	0.92 (0.68 to 1.24)	1.06 (0.78 to 1.44)
>30 years	340	61	1.11 (0.85 to 1.45)	1.30 (1.00 to 1.70)	1.56 (1.19 to 2.05)
P-value, test for trend^e			0.67	0.07	0.004

^aHRs adjusted for age at diagnosis (≤39, 40 to 49, 50 to 59, 60 to 69, ≥70 years). ^bHRs adjusted for age at diagnosis (≤39, 40 to 49, 50 to 59, 60 to 69, ≥70 years), year of diagnosis (≤1994, 1995 to 1999, 2000 to 2004, ≥2005), age at menarche (≤11, 12, 13, ≥14 years), parity (0, 1, 2, ≥3), menopausal status (premenopausal, postmenopausal), current hormone replacement therapy use (yes, no), first degree family history of breast cancer (yes, no), estrogen and progesterone receptors positivity (positive, negative, not investigated), histological grade (well, moderately, poorly differentiated), size of the tumor (≤10, 11 to 20, 21 to 30, 31 to 40, >40 mm, no pathological investigation), regional or distant involvement (node-negative, 1 to 3 positive nodes, ≥4 positive nodes, unknown nodal involvement, distant metastases), locoregional treatment (mastectomy, breast-conserving surgery, no surgery), neoadjuvant therapy (yes, no), adjuvant endocrine therapy (yes, no), adjuvant chemotherapy (yes, no). ^cReference category. ^dAmong the 1,079 current smokers, number of pack years of smoking, number of cigarettes smoked and duration of smoking were unknown for 296, 60 and 290 women, respectively. ^eP for trend in hazard ratios comparing current smokers further categorized based on number of pack years of smoking, number of cigarettes smoked daily or duration of smoking, to never smokers. HR, hazard ratio; CI, confidence interval.

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