Table 2 Relative risks (RRs) and 95% confidence intervals for the association between FFQ-based estimated intake of lignans and postmenopausal breast cancer risk by receptor-defined subtype among 51 823 postmenopausal women in the Swedish Mammography Cohort

		Quartiles of estimated total lignan intake, μ g day ⁻¹
Categories for quartile		Q1	Q2	Q3	Q4
Lignan intake, μ g day ⁻¹	No. of cases	<712	712–866	867–1035	⩾1036	P ^a	P ^b
No of person-year		101 994	105 399	107 791	115 147
All invasive tumours
Age-adjusted RR	1284	1.00	0.86 (0.74–1.00)	0.87 (0.74–1.01)	0.86 (0.74–1.00)	0.09
Multivariable-adjusted RR^c	1284	1.00	0.83 (0.71-0.97)	0.83 (0.70-0.97)	0.83 (0.70-0.97)	0.042
ER+PR+tumours
Age-adjusted RR	716	1.00	0.82 (0.66-1.01)	0.90 (0.73-1.10)	0.89 (0.72-1.09)	0.44
Multivariable-adjusted RR^c	716	1.00	0.79 (0.63–0.97)	0.86 (0.69–1.06)	0.86 (0.69–1.08)	0.35
ER+PR−tumours
Age-adjusted RR	279	1.00	0.81 (0.59-1.12)	0.67 (0.48-0.94)	0.77 (0.56-1.07)	0.09
Multivariable-adjusted RR^c	279	1.00	0.77 (0.56–1.07)	0.64 (0.45–0.90)	0.77 (0.54–1.09)	0.12	0.65
ER−PR−tumours
Age-adjusted RR	143	1.00	0.85 (0.53-1.36)	0.93 (0.59-1.46)	0.87 (0.55-1.38)	0.66
Multivariable-adjusted RR^c	143	1.00	0.87 (0.54–1.40)	0.96 (0.60–1.54)	0.92 (0.56–1.52)	0.86	0.99

ER, oestrogen receptor; PR, progesterone receptor.
^aTwo sided P-values for trend were calculated using the Wald statistics using the median values for each category of intake of lignan as continuous variable.
^bP-values (two-sided) for heterogeneity from the Wald test compared with four pairs of β-coefficients of ER+PR+tumours.
^cMultivariable Cox proportional harzard models with age as the time-scales were adjusted for height (continuous), body mass index (<18.5, 18.5–24.9, 25–29.9, ⩾30 kg m⁻²), education (<12 years of education, ⩾12 years of education), parity (nulliparous, 1–2, ⩾3), age at first birth (nulliparous, <26, 26–30, ⩾31 years), age at menarche (⩽12, 13, ⩾14 years, missing), age at menopause (<51, ⩾51 years), type of menopause (natural, surgery), use of oral contraceptives (ever, never, missing), use of postmenopausal hormones (ever, never, missing), family history of breast cancer among first-degree relatives (yes/no), history of benign breast disease (yes/no), quintiles of total energy intake, quintiles of energy-adjusted total fat intake, and alcohol intake (nondrinkers, <3.4, 3.4–9.9, ⩾10.0 ethanol g day⁻¹).

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