Table 6.

Odds ratios per 10 cm³ of dense tissue as measured by Volpara (Volpara Health Technologies Ltd) within subgroups of 7019 assessment cases in the UK Breast Screening Programme.

Variable	Subgroup	OR per 10 cm3	95% CI	Significance
Age (years)	<50	1.02	0.97–1.07	p = 0.3
	50–59	1.04	1.02–1.07	p < 0.001
	≥60	1.02	1.00–1.05	p = 0.03
Dominant radiological feature	Mass	1.00	0.96–1.04	p = 0.8
	Calcification	1.04	1.02–1.07	p < 0.001
	Asymmetry/architectural distortion	1.03	1.00–1.06	p = 0.03
Recalled by 2D mammography	No	1.04	1.00–1.07	p = 0.01
	Yes	1.03	1.01–1.05	p < 0.001
Recalled by 2D + DBT	No	1.01	0.96–1.06	p = 0.5
	Yes	1.03	1.01–1.05	p = 0.001
Recalled by synthetic 2D + DBT	No	1.02	0.98–1.06	p = 0.4
	Yes	1.03	1.00–1.05	p = 0.002
Invasive status	Non-invasive	1.03	1.00–1.06	p = 0.01
	Invasive	1.03	1.01–1.05	p < 0.001
Node status of tumour (invasive only)	Negative	1.02	1.00–1.05	p = 0.01
	Positive	1.03	1.01–1.06	p < 0.001
Size of tumour (invasive only)	1–10 mm	1.01	0.98–1.04	p = 0.6
	11–20 mm	1.03	1.00–1.05	p = 0.004
	>20 mm	1.06	1.03–1.08	p < 0.001
Histological grade of tumour (invasive only)	1	1.03	1.00–1.06	p = 0.01
	2	1.02	1.00–1.05	p = 0.02
	3	1.04	1.00–1.08	p = 0.001
Total population	–	1.03	1.01–1.05	p < 0.001

Notes Asymmetry/architectural distortion: forms of asymmetrical breast density visible from the mammogram.