Risk factors and natural history of breast cancer in younger Chinese women

Table 1 Sociodemographics and breast screening habits of the total patient cohort (n = 7152)

	< 40 yr (n = 1008) n (%)		≥40 yr (n = 6144) n (%)		P value
Age
< 20	1	(0)			--
20-29	84	(1.2)
30-39	923	(12.9)
40-49			2 978	(41.6)-
50-59			2 102	(29.4)
60-69			698	(9.8)
70-79			268	(3.7)
80+			98	(1.4)
Education level
No schooling	4	(0.4)	344	(5.7)	χ2 = 473.730, bP < 0.001
Primary	47	(4.7)	1 544	(25.5)
Secondary	488	(49.3)	2 986	(49.4)
Matriculation	133	(13.4)	425	(7)
Undergraduate/postgraduate	318	(32.1)	748	(12.4)
Occupation
Professional/Clerical	608	(63)	1 845	(31)	χ2 = 412.754, bP < 0.001
Non-clerical/Labor	126	(13.1)	1 298	(21.8)
Self-employed	45	(4.7)	190	(3.2)
Housewife	170	(17.6)	2 043	(34.3)
Retired/Unemployed	16	(1.7)	585	(9.8)
Monthly household income
< HK$10000	77	(10.4)	837	(22.5)	χ2 = 88.503, bP < 0.001
HK$10000-29999	290	(39.1)	1 591	(42.8)
≥ HK$30000	375	(50.5)	1 287	(34.6)
Breast screening habits
Breast self examination
Never	332	(33.8)	2 359	(39.7)	χ2 = 13.136, bP = 0.001
Occasional	428	(43.6)	2 295	(38.6)
Monthly	222	(22.6)	1 288	(21.7)
Clinical breast examination
Never	380	(38.5)	2 625	(44.1)	χ2 = 10.934, bP = 0.004
Occasional	132	(13.4)	718	(12.1)
Regular1	476	(48.2)	2 611	(43.9)
Mammogram
Never	--		3 929	(66.1)	--
Occasional	--		554	(9.3)
Regular1	--		1 463	(24.6)
Ultrasound
Never	--		4 029	(70.3)	--
Occasional	--		520	(9.1)
Regular1	--		1 179	(20.6)

¹Regular means having breast examinations annually, or once every 2-3 years.