An investigation of breast cancer risk factors in Cyprus: a case control study

BMC Cancer

Table 1 Socio-demographic characteristics and potential risk factors among participants.

Characteristic	Cases (N = 1109)		Controls (N = 1177)
	N	%	N	%	p-value¹
Age
<45	121	10.9	68	5.8
45-54	354	31.9	440	37.4
55-64	394	35.5	526	44.7
≥65	240	21.6	140	11.9
Not reported	0	0.0	3	0.3	<0.01²
Mean (SD)	56.1 (9.1)		55.7 (7.0)		0.22 ³
Education
Primary	418	37.7	464	39.4
Secondary	412	37.2	435	37.0
Tertiary	131	11.8	147	12.5
University	135	12.2	122	10.4
Not reported	13	1.2	9	0.8	0.51
Marital status
Married	921	83.1	1015	86.2
Widowed/Divorced	130	11.7	117	9.9
Single	57	5.1	42	3.6
Not reported	1	0.1	3	0.3	0.09
BMI
<18.5	13	1.2	11	0.9
18.5-24.5	314	28.3	322	27.4
25-29.5	368	33.2	463	39.3
≥30	337	30.4	269	22.9
Not reported	77	6.9	112	9.5	<0.001
Family history of breast cancer
No	953	85.9	1068	90.7
Yes	156	14.1	107	9.1
Not reported	0	0.0	2	0.2	<0.001
Age at menarche
≤11 years	157	14.2	134	11.4
12-14 years	798	72.0	838	71.2
≥15 years	154	13.9	205	17.4	0.02
Pregnancy⁴
Yes	1021	92.1	1110	94.3
No	88	7.9	67	5.7	0.03
Number of children⁴
None	103	9.3	88	7.5
One	90	8.1	82	7.0
Two	480	43.3	492	41.8
Three or more	436	39.3	515	43.8	0.10
Age at 1st pregnancy⁵
<30	851	83.4	971	87.5
≥30	140	13.7	116	10.5
Not reported	30	2.9	23	2.1	0.03
Breastfeeding⁵
Never	305	29.9	279	25.1
≤6 months	329	32.2	385	34.7
7-12 months	166	16.3	181	16.3
More than 1 year	221	21.7	265	23.9	0.09
Oral contraceptive use
No	823	74.2	879	74.7
Yes	280	25.3	294	25.0
Not reported	6	0.5	4	0.3	0.76
HRT use
Never	937	84.5	838	71.2
<6 months	41	3.7	64	5.4
6-60 months	86	7.8	182	15.5
≥60 months	45	4.1	92	7.8
Not reported	0	0.0	1	0.1	<0.001
Smoking
Never	869	78.4	955	81.1
Past	130	11.7	76	6.5
Current	108	9.7	143	12.2
Not reported	2	0.2	3	0.3	<0.001
Exercise⁶
Yes	544	49.1	635	54.0
No	563	50.8	539	45.8
Not reported	2	0.2	3	0.3	0.06

Notes: ¹P-value of χ² test for independence. ²Differences in the age distribution among cases and controls are mainly driven by the under-representation of controls in the younger and older age-groups. After restricting to ages 45-65, p-value becomes 0.46. ³P-value of t-test for difference in mean age between cases and controls. ⁴The difference in number of women reporting not having had a pregnancy (N = 155) and not having had a child (N = 191) is due to the fact that 15 and 21 women in cases and controls respectively have reported been pregnant not resulting in birth. ⁵Restricted to those women who have had a pregnancy. ⁶Only information on current exercise status was available.

ISSN: 1471-2407