Characteristics of the patients
A total of 5760 patients were screened for eligibility, and 2602 were excluded: 48 with a history of breast cancer, 879 with a history of breast surgery, 401 with chronic inflammation at baseline, 1141 with incomplete blood routine data at the first health examination, and 133 with abnormal absolute monocyte counts or percentage of monocyte. Therefore, the final study population includes 3158 participants. During a total of 6037 person-years of follow-up (median follow-up time, 2.35 years), breast lumps were found in 803 patients (Fig. 2).
Table 1 presents the baseline characteristics of the participants according to the breast lump status during follow-up. Compared with women without a breast lump, those with a breast lump were younger, more likely to have a lower BMI, WC, SBP, DBP, TC, TG, LDL-C, FBG, UA, %LY, and a history of hypertension and diabetes and more likely to have a higher AMC and %MONO (all P<0.05). No significant differences were observed between the two groups for HDL-C, WBC, ANC, AEC, ABC, ALC, AMC, %NEUT, %EO, %BASO, RBC, Hb, PLT, marital status, drinking status, family history of cancer, hypertension, diabetes, and history of cancer (all P>0.05).
Table 1 Characteristics of the participants according to the presence of a by breast lump
Characteristics
|
Breast Lump
|
P value
|
No (N=2355)
|
Yes (N=803)
|
Age (years)
|
46.6 (36.7, 56.3)
|
45.2 (38.2, 52.2)
|
0.01
|
BMI (kg/m2)
|
23.60 (21.40, 26.06)
|
23.38 (21.30, 25.60)
|
0.05
|
WC (cm)
|
80.0 (73.0, 86.0)
|
77.0 (72.0, 84.5)
|
<0.01
|
SBP (mmHg)
|
120 (110, 135)
|
109 (100, 118)
|
<0.01
|
DBP (mmHg)
|
75 (68, 84)
|
75 (66, 80)
|
<0.01
|
TC (mmol/L)
|
5.03 (4.40, 5.75)
|
4.91 (4.29, 5.57)
|
<0.01
|
TG (mmol/L)
|
1.11 (0.80, 1.58)
|
1.04 (0.77, 1.49)
|
0.01
|
LDL-C (mmol/L)
|
2.90 (2.34, 3.49)
|
2.77 (2.24, 3.38)
|
<0.01
|
HDL-C (mmol/L)
|
1.47 (1.26, 1.71)
|
1.49 (1.27, 1.72)
|
0.30
|
FBG (mmol/L)
|
4.9 (4.6, 5.3)
|
4.8 (4.6, 5.2)
|
<0.01
|
UA (mmol/L)
|
267 (233, 311)
|
260 (227, 300)
|
<0.01
|
WBC (×109/L)
|
5.36 (4.58, 6.32)
|
5.39 (4.61, 6.34)
|
0.68
|
ANC (×109/L)
|
3.05 (2.46, 3.77)
|
3.08 (2.49, 3.85)
|
0.40
|
%NEUT (%)
|
57.0 (51.9, 62.5)
|
57.8 (52.6, 63.1)
|
0.08
|
AEC (×109/L)
|
0.08 (0.05, 0.13)
|
0.08 (0.05, 0.14)
|
0.96
|
%EO (%)
|
1.6 (1.0, 2.5)
|
1.6 (1.0, 2.5)
|
0.92
|
ABC (×109/L)
|
0.03 (0.02, 0.04)
|
0.03 (0.02, 0.04)
|
0.75
|
%BASO (%)
|
0.5 (0.4, 0.7)
|
0.5 (0.4, 0.7)
|
0.79
|
ALC (×109/L)
|
1.79 (1.49, 2.12)
|
1.77 (1.49, 2.11)
|
0.21
|
%LY (%)
|
34.0 (28.8, 38.6)
|
32.8 (28.4, 38.0)
|
0.01
|
AMC (×109/L)
|
0.34 (0.28, 0.41)
|
0.35 (0.29, 0.41)
|
0.03
|
%MONO (%)
|
6.3 (5.4, 7.3)
|
6.5 (5.5, 7.5)
|
0.03
|
RBC (×1012/L)
|
5.36 (4.58, 6.32)
|
5.39 (4.61, 6.34)
|
0.70
|
Hb (g/L)
|
135 (129, 141)
|
134 (127, 141)
|
0.50
|
PLT (×109/L)
|
251 (216, 288)
|
257 (217, 294)
|
0.65
|
Marital statusa
|
|
|
|
Married
|
1857 (78.9)
|
628 (78.2)
|
0.10
|
Unmarried
|
155 (6.6)
|
39 (4.8)
|
Others†
|
24 (1.0)
|
13 (1.6)
|
Smoking statusb
|
|
|
|
Never
|
2232 (94.8)
|
771 (96.0)
|
0.06
|
Ever
|
38 (1.6)
|
8 (0.9)
|
Now
|
18 (0.8)
|
1 (0.1)
|
Drinking statusc
|
|
|
|
No
|
2108 (89.5)
|
707 (88.0)
|
0.34
|
Yes
|
180 (7.6)
|
73 (9.1)
|
Family history of disease
|
|
|
|
Cancer
|
244 (10.4)
|
90 (11.2)
|
0.50
|
Hypertension
|
921 (39.1)
|
32.8 (40.8)
|
0.38
|
Diabetes
|
477 (20.3)
|
173 (21.5)
|
0.44
|
History of chronic disease
|
|
|
|
Cancer
|
26 (1.1)
|
11 (1.4)
|
0.55
|
Hypertension
|
291 (12.4)
|
67 (8.3)
|
<0.01
|
Diabetes
|
89 (3.8)
|
14 (1.7)
|
<0.01
|
BMI, body mass index; WC, waist circumference; SBP, systemic blood pressure; DBP, diastolic blood pressure; TC, total cholesterol; TG, triglyceride; LDL-C, low-density lipoprotein; HDL-C, high-density lipoprotein; FBG, fasting blood glucose; UA, uric acid; WBC, white blood cell; ANC, absolute neutrophil count; NEUT, neutrophil percentage; AEC, absolute eosinophils count; %EO, eosinophils percentage; ABC, absolute basophil count; %BASO, basophil percentage; ALC, absolute lymphocyte count; %LY, lymphocyte percentage; AMC, absolute monocyte count; %MONO, monocyte percentage; RBC, red blood cell; Hb, hemoglobin; PLT, platelet.
Data are presented as medians (ranges) or n (%).
P-values <0.05 are considered statistically significant.
†Others includes separated, divorced, and widowed.
adata about marital status were missing in 123 patients with a breast lump and 319 patients without breast lump;
bdata about smoking status were missing in 23 patients with a breast lump and 67 patients without breast lump;
cdata about drinking status were missing in 23 patients with a breast lump and 67 patients without breast lump.
Association of AMC and %MONO with breast lump
Table 2 presents the crude and adjusted associations of AMC and %MONO with the incidence of a breast lump. AMC and %MONO levels (both as quartiles and as continuous variables) were positively associated with the incidence of breast lump in all models. In the final multivariable-adjusted models, using the lowest quartile as the reference group, the HRs (95%CIs) of breast lump were 1.18 (95%CI: 0.95, 1.45), 1.33 (95%CI: 1.08, 1.65), and 1.28 (95%CI: 1.02, 1.61), respectively, for AMC in the 2nd, 3rd, and 4th quartiles (P for trend <0.001). The corresponding HRs (95%CI) for %MONO in the 2nd, 3rd, and 4th quartiles were 1.03 (95%CI: 0.83, 1.28), 1.28 (95%CI: 1.03, 1.29), and 1.62 (95%CI: 1.30, 2.02), respectively (P for trend <0.001). The multivariable-adjusted HRs for breast lump per unit increase of AMC and %MONO were 3.19 (95%CI: 1.38, 7.38; P=0.007) and 1.14 (95%CI: 1.08, 1.21; P<0.001), respectively.
Table 2 Adjusted relationships of absolute monocyte count and percentage of monocyte to the incident of the breast lump.
|
Level 1
|
Level 2
|
Level 3
|
Level 4
|
P for trend
|
Continuous
|
P value
|
Absolute monocyte count
|
|
|
|
|
|
|
|
Range
|
≤ 0.29
|
0.30-0.35
|
0.36-0.42
|
≥ 0.43
|
-
|
-
|
-
|
Person-years of follow up
|
1793
|
1591
|
1404
|
1248
|
-
|
-
|
-
|
No. of breast lump
|
203
|
221
|
203
|
176
|
-
|
-
|
-
|
Model 1
|
1.00 (reference)
|
1.23 (1.01, 1.48)
|
1.34 (1.11, 1.63)
|
1.28 (1.05, 1.57)
|
0.002
|
3.15 (1.51, 6.58)
|
0.002
|
Model 2
|
1.00 (reference)
|
1.23 (1.02, 1.49)
|
1.40 (1.15, 1.70)
|
1.34 (1.09, 1.65)
|
<0.001
|
3.88 (1.83, 8.26)
|
<0.001
|
Model 3
|
1.00 (reference)
|
1.18 (0.95, 1.45)
|
1.33 (1.08, 1.65)
|
1.28 (1.02, 1.61)
|
0.007
|
3.19 (1.38, 7.38)
|
0.007
|
Monocyte percentage
|
|
|
|
|
|
|
|
Range
|
≤ 5.40
|
5.41-6.40
|
6.41-7.50
|
≥ 7.51
|
-
|
-
|
-
|
Person-years of follow up
|
1687
|
1675
|
1503
|
1172
|
-
|
-
|
-
|
No. of breast lump
|
199
|
195
|
212
|
197
|
-
|
-
|
-
|
Model 1
|
1.00 (reference)
|
1.05 (0.86, 1.28)
|
1.32 (1.09, 1.60)
|
1.64 (1.35, 2.00)
|
<0.001
|
1.15 (1.09, 1.21)
|
<0.001
|
Model 2
|
1.00 (reference)
|
1.05 (0.86, 1.28)
|
1.33 (1.09, 1.62)
|
1.69 (1.39, 2.07)
|
<0.001
|
1.16 (1.10, 1.22)
|
<0.001
|
Model 3
|
1.00 (reference)
|
1.03 (0.83, 1.28)
|
1.28 (1.03, 1.59)
|
1.62 (1.30, 2.02)
|
<0.001
|
1.14 (1.08, 1.21)
|
<0.001
|
Confidence intervals (CIs) not including 1.00 are considered statistically significant.
Model 1: crude hazard ratios (HRs) with corresponding 95% CIs were calculated.
Model 2: adjusted for age and BMI as potential confounding variables.
Model 3: adjusted for age, BMI, WC, SBP, DBP, TC, TG, LDL-C, HDL-C, FBG, UA, marital status, smoking status, drinking status, family history of cancer, hypertension, diabetes, history of cancer, history of hypertension, and history of diabetes.
Cumulative incidence of breast lump stratified by age
Figure 3 shows the cumulative incidence of breast lump stratified by age and quartile of AMC and %MONO; these data indicated that the effect of high monocyte levels on increased risks of a breast lump was more remarkable in women <60 years of age (both P<0.05), while no significant differences were observed for women >60 years of age (both P>0.05).