Skip to main content

Table 1 Distributions of breast cancer risk factors in Kenyan breast cancer patients, overall and by hospitals (N=838)

From: Breast cancer risk factors in relation to molecular subtypes in breast cancer patients from Kenya

   Hospitals
Overall (n=838) AKU (n=350, 42%) Kijabe (n=105, 13%) Nyeri (n=110, 13%) St Mary’s (n=122, 15%) Others (n=151, 18%)  
N % N % N % N % N % N % P*
Demographic
Age at diagnosis/year
  20–29 32 3.8 17 4.9 2 1.9 2 1.9 5 4.1 6 4.0 0.11
  30–39 177 21.2 64 18.3 23 21.9 22 20.4 34 28.1 34 22.5  
  40–49 242 29.0 100 28.7 37 35.2 34 31.5 35 28.9 36 23.8  
  50–59 211 25.3 105 30.1 26 24.8 23 21.3 19 15.7 38 25.2  
  ≥ 60 172 20.6 63 18.1 17 16.2 27 25.0 28 23.1 37 24.5  
  Mean (SD) 49.2 (12.8) 49.0 (11.2) 48.4 (11.3) 50.5 (13.5) 48.7 (15.1) 49.7 (12.9)        
  Median (IQR) 48 (39, 57) 49 (40, 56) 47 (41, 57) 49 (41, 60) 45 (37, 58) 49 (39, 59)        
  Missing 4   1   0   2   1   0   
BMI/ kg/m2
  Normal (< 25.0) 210 31.3 67 21.3 35 40.2 25 39.7 36 40.4 47 40.2 < 0.0001
  Overweight (25.0–29.9) 264 39.3 126 40.0 33 37.9 28 44.4 37 41.6 40 34.2  
  Obese (≥ 30.0) 197 29.4 122 38.7 19 21.8 10 15.9 16 18.0 30 25.6  
  Missing 167   35   18   47   33   34   
Family history of breast cancer in first-degree female relatives
  No 773 92.2 314 89.7 100 95.2 99 90.0 119 97.5 141 93.4 0.036
  Yes 65 7.8 36 10.3 5 4.8 11 10.0 3 2.5 10 6.6  
Occupation              
  Farmer 253 30.3 47 13.4 43 41.0 82 74.5 39 32.5 42 27.8 < 0.0001
  Employed worker 195 23.3 138 39.4 16 15.2 5 4.5 10 8.3 26 17.2  
  Trader 155 18.5 66 18.9 24 22.9 2 1.8 35 29.2 28 18.5  
  Housewife 156 18.7 68 19.4 19 18.1 8 7.3 27 22.5 34 22.5  
  Casual worker 32 3.8 11 3.1 3 2.9 4 3.6 8 6.7 6 4.0  
  Other 45 5.4 20 5.7 0 0.0 9 8.2 1 0.8 15 9.9  
  Missing 2   0   0   0   2   0   
Highest education level
  None 257 30.7 54 15.4 41 39.0 44 40.0 57 46.7 61 40.4 < 0.0001
  Primary 163 19.5 40 11.4 22 21.0 29 26.4 36 29.5 36 23.8  
  Secondary 209 24.9 99 28.3 24 22.9 31 28.2 21 17.2 34 22.5  
  Tertiary 209 24.9 157 44.9 18 17.1 6 5.5 8 6.6 20 13.2  
Place of residence              
  Rural 511 61.0 173 49.4 79 75.2 99 90.0 65 53.3 95 62.9 < 0.0001
  Urban 327 39.0 177 50.6 26 24.8 11 10.0 57 46.7 56 37.1  
Exposure to smoking†
  Never exposed 477 56.9 248 70.9 63 60.0 39 35.5 63 51.6 64 42.4 < 0.0001
  Exposed 361 43.1 102 29.1 42 40.0 71 64.5 59 48.4 87 57.6  
Alcohol use              
  No 760 90.7 304 86.9 98 93.3 109 99.1 115 94.3 134 88.7 0.0009
  Yes 78 9.3 46 13.1 7 6.7 1 0.9 7 5.7 17 11.3  
Ethnicity              
  Bantu 656 78.3 266 76.0 92 87.6 109 99.1 106 86.9 83 55.0 < 0.0001
  Nilote 141 16.8 65 18.6 5 4.8 0 0.0 10 8.2 61 40.4  
  Cushite/Mixed 41 4.9 19 5.4 8 7.6 1 0.9 6 4.9 7 4.6  
Reproductive
Age at menarche/year
  9–12 68 8.5 30 8.6 10 11.1 7 6.9 7 5.8 14 10.0 0.40
  13–14 340 42.4 150 42.9 31 34.4 39 38.2 61 50.8 59 42.1  
  15–20 394 49.1 170 48.6 49 54.4 56 54.9 52 43.3 67 47.9  
 Missing 36   0   15   8   2   11   
Age at first pregnancy/year
  Nulliparous‡ 37 4.5 23 6.6 4 3.9 2 1.9 2 1.8 6 4.0 < 0.0001
  < 20 216 26.3 62 17.7 29 28.4 34 31.8 38 34.2 53 35.3  
  20–24 361 44.0 142 40.6 41 40.2 54 50.5 52 46.8 72 48.0  
  25–29 150 18.3 90 25.7 21 20.6 14 13.1 14 12.6 11 7.3  
  ≥ 30 56 6.8 33 9.4 7 6.9 3 2.8 5 4.5 8 5.3  
  Missing 18   0   3   3   11   1   
Number of children
  Nulliparous‡ 44 5.3 26 7.4 6 5.7 2 1.8 2 1.6 8 5.3 0.0001
  1 or 2 226 27.0 110 31.4 25 23.8 25 22.7 34 27.9 32 21.2  
  3 or 4 307 36.6 135 38.6 43 41.0 47 42.7 34 27.9 48 31.8  
  ≥ 5 261 31.2 79 22.6 31 29.5 36 32.7 52 42.6 63 41.7  
Cumulative breastfeeding duration/month
  Nulliparous‡ 37 4.6 23 6.6 4 4.0 2 1.9 2 1.7 6 4.2 0.013a
  Never breastfed 7 0.9 3 0.9 2 2.0 0 0.0 0 0.0 2 1.4  
  Q1: 1−< 39 191 23.5 82 23.7 27 27.0 23 21.3 32 27.8 27 18.9  
  Q2: 39–< 62 192 23.6 100 28.9 28 28.0 24 22.2 16 13.9 24 16.8  
  Q3: 62–< 96 182 22.4 80 23.1 17 17.0 28 25.9 24 20.9 33 23.1  
  Q4: ≥ 96 203 25.0 58 16.8 22 22.0 31 28.7 41 35.7 51 35.7  
  Missing 26   4   5   2   7   8   
Averaged breastfeeding duration per child/month
  Nulliparous‡ 37 4.6 23 6.6 4 4.0 2 1.9 2 1.7 6 4.2 0.0036a
  Never breastfed 7 0.9 3 0.9 2 2.0 0 0.0 0 0.0 2 1.4  
  < 12 120 14.8 53 15.3 23 23.0 8 7.4 18 15.7 18 12.6  
  12–23 407 50.1 153 44.2 46 46.0 71 65.7 64 55.7 73 51.0  
  ≥ 24 241 29.7 114 32.9 25 25.0 27 25.0 31 27.0 44 30.8  
  Missing 26   4   5   2   7   8   
Number of children and cumulative breastfeeding duration
  Nulliparous or ≤3 children and < 62 months 354 43.60 179 51.7 44 44.0 43 39.8 44 38.3 44 30.8 < 0.0001
  ≤ 3 children and ≥ 62 months 79 9.73 43 12.4 5 5.0 10 9.3 8 7.0 13 9.1  
  ≥ 4 children and < 62 months 73 8.99 29 8.4 17 17.0 6 5.6 6 5.2 15 10.5  
  ≥ 4 children and ≥ 62 months 306 37.69 95 27.5 34 34.0 49 45.4 57 49.6 71 49.7  
  Missing 26   4   5   2   7   8   
Age at first pregnancy and number of children
  Nulliparous 44 5.36 26 7.4 6 5.8 2 1.9 2 1.8 8 5.3 < 0.0001
  Age 25+ years, 1–3 births 154 18.76 98 28.0 16 15.5 13 12.1 13 11.7 14 9.3  
  Age < 25 years, 1–3 births 244 29.72 101 28.9 27 26.2 38 35.5 37 33.3 41 27.3  
  Age 25+ years, 4+ births 49 5.97 23 6.6 12 11.7 4 3.7 6 5.4 4 2.7  
  Age < 25 years, 4+ births 330 40.20 102 29.1 42 40.8 50 46.7 53 47.7 83 55.3  
  Missing 17   0   2   3   11   1   
Menopausal status
  Premenopausal 438 52.4 183 52.3 64 61.0 50 45.5 67 55.4 74 49.3 0.18
  Postmenopausal 398 47.6 167 47.7 41 39.0 60 54.5 54 44.6 76 50.7  
  Missing 2   0   0   0   1   1   
Age at menopause/yearb
  < 50 191 57.4 91 55.8 18 62.1 28 59.6 20 71.4 34 51.5 0.45b
  ≥ 50 142 42.6 72 44.2 11 37.9 19 40.4 8 28.6 32 48.5  
  Missing 65   4   12   13   26   10   
Cumulative hormonal contraception exposure/month
  < 48 216 45.9 88 46.3 25 44.6 26 40.0 27 34.6 50 61.0 0.014
  48 255 54.1 102 53.7 31 55.4 39 60.0 51 65.4 32 39.0  
  Missing 367   160   49   45   44   69   
  1. * P values were computed from chi-square tests except where noted. P values less than 0.05 are shown in bold font. a Nulliparous women and parous women who never breastfed were grouped together in chi-square test. bChi-square test was performed restricted to postmenopausal women. † Only 3.58% (n=30) of study participants reported ever having smoked or used smokeless tobacco. Exposure to smoking is summarized here as exposed/never exposed, where exposed is defined as personal use of tobacco as well as exposure to smoke at the workplace or home during child or adulthood. ‡ Nulliparous cases were women who reported never pregnant, never given birth, and had no children (N=37, 4.4%). AKU, Aga Khan University; BMI, body mass index; IQR, interquartile range; Q, quartile; SD, standard deviation.