Table 2 Hot flash frequency and severity and pharmacological and biochemical parameters of study participants during treatment with tamoxifen

Pre-treatment history of hot flashes

0.04

   No

82 (75%)

47 (84%)

35 (66%)

   Yes

27 (25%)

9 (16%)

18 (34%)

Median frequency of hot flashes per week

21

21

21

0.77

   Range

0 - 168

0 - 168

0 - 168

Average severity of hot flashes

0.56

   None

17 (16%)

9 (16%)

8 (15%)

   Mild

22 (20%)

13 (23%)

9 (17%)

   Moderate

55 (50%)

26 (46%)

29 (55%)

   Severe

11 (10%)

7 (12%)

4 (8%)

   Very severe

4 (4%)

1 (2%)

3 (6%)

Median tamoxifen (ng/mL)

95.4

93.8

97.9

0.61

   Range

39.7 - 237

50.0 - 220

39.7 - 237

Median N-desmethyltamoxifen (ng/mL)

181

177

187

0.82

   Range

82.3 - 532

94.3 - 532

82.3 - 439

Median endoxifen (ng/mL)

9.12

8.59

9.16

0.75

   Range

1.73 – 22.6

1.73 – 20.3

2.14 – 22.6

Median 4-hydroxytamoxifen (ng/mL)

1.69

1.77

1.43

0.91

   Range

0.74 - 4.23

0.74 - 4.23

0.78 - 3.51

Median estradiol (pmol/L)

0.06

   <LLOQ*

70

33

37

   43.0 – 67.0

12

6

6

   67.0 – 361

14

8

6

   >361

11

9

2

   Missing

2

0

2

CYP2D6 phenotype

0.66

   Extensive metabolizer

54 (50%)

28 (50%)

26 (49%)

   Intermediate metabolizer

30 (28%)

19 (34%)

11 (21%)

   Poor metabolizer

5 (5%)

2 (4%)

3 (6%)

   Missing

20 (18%)

7 (12%)

13 (24%)