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Table 1 Estimates of increase in 10-year mortality for different prognostic groups and for false-negative rates of 9.7%, 20% and 100% (all values are in percentages)

From: A mathematical model for the effect of a false-negative sentinel node biopsy on breast cancer mortality: a tool for everyday use

     

ER-negative patientsa

     

Age 40 years

Age 60 years

     

Grade 3

Grade 2

Grade 1

Grade 3

Grade 2

Grade 1

     

<1 cm

1–2 cm

<1 cm

1–2 cm

<1 cm

1–2 cm

<1 cm

1–2 cm

<1 cm

1–2 cm

<1 cm

1–2 cm

Row

Risk/risk reduction

FNR

Explanation of calculations

ENPb

(15%)

(35%)

(12%)

(30%)

(10%)

(25%)

(15%)

(35%)

(12%)

(30%)

(10%)

(25%)

1

10-year mortality risk in NN women

   

8

17

5

14

3

6

3

6

5

14

3

6

2

10-year mortality real risk in those with 1–3 positive nodes

   

33

33

30

30

13

13

33

33

30

30

13

13

3

Reduction in 10-year mortality with adjuvant therapy in NN women

   

3.8

7.6

2.4

6.3

1.3

2.8

0.8

1.6

1.4

3.8

0.8

1.6

4

Reduction in 10-year mortality with adjuvant therapy in NP women (as would apply to the false-negative patients)

   

14.2

14.2

13

13

6.1

6.1

8.1

8.1

7.5

7.5

3.4

3.4

5

Difference in absolute benefit between NN and NP women from chemotherapy (NP - NN)

   

10.4

6.6

10.6

6.7

4.8

3.3

7.3

6.5

6.1

3.7

2.6

1.8

6

                

7

Unsuspected harm in a SNB-negative woman = (overall risk for missing positive axilla [AFN = FNR × ENP] × difference between benefit for NP and NN women [NP - NN]) + (harm from axillary relapse [AFN × 0.1])

9.7%

Actual % of patients with missed positive axilla (AFN = ENP × FNR)

1.5

3.4

1.2

2.9

1.0

2.4

1.5

3.4

1.2

2.9

1.0

2.4

8

  

Mortality due to axillary recurrence (AFN × 0.1)

0.15

0.34

0.12

0.29

0.10

0.24

0.15

0.34

0.12

0.29

0.10

0.24

9

  

Mortality due to no chemotherapy (AFN × [NP - NN])

0.15

0.22

0.12

0.19

0.05

0.08

0.11

0.22

0.07

0.11

0.03

0.04

10

  

Total

0.30

0.56

0.24

0.49

0.14

0.32

0.25

0.56

0.19

0.40

0.12

0.29

11

Unsuspected harm in a SNB-negative woman = (overall risk for missing positive axilla [AFN = FNR × ENP] × difference between benefit for NP and NN women [NP - NN]) + (harm from axillary relapse [AFN × 0.1])

20.0%

Actual % of patients with missed positive axilla (AFN = ENP × FNR)

3.0

7.0

2.4

6.0

2.0

5.0

3.0

7.0

2.4

6.0

2.0

5.0

12

  

Mortality due to axillary recurrence (AFN × 0.1)

0.30

0.70

0.24

0.60

0.20

0.50

0.30

0.70

0.24

0.60

0.20

0.50

13

  

Mortality due to no chemotherapy (AFN × [NP - NN])

0.31

0.46

0.25

0.40

0.10

0.17

0.22

0.46

0.15

0.22

0.05

0.09

14

  

Total

0.61

1.16

0.49

1.00

0.30

0.67

0.52

1.16

0.39

0.82

0.25

0.59

15

Unsuspected harm in a SNB-negative woman = (overall risk for missing positive axilla [AFN = FNR × ENP] × difference between benefit for NP and NN women [NP - NN]) + (harm from axillary relapse [AFN × 0.1])

100.0%

Actual % of patients with missed positive axilla (AFN = ENP × FNR)

15

35

12

30

10

25

15

35

12

30

10

25

16

  

Mortality due to axillary recurrence (AFN × 0.1)

1.50

3.50

1.20

3.00

1.00

2.50

1.50

3.50

1.20

3.00

1.00

2.50

17

  

Mortality due to no chemotherapy (AFN × [NP - NN])

1.56

2.31

1.27

2.01

0.48

0.83

1.10

2.28

0.73

1.11

0.26

0.45

18

  

Total

3.06

5.81

2.47

5.01

1.48

3.33

2.60

5.78

1.93

4.11

1.26

2.95

  1. The values for patients aged 40 years with a grade 2 or 3 tumour between 1 and 2 cm may be ignored because the benefit from chemotherapy is high (>5%) even if they are node negative. A 100% false-negative rate would be achieved if no axillary surgery was performed. aThe values given are for oestrogen receptor (ER)-negative patients and approximate those for additional benefit from chemotherapy in ER-positive patients on top of hormone therapy. bEstimated node positivity (ENP) is given in parentheses. AFN, estimated number of patients with a falsely negative axilla; FNR, false-negative rate; NN, node negative; NP, node positive.