Pleijhuis et al reported a nomogram for predicting positive surgical margins at breast-conserving therapy for breast cancer. The authors are from University Medical Center Groningen and Twente University in The Netherlands.
Patient selection: breast cancer prior to breast-conserving therapy
Parameters:
(1) preoperative MRI
(2) microcalcifications
(3) density of breast tissue in percent
(4) preoperative N stage
(5) palpability
(6) preoperative T stage
(7) suspicion of multifocality
(8) presence of DCIS in core needle biopsy
(9) ER status
(10) histologic type
(11) histologic grade (Elston I, II or III)
Parameter
Finding
Points
preoperative MRI
yes
0
no
35.8
microcalcifications
no
0
yes
19.8
density of breast tissue
< 25%
0
25 to 50%
17
50.01 to 75%
34
> 75%
51
preoperative N stage
negative
0
positive
48.3
palpability
palpable
0
nonpalpable
35.8
preoperative T stage
T1
0
T2
24.7
focality
unifocal
0
multifocal
90.7
presence of DCIS
no
0
yes
100
ER status
negative
0
positive
51.9
histologic type
lobular
93.8
other
0
histologic grade
low or intermediate
0
high
35.8
total score =
= SUM(points for all 11 parameters)
Interpretation:
• minimum score: 0
• maximum score: 603.9
• The higher the score the greater the chances of a positive surgical margin.
Score
Probability of Positive Margin
< 156
< 10%
>= 156
X = (0.011285 * (score)) - 3.9899
probability = 1 / (1 + EXP((-1) * X))
Performance:
• The area under the ROC curve was 0.70.
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