Shin et al reported a nomogram for predicting a positive resection margin following breast-conserving surgery for breast cancer. The authors are from Chung-Ang University and Seoul National University Hospital in South Korea.
Patient selection: breast-conserving therapy for a breast cancer
Parameters:
(1) mammographic density based on percent fibroglandular tissue
(2) microcalcifications
(3) difference in tumor size between MRI and US in cm (MRI-US)
(4) DCIS on needle biopsy
(5) lobular component on needle biopsy
Parameter
Finding
Points
mammographic density
Grade 1 (< 25%)
0
Grade 2 (26 to 50%)
19.8
Grade 3 (51 to 75%)
20.2
Grade 4 (> 75%)
65.3
microcalcifications
no
0
yes
19.3
MRI-US
<= 0.5
0
> 0.5
100
DCIS
no
0
yes
19.3
lobular component
no
0
yes
59.8
score =
= SUM(points for the 5 parameters)
Interpretation:
• minimum score: 0
• maximum score: 263.7
• The higher the score the greater the likelihood of a positive margin.
Score
Probability of Positive Margin
< 28.3
< 5%
28.3 to 216
X = (0.02304 * (score)) - 3.5852;
probability of positive margin = 1/(1 +EXP((-1) * X))
> 216
> 80%
Performance:
• The area under the ROC curve is 0.82.
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