Preoperative risk of positive surgical margins in breast-conserving surgery
This prediction tool calculates the estimated risk of positive surgical margins in T1-T2 breast cancer patients who consider breast-conserving surgery (c-index: 0.70).

The ability to estimate the preoperative risk of positive margins following lumpectomy could support clinicians in counseling patients regarding the likelihood of requiring further surgery, allowing for a more patient-tailored approach.
Research authors: Pleijhuis RG, Kwast AB, Jansen L, de Vries J, Lanting R, Bart J, Wiggers T, van Dam GM, Siesling S.
Details Formula Study characteristics Files & References
Model author
Model ID
Revision date
MeSH terms
  • Breast Cancer
  • Breast Carcinoma
  • Breast-Conserving Surgery
  • Surgery, Breast-Conserving
  • Model type
    Logistic regression (Calculation)
    No Formula defined yet
    Condition Formula

    Additional information

    Patients with clinical T1-2N0-1Mx-0 histology-proven invasive breast carcinoma who underwent BCT throughout the North-East region of The Netherlands between June 2008 and July 2009 were selected from the Netherlands Cancer Registry (n = 1185). Positive surgical margin status was defined as microscopically confirmed invasive carcinoma and/or DCIS at the inked margin of the lumpectomy specimen following the first attempt at lumpectomy. Results from multivariate logistic regression analyses served as the basis for development of the prediction tool.

    Study Population

    Total population size: 1185
    Males: {{ model.numberOfMales }}
    Females: {{ model.numberOfFemales }}

    Continuous characteristics

    Name Mean SD Unit
    Age 59.8 0.31 years
    Tumor size 15.6 0.22 mm
    Area on mammogram 17916 6807 mm2
    Weight excised lump 62.5 39.7 gram
    Tumor-to-lump index 0.338 0.012 (index)

    Categorical characteristics

    Name Subset / Group Nr. of patients
    Age <40 years 39
    40-70 years 919
    >70 years 227
    Tumor size pT1a 54
    pT1b 243
    pT1c 599
    pT2 284
    pT3 5
    Area on mammogram <15.000 mm2 450
    15.000-25.000 mm2 554
    >25.000 mm2 181
    Weight excised <50 gram 270
    50-100 gram 172
    >100 gram 165
    Tumor-to-lump index <0.25 278
    0.25-0.50 228
    >0.50 101
    Palpability Palpable 637
    Non-palpable 548
    Tumor location LOQ 122
    UOQ 535
    UIQ 189
    LIQ 150
    Central 103
    Histological type Ductal 957
    Lobular 119
    Specified 109
    Histological grade Grade I 330
    Grade II 531
    Grade III 313
    ER status Positive 1002
    Negative 172
    PR status Positive 750
    Negative 300
    Her2/neu receptor status Positive 125
    Negative 1041
    Multifocal disease Yes 47
    No 1138
    pN-stage Positive 310
    Negative 875
    Prior surgery to the breast Yes 46
    No 1139
    Family history FDR 91
    SDR 188
    Negative 749
    BI-RADS classification II 3
    III 93
    IV 611
    V 447
    Preoperative MRI Yes 122
    No 1063
    Microcalcifications Yes 245
    No 937
    DCIS component present Yes 529
    No 656
    Breast density 0-25% 323
    25-50% 467
    50-75% 217
    75-100% 34
    Institution University-affiliated 642
    Community hospital 543
    Preoperative risk of positive surgical margins in breast-conserving surgery
    Refer to Intended Use for instructions before use
    Evidencio B.V., Irenesingel 19, 7481 GJ, Haaksbergen, the Netherlands
    Notes are only visible in the result download and will not be saved by Evidencio

    Estimated risk of positive surgical margins:

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    Outcome stratification

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    Conditional information

    Result interpretation

    Overall model performance:
    Model performance was validated on an external independent dataset (n=331) from the University Medical Center Groningen. Model calibration and discrimination were assessed graphically and by calculation of a concordance index, respectively. Concordance indices were calculated of 0.70 (95% CI: 0.66-0.74) and 0.69 (95% CI: 0.63-0.76) for the modeling and the validation group, respectively. Calibration of the model was considered adequate in both groups.

    External model validation
    In 2015, Barentsz et al. validated the model in their cohort of 576 Caucasian patients with non-palpable breast cancer from five hospitals. The authors reported a c-index of 0.617 (95% CI: 0.542-0.693). The authors mention that the difference in discriminative power might be related to differences in patient characteristics, as reflected by the difference in a priori probability of positive margins (21.4% vs. 12.0%). In addition, only non-palpable lesions were included in this study.

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    Calculations alone should never dictate patient care, and are no substitute for professional judgement. See our full disclaimer.

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