Prediction of Upstaging in Ductal Carcinoma in Situ Based on Mammographic Radiomic Features

Abstract

Background Improving diagnosis of ductal carcinoma in situ (DCIS) before surgery is important in choosing optimal patient management strategies. However, patients may harbor occult invasive disease not detected until definitive surgery. Purpose To assess the performance and clinical utility of mammographic radiomic features in the prediction of occult invasive cancer among women diagnosed with DCIS on the basis of core biopsy findings. Materials and Methods In this Health Insurance Portability and Accountability Act-compliant retrospective study, digital magnification mammographic images were collected from women who underwent breast core-needle biopsy for calcifications that was performed at a single institution between September 2008 and April 2017 and yielded a diagnosis of DCIS. The database query was directed at asymptomatic women with calcifications without a mass, architectural distortion, asymmetric density, or palpable disease. Logistic regression with regularization was used. Differences across training and internal test set by upstaging rate, age, lesion size, and estrogen and progesterone receptor status were assessed by using the Kruskal-Wallis or χ² test. Results The study consisted of 700 women with DCIS (age range, 40-89 years; mean age, 59 years ± 10 [standard deviation]), including 114 with lesions (16.3%) upstaged to invasive cancer at subsequent surgery. The sample was split randomly into 400 women for the training set and 300 for the testing set (mean ages: training set, 59 years ± 10; test set, 59 years ± 10; P = .85). A total of 109 radiomic and four clinical features were extracted. The best model on the test set by using all radiomic and clinical features helped predict upstaging with an area under the receiver operating characteristic curve of 0.71 (95% CI: 0.62, 0.79). For a fixed high sensitivity (90%), the model yielded a specificity of 22%, a negative predictive value of 92%, and an odds ratio of 2.4 (95% CI: 1.8, 3.2). High specificity (90%) corresponded to a sensitivity of 37%, positive predictive value of 41%, and odds ratio of 5.0 (95% CI: 2.8, 9.0). Conclusion Machine learning models that use radiomic features applied to mammographic calcifications may help predict upstaging of ductal carcinoma in situ, which can refine clinical decision making and treatment planning. © RSNA, 2022.

Graphical abstract

Figure 1:

Illustration of the study pipeline (step 1). A total of 700 women were identified (step 2). Lesion annotations were masked by a breast radiologist, and calcifications (calcs) were masked by a computer vision–based algorithm and a deep learning–based U-net segmentation network (step 3). A total of 109 radiomic features and four clinical features were collected (step 4). Models with those extracted features and training data were trained (step 5). Selected models were validated on test data. NPV = negative predictive value, OR = odds ratio, PPV = positive predictive value, ROC = receiver operating characteristic, ROI = region of interest, sens = sensitivity, spec = specificity.

Figure 2:

Study inclusion flowchart of patients with ductal carcinoma in situ (DCIS).

Figure 3:

Mammographic images of patients with biopsy-proven ductal carcinoma in situ (DCIS). (A) A 55-year-old woman (right magnification craniocaudal view) diagnosed with DCIS only; model correctly classified as negative findings. (B) A 64-year-old woman (left magnification mediolateral oblique view) with DCIS at core biopsy but subsequently upstaged to invasive disease; model correctly classified as positive findings. Red and blue polygons show lesions annotated by the radiologist.

Figure 4:

Graph shows receiver operating characteristic (ROC) curves and odds ratios (ORs) of prediction models. Receiver operating characteristic curves are shown for two models: one using radiomic and clinical features (gray) and one using clinical features alone (orange). Both receiver operating characteristic curves are plotted as sensitivity (secondary vertical axis on the right) versus specificity (horizontal axis). Blue dashed line is OR curve, plotted as OR (primary vertical axis on left) versus specificity (horizontal axis). Two operating points are shown with symbols and are described in the text: high-sensitivity active surveillance (purple circle); high-specificity surgical planning for sentinel node biopsy alongside with lesion removal surgery (red circle). AUC = area under receiver operating characteristic curve, NPV = negative predictive value, PPV = positive predictive value, Sens = sensitivity, Spec = specificity.