Background: Approximately 8–56% of patients with a core needle biopsy (CNB) diagnosis of ductal carcinoma in situ (DCIS) will be upstaged to invasive disease at the time of excision. Patients with invasive disease are recommended to undergo axillary nodal staging, most often requiring a second operation. We developed and validated a nomogram to preoperatively predict percentage of risk for upstaging to invasive cancer. Methods: We reviewed 834 cases of DCIS on CNB between January 2004 and October 2014. Multivariable analysis was used to evaluate CNB and imaging factors to develop a nomogram to predict the risk of upstaging from DCIS to invasive cancer. This nomogram was validated with an external dataset of 579 similar patients between November 1998 and September 2016. An area under the receiver operating characteristic curve was constructed to evaluate nomogram discrimination. Results: The rate of upstaging to invasive disease was 118/834 (14.1%). On multivariable analysis, grade on CNB and imaging factors, including mass lesion, multicentric disease, and largest linear dimension, were associated with upstage to invasive disease, and was used to develop a nomogram (c-statistic 0.71). In the external validation dataset, 62/579 (10.7%) patients were upstaged to invasive disease. Our nomogram was validated in this dataset with a c-statistic of 0.71. Conclusion: For patients with a CNB diagnosis of DCIS, our validated nomogram using DCIS grade on biopsy, and imaging factors of mass lesion, multicentric disease, and largest linear dimension, may be used for preoperative assessment of risk of upstaging to invasive disease, allowing patient counseling regarding axillary staging at the time of definitive surgery.
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