Radiologists Detect A Higher Frequency of Incidental Findings On Radiotherapy-Planning CT Scans of Breast Cancer Patients Than Oncologist

Purpose: Breast cancer patients scheduled for postoperative radiotherapy undergo radiotherapy-planning computed tomography (CT), and incidental findings (IFs) may appear. This study investigated the interobserver variability between radiologists and oncologists when assessing IFs on radiotherapy-planning CT scans in breast cancer patients prior to adjuvant radiotherapy. Methods: We included 383 breast cancer patients who underwent planning CT at the Aalborg University Hospital between February 1, 2017 and February 28, 2018. IFs noted by the oncologists were identified from medical records. Two specialized radiologists reviewed the scans and described their IFs. IFs were classified as benign or potential malignant lesions. Cohen’s kappa statistic was used to measure interobserver agreement.Results: A total of 513 IFs were registered. The radiologists registered 433 findings, and the oncologists noted 80 (1.1 and 0.2 IFs per patient, respectively). Most potential malignant IFs were found in the liver, lungs, bones, and lymph nodes. The radiologists and oncologists detected potential malignant lesions in 94 (25%) and 34 (9%) patients, respectively. The oncologists’ sensitivity for detecting IFs in the liver and lungs were 29% and 20%, respectively. The agreements on IFs in the liver and lungs were fair (Cohen’s kappa values of 0.33 and 0.28, respectively).Conclusion: Radiologists reported a significantly higher frequency of IFs and potential malignant lesions than oncologists. Additionally, the oncologists had a low sensitivity when reporting IFs in both the liver and lungs. These results emphasize the need for specialized radiologists to scrutinize planning CT scans of breast cancer patients to ensure the intention to treat.