Patients with breast cancer are increasingly likely to have chest computed tomography (CT) performed. In many cases, small lung nodules will be detected, raising concern for metastases and causing considerable patient anxiety. The majority of these nodules, however, are benign, though the specific probability of malignancy is uncertain in any given case. Therefore, we analyzed the results of chest CT scans of a large number of patients with breast cancer, to determine characteristics and clinical significance of noncalcified lung nodules. 3313 patients were investigated, and 4889 CT scans from 1325 patients were retrospectively reviewed. Among the 1325 patients, 812 (59 %) had at least one noncalcified lung nodule, of which 330 (41 %) had malignant nodules, 197 (24 %) had large (≥10 mm) nodules, and 586 (72 %) had multiple nodules. Large nodules were more often malignant than benign (P < 0.001). In patients with multiple large nodules, the rate of malignancy rate was 83 %, and most of these were metastases. In the case of very small (2-4 mm) nodules, the malignancy rates for solitary and multiple nodules were 8 and 20 %, respectively. Lung metastases were more likely with breast cancer cell grade 3 (22 %) than grade 1-2 (10 %) (P < 0.001) and when patients were clinical stage 2-3 (14 %) than stage 0-1 (7.9 %) (P = 0.03). Lung metastases are highly likely in patients with multiple nodules greater than 10 mm. Higher cancer cell grades and clinical stage are also related to an increased likelihood of lung metastases. The great majority of small lung nodules in breast cancer patients are benign.
Keywords: Breast cancer; Chest CT; Lung metastases; Lung nodule; Malignant or benign.