Prediction of axillary lymph node metastasis in breast cancer using preoperative CT Hounsfield units

Preoperative evaluation of axillary lymph node metastasis is crucial for selecting the optimal perioperative treatment for breast cancer. The most common methods for this evaluation include imaging tests, such as ultrasonography, and pathological assessments. This study investigated the utility of computed tomography (CT) Hounsfield units (HU) in diagnosing axillary lymph node metastasis. This retrospective study examined 218 patients with breast cancer who underwent surgery at our hospital between June 2017 and December 2023. We measured the HU of axillary lymph nodes using preoperative CT scans and defined the highest value as CT-HUmax. We explored the relationship between axillary lymph node CT-HUmax and the presence of metastasis. There were 56 patients in the axillary lymph node metastasis-positive group (P group) and 162 in the axillary lymph node metastasis-negative group (N group). The median CT-HUmax value was 48 (−25–69) for the P group and 30 (−17–73) for the N group, with the former having significantly higher values than those of the latter ( P  < .001). Similar findings were obtained with contrast-enhanced CT (CE-CT). Multivariate analysis revealed that CT-HUmax was a predictive factor for metastasis (odds ratio [OR]: 1.035; 95% confidence interval [CI]: 1.019–1.072; P  = .011). The area under the receiver operating characteristic curve for CT-HUmax was 0.761 (95% CI: 0.688–0.834, P  < .001). The cutoff value for CT-HUmax was 46, while the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy rate using this value were 61%, 84%, 57%, 86%, and 78%, respectively. When CE-CT was used, the cutoff value was 134, and accuracy was 79%. CT-HU may be an effective predictor of axillary lymph node metastasis in breast cancer.