Utility of Ultrasound and Mammography in Detection of Negative Axillary Nodal Metastasis in Breast Cancer

Objective The status of axillary lymph nodes is one of the most important prognostic factors in patients with breast cancer. A precise noninvasive evaluation of axillary lymph node status preoperatively, although challenging, is vital for optimization of the treatment plan for patients. The objective of our study was to assess the utility of ultrasound and mammography in detecting the absence of axillary lymph nodal metastasis in patients of breast cancer, taking histopathology as gold standard. Methods A cross-sectional study was conducted in the Department of Radiology, Aga Khan University Hospital, Karachi. All female patients between 20 and 95 years of age with a known diagnosis of breast cancer with mammographic and ultrasound imaging done at our institute were included. Patients with abnormal lymph nodes on mammography or on ultrasound, patients already operated for breast cancer, patients who already underwent axillary lymph node dissection and those whose histopathology reports were not available or who did not undergo surgery were excluded. Results A total of 262 women with breast carcinoma who had both ultrasound and mammography done and also had surgery performed at our institution were included. At final surgical pathology, a total of 45 of the 262 patients (17.2%) with breast carcinoma had one or more positive lymph nodes. Out of the total 262 patients, 217 patients were found to be true negatives as they had absent axillary nodal metastasis on imaging as well as on histopathology. In all, 45 out of 262 patients were found to be false negatives as they had absent axillary nodal metastasis on imaging; however, they were found to be positive for metastasis on histopathology. The negative predictive value was 82.8%. Patient age was considered as a factor that may influence the outcome of results; the patients were stratified into age ranges seven groups with the age range of 10 years, ranging from 26 to 95 years. Chi-square test showed a p-value of 0.148, which showed no significant difference in the effect of age on diagnosing the absence of metastasis by ultrasound and mammography. Conclusion Our study shows that ultrasound and mammography even when used in combination cannot safely exclude axillary metastasis and thus cannot eliminate the need for sentinel node biopsy.