Ultrasonographic detection of occult cancer in patients after surgical therapy for breast cancer

Objective. The purpose of this study was to investigate the efficacy of ultrasonography in detecting an occult malignancy after surgery for breast cancer and to assess the imaging and clinical findings associated with a recurrence. Methods. During a 4-year period, 3329 bilateral whole-breast ultrasonographic examinations were performed to detect occult malignancies clinically and mammographically in 1968 asymptomatic patients after breast cancer surgery. All questionable lesions were confirmed with ultrasonographically guided intervention. This study reviewed ultrasonographic findings and pathologic results of the questionable lesions along with the clinical parameters of the patients. We searched for false-negative cases from the hospital database. Results. Among the 1968 patients, ultrasonography revealed questionable lesions in 57 (2.9%). The questionable lesions were lymph nodes in 42 and masses in 15; of these lesions, 24 were malignant (true-positive) and 33 were benign (false-positive). Ten false-negative cases were identified. The sensitivity and specificity were 70.6% and 98.3%, respectively. The locations of the recurrent lesions were the regional lymph nodes in 14 cases (4, axillary fossa; 4, interpectoral; 4, internal mammary; and 2, supraclavicular lymph nodes) and the breast and mastectomy bed in 7 cases. The mean size of the malignant lymph nodes was larger than that of the benign lymph nodes. Among those with positive examination results, the clinical parameters in the recurrent and nonrecurrent groups were similar. Conclusions. Postoperative follow-up ultrasonography showed occult malignancies clinically and mammographically in 1.2% of the patients who had been treated for breast cancer. Familiarity with the common location of a tumor recurrence is essential for making an accurate ultrasonographic evaluation in these patients.