We wanted to evaluate the sonographic findings of recurrent breast cancer in the patients who underwent mastectomy or breast conserving surgery (BCS). We also wanted to evaluate the characteristics of recurrent cancer that's detected on follow up sonography only.

We retrospectively reviewed 87 patients with recurrent breast cancer and who were operated on during the previous 10 years. We analyzed the method of detection and the sonographic appearance of tumor, including the location, size, shape, margin, internal echogenicity and BI-RADS categories, in 52 patients who had abnormal sonographic findings. We compared the sonographic findings of the recurrent cancer between the patients who underwent mastectomy and the patients who underwent BCS. We also analyzed the characters of the recurrent cancer that was only detectable on follow-up sonography.

Among the 87 patients with recurrent breast cancer, 37 patients had undergone previous mastectomy and 50 patients had undergone previous BCS. The most common mode of detection was a palpable mass on physical examination for the patients who underwent mastectomy (64.9%, 24/37) and the most common mode of detection was the follow-up sonography for the patients who underwent BCS (40%, 20/50). The sonographic appearance of the recurrent cancer was similar for both the patients who underwent mastectomy or BCS. The most common locations were the breast parenchymal layer in 82% (36/44) of the patients who underwent BCS and the subcutaneous fat layer of the operated area in 67% (14/21) of the patients who underwent mastectomy. The type of recurrent cancer detected on sonography only was small nodules in the patients who underwent BCS, and that for the patients who underwent mastectomy was nodules, regardless of size, that were located in the deep muscle layer.

Recurrent breast cancer, regardless of size, was frequently detected on a physical examination in the patients who underwent previous mastectomy, and this was detected on sonography in the patients who underwent with previous BCS. Follow up sonography was valuable to evaluate for tumor recurrence after breast cancer surgery, and this detected 16% (6/37), 28% (14/50) of the recurrent cancers that were otherwise occult tumor.