The Metastatic Rate of Internal Mammary Lymph Nodes When Metastasis of Internal Mammary Lymph Node Is Suspected on PET/CT

PURPOSE Metastatic status of internal mammary lymph node (IMLN) has a clinical importance in assessing the stage and prognosis of breast cancer. But, when metastasis of IMLN is suspected; the management is controversial. We retrospectively reviewed 36 breast cancer patients who underwent IMLN biopsy, and investigated the pathologic status of IMLN which suspected metastasis with positron emission tomography and computed tomography (PET/CT). METHODS From January 2007 to December 2012, 36 patients underwent IMLN biopsy for suspected IMLN metastasis on PET/CT, when diagnosed with primary or recurrent breast cancer. Clinicopathologic features of these patients and metastatic status of IMLNs were investigated. RESULTS A total of 36 patients were included in this study. Twenty-four patients diagnosed with primary breast cancer and 12 patients diagnosed with recurrent breast cancer underwent IMLN biopsy. The mean number of IMLNs was 2.72±2.05, and the total metastatic rate of IMLNs was 72.2% (26 out of 36). IMLN metastasis was confirmed on pathologic examination in 19 patients (79.2%, 19 out of 24) with primary breast cancer and in 7 patients (58.3%, 7 out of 12) with recurrent breast cancer. The mean standardized uptake values of metastatic and nonmetastatic IMLNs in primary breast cancer were 3.50±2.51 and 3.72±3.55, respectively and those of metastatic and nonmetastatic IMLN in recurrent breast cancer were 3.92±2.67 and 4.12±3.57, respectively. In both groups, there was no statistically significant difference between the SUVs of metastatic and nonmetastatic IMLNs (p=0.291 and p=0.951, respectively). CONCLUSION Due to the recent advances in diagnostic and surgical skills, IMLN biopsy can be performed safely without any complications without performing radical mastectomy. If IMLN metastasis is suspected on PET/CT, IMLN biopsy is useful to assess the exact stage and to determine the treatment for breast cancer. Further follow-up studies are needed to assess the locoregional recurrence and to compare the improvement in overall survival and disease-free survival.