Fig. 2.

Participants in the metastasis and vaccine groups. Among 684 axillae (342 patients), 96 were excluded for the following reasons: simultaneous bilateral breast cancer, no preoperative MRI, uncertain vaccination date, uncertain upper extremity vaccination site, and vaccination in both upper extremities. Among the remaining 588 axillae, 22 axillae of patients who were vaccinated and had lymph node metastasis were excluded. We also excluded 417 axillae of patients who were not vaccinated and did not have lymph node metastasis. Of the 74 axillae of patients who were vaccinated and did not have lymph node metastasis, 33 with no lymphadenopathy were excluded. On the other hand, among the 75 axillae of patients who were not vaccinated and had lymph node metastasis, 36 axillae with no lymphadenopathy were excluded. Finally, 41 axillae were included in the vaccine group, and 39 were included in the metastasis group. MRI magnetic resonance imaging