Second primary ipsilateral breast cancer with contralateral axillary involvement: a case report and literature review.

After breast-conserving surgery for an initial breast cancer, the incidence of lymphatic drainage to sites other than the ipsilateral axilla, such as the contralateral axilla, increases significantly at the time of a second primary ipsilateral breast cancer. Given the likelihood of altered lymphatic drainage, and in the absence of distant metastatic sites, consideration should be given to treating patients with a second primary ipsilateral breast cancer and contralateral axillary lymph node involvement with curative intent. This clinical issue may become more common as the incidence of second primary ipsilateral breast cancer would be expected to increase due to widespread adoption of breast-conserving surgery, improved prognosis for patients with an initial early-stage breast cancer, and highly sensitive screening modalities such as magnetic resonance imaging.