Metastasis is the major cause of death from cancer. Metastasis to the lymph node (“regional” metastasis) generally precedes distant metastasis, and we recently demonstrated that metastasis to the lymph nodes is a likely prerequisite for metastasis to the central nervous system (CNS) in humans with breast cancer (1-8). Here we utilize whole transcriptome technologies (9, 10) to measure total transcription in the primary tumor and in the lymph node metastases of humans with breast cancer to define the lymph node metastatic transcriptome. We identify here a therapeutic target based on its differential expression and up-regulation upon metastasis to the lymph nodes in humans with breast cancer, ADCY9, as a candidate therapeutic target for the medical management of lymph node metastasis.