Given similar concordance in bladder cancer [9] as well as the fact that Her2/neu expression is more common in bladder cancer than in breast cancer [5], it remains to be seen if the incidence of carcinomatous meningitis due to leptomeningeal bladder metastases will increase in the setting of trastuzumab therapy as a consequence of systemic therapeutic efficacy and poor CNS bioavailability. The gene discussed is ERBB2; the disease is urinary bladder carcinoma.