6. History or clinical evidence of central nervous system (CNS) metastases or leptomeningeal carcinomatosis, except for individuals who have previously treated parenchymal CNS metastases, are asymptomatic, and have had no requirement for steroids or anticonvulsants for >2 months prior to study enrollment. Routine screening with CNS imaging studies (computed tomography [CT] or magnetic resonance imaging [MRI]) is required only if clinically indicated, or if the patient has a history of CNS metastases.