instruction: tell me the time when patient 005-87465 was first diagnosed with brain tumor since 4 years ago?
response: SELECT diagnosis.diagnosistime FROM diagnosis WHERE diagnosis.patientunitstayid IN (SELECT patient.patientunitstayid FROM patient WHERE patient.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.uniquepid = '005-87465')) AND diagnosis.diagnosisname = 'brain tumor' AND DATETIME(diagnosis.diagnosistime) >= DATETIME(CURRENT_TIME(), '-4 year') ORDER BY diagnosis.diagnosistime LIMIT 1