Aims:
The purposes of this study are to explore the prevalence of delirium, to consider clinical factors which are useful to identify at risk patients for delirium with advanced cancer and to investigate the course of delirium in two weeks after admission.

Methods:
Patients aged sixty-five or older with lung malignancy or gastroenterological cancer were continuously sampled when admitted to the university hospital. Patients were made delirium diagnosis based on DSM-IV-TR by psychiatrists and assessed using the Delirium Rating Scale-Revised-98 (DRS-R98) within four days of admission and about two weeks later. And we used ad hoc questionnaire regarding several additional common delirium-related factors. This study was approved by the Institutional Review Board and written informed consent was obtained from each patient.

Results:
Among eligible seventy-three patients, complete data were available from fifty-eight patients on admission and from forty-six patients two weeks later. The mean ± SD and median age　on admission were 72.4 ± 6.5 and 73 respectively. The original cancer sites are lung (74%) and digestive organ (24%). Twenty-six patients (45%) met DSM-IV-TR delirium criteria on admission. Patients with prescriptions of steroid were more vulnerable to delirium just after admission (odds ratio: 4.87, 95% confidence interval: 1.55-15.3). Of forty-six patients, twenty-six patients　(57%) were diagnosed with delirium in two weeks after admission. Of twenty-one patients, nineteen patients (90%) continued to be delirious and of twenty-five patients, eighteen patients (72%) stayed without delirium for about two weeks after admission.

Conclusions:
Advanced cancer patients had high frequencies of delirium on admission. Oncologist may especially pay attention to the patients who use steroids on admission. The intervention which contains a screening for delirium on admission may be useful for advanced cancer patients.