Thanks for your question on Health Care Magic.
I can understand your friend's situation and problem.
Prostate cancer is known to spread in bones, liver, lung, brain etc.
So possible future complications are bone pain, fractures, cough,
hemoptysis (blood in sputum), breathlessness, jaundice, abdominal distention etc.
And his behavioural changes like
depression, feeling of death etc are known as malignancy associated psychosis. Cancer is having huge impact on patient 's psychology. Since cancer is incurable with all the available treatment, patient can easily go in depression and psychosis.
Your friend is also having the same symptoms.
So better to
consult psychiatrist and get done counseling sessions. He needs
psychotherapy and discussion on end of life issues.
This will be of great help to him.
Hope I have solved your query. Wishing good health to your friend. Thanks.