This study is testing two medicines to help cancer patients with appetite loss. It compares olanzapine, a drug that might help increase appetite and prevent weight loss, with megestrol acetate, the usual treatment. Patients will be randomly assigned to take either olanzapine or megestrol acetate once a day for up to four weeks.

Key Points:

• The study lasts up to 4 weeks, and involves taking medicine daily.
• Participants must be 18 or older, with advanced cancer and problems with appetite or weight loss.
• Women and men must agree to use birth control, as the drugs might affect unborn babies.

To join, participants need to have lost at least 5 pounds in the last two months or have a low calorie intake. They should not be using certain other appetite medicines, have a history of blood clots, or have serious infections. This study aims to find out if olanzapine works better than megestrol acetate for improving appetite. Participants should not have uncontrolled diabetes, be pregnant, or have a history of poorly controlled hypertension.