F-Tryptophan PET/CT in Human Cancers

This study is testing a new type of PET scan that uses a radioactive form of tryptophan (an amino acid) to detect and better characterize various types of cancer, including brain tumors, breast cancer, and neuroendocrine tumors. The scan may help doctors see tumors that are hard to detect with other imaging. **You may be eligible if:** - You are 18 or older - You have a tumor that is at least 1 cm in diameter visible on existing imaging - You can lie still in a PET scanner for about 70 minutes - You are not pregnant or breastfeeding - You have had recent conventional imaging showing visible disease - Specific eligibility also depends on your cancer type (brain tumor, neuroendocrine tumor, or breast cancer) **You may NOT be eligible if:** - You are pregnant or breastfeeding - Your tumor is too small to be detected - You cannot tolerate lying still for the scan Talk to your doctor to see if this trial is right for you.