FOLH1 and cancer: As the development of various tracers such as 68Ga-prostate-specific membrane antigen (PSMA) has had a considerable impact on radiation oncology and current oncological guidelines, especially in combination with concepts such as oligometastases that have increased the importance of determining the exact spread of a patient’s cancer, herein, we conducted a systematic review of the available data regarding FAP-specific PET and focus on its potential use for radiotherapy treatment planning [9,10].