PET/CT Imaging of GRPR Expression in Various Tumors

Inclusion Criteria: Age 18 years or older Able to understand and provide written informed consent Diagnosis of a breast cancer or other tumor known or suspected to express GRPR, including: ER-positive/HER2-negative breast cancer Invasive lobular breast cancer Head and neck squamous cell carcinoma Small-cell lung cancer Ovarian cancer Prostate cancer with biochemical recurrence and a negative PSMA PET/CT Metastatic pancreatic cancer after pancreatic surgery Other tumor with GRPR expression demonstrated on histopathology ECOG performance status 0-3 Under the care of a referring physician Able to tolerate PET/CT imaging, including lying supine for up to 30 minutes with arms above the head and intravenous cannulation Exclusion Criteria: Tumor type known in the literature not to express GRPR, unless patient-specific tissue demonstrates GRPR expression Medically unstable condition, including acute cardiac or respiratory distress or hypotension Weight exceeding PET/CT table limit of 200 kg or inability to fit within the 70-cm PET/CT bore Unmanageable claustrophobia Known allergic or hypersensitivity reaction to a prior GRPR-targeting radioligand such as ⁶⁸Ga-RM2 or bombesin analogues Pregnancy Lactation For individuals of childbearing potential, inability to document a negative pregnancy test before tracer administration