Multimodal Imaging With FAPI-PET/MRI in Breast Carcinoma-In-Situ for Detection of Occult Invasive Cancer

Ductal carcinoma in situ (DCIS) is a common precursor to breast cancer where abnormal cells are present within the milk ducts without breaking through their walls (in situ). If these cancerous cells have already breached the boundaries of the milk ducts, it is referred to as "invasive carcinoma." About half of these precancerous conditions develop further into invasive carcinomas over time. However, since doctors cannot precisely predict this at an individual level, treating DCIS often involves removing the affected tissue to prevent progression towards invasive cancer. Typically, diagnosis relies on performing a biopsy, during which cells from the altered tissue are extracted and examined under a microscope. Unfortunately, determining whether or not an invasive carcinoma has developed is not always possible with certainty with this method; indeed, about one quarter of cases involving existing invasive carcinomas might remain undetected by conventional biopsy procedures.

Consequently, being able to ascertain before surgery if an invasive carcinoma exists or not would be highly beneficial. This study examines a novel method that could potentially enhance the discovery of hidden (also called 'occult') invasive carcinomas. Specifically, it employs positron emission tomography (PET) utilizing a radiopharmaceutical agent known as [68Ga]Ga-FAPI-46. This compound selectively targets and binds to fibroblast activation protein (FAP), abundant on surfaces of tumor-associated fibroblasts. By tagging this structure with a radiotracer, researchers aim to achieve precise visualization and assessment of tumor extent. For the PET examination, a minimal dose of the radiopharmaceutical is administered intravenously while sensitive cameras capture images of particular body sections externally (PET). Additionally, magnetic resonance imaging (MRI) of the breast is conducted concurrently to ensure anatomical orientation, image enhancement (attenuation correction), and additional information acquisition.

The trial visits will be scheduled during the regular treatment process. These will not extend the participant's overall treatment duration significantly, as all measures within the scope of the study typically occur within 30 days, but no more than 51 days. During this period, effective contraception is necessary.

Researchers will then compare the imaging results to the pathology ground truth to evaluate the feasibility of the method.