Inclusion Criteria OGA:

1. Voluntary written informed consent of the participant or their legally authorized representative has been obtained prior to any screening procedures.
2. Age 18 or older.
3. New histologic or cytologic proven diagnosis of oesophagogastric adenocarcinoma.
4. Patient underwent a [18F]FDG PET/CT.
5. TNM classification: cT1-4N0-3M0

Inclusion Criteria PDAC:

1. Voluntary written informed consent of the participant or their legally authorized representative has been obtained prior to any screening procedures.
2. Age 18 or older.
3. New histologic or cytologic proven diagnosis of pancreatic ductal adenocarcinoma.
4. Patient underwent a [18F]FDG PET/CT or conventional staging with CT or MRI.
5. TNM classification: cT1-4N0-2M0-1, with the exception of upfront resectable patients.

Inclusion Criteria Clinically challenging cohort:

1. Voluntary written informed consent of the participant or their legally authorized representative has been obtained prior to any screening procedures.
2. Age 18 or older.
3. Histologic or cytologic proven diagnosis of a malignancy.
4. Patient underwent a [18F]FDG PET/CT.
5. Unexplained symptoms, complaints, biochemical or imaging (scintigraphy, PET, CT, MR) findings.

Exclusion Criteria:

1. Participant is mentally or legally incapacitated, doesn't understand the study design or is not willing or capable to undergo all study-specific procedures.
2. Any disorder or condition, which in the Investigator's opinion might jeopardise the participant's safety or compliance with the protocol.
3. Any prior or concomitant treatment(s) that might jeopardise the participant's safety or that would compromise the integrity of the Trial.
4. Female who is pregnant (urinary hCG test can be performed in case of doubt), breast-feeding or intends to become pregnant or is of child-bearing potential and not using an adequate, highly effective contraceptive (with a relatively high Pearl Index: natural methods, minipill outside postpartum period, spermicides or condoms in monotherapy or no usage of contraception when sexually active are not accepted).
5. Participation in an interventional Trial with an investigational medicinal product (IMP) or device when the trial designs are not considered compatible by the study team.
6. Participation in a clinical scientific study in the last 12 months with a radiation exposure caused by the experimental procedures greater than 1 mSv.
7. Participant has a known hypersensitivity to [18F]AlF-FAPI-74 or the used excipients.

History of severe allergic reactions to study medication Currently pregnant or breastfeeding Recent participation in another clinical trial within the last 30 days Presence of uncontrolled medical conditions that could affect safety