UZ/KU Leuven Program for Post-mortem Tissue Donation to Enhance Research

Inclusion Criteria: * Age ≥ 18 years. * Signature of informed consent by the subject. * Metastatic breast cancer, or hereditary cancer syndrome with a moderate to high lifetime risk of breast cancer, for which the patient is treated/followed in UZ Leuven or treated in another hospital and referred to UZ Leuven specifically for the trial. Additional inclusion criteria for the different substudies: * Pilot phase: no additional inclusion criteria. * ILC substudy: histologically confirmed history of ILC. * IBC substudy: history of IBC, fulfilling the following criteria described by Dawood et al: rapid onset of breast erythema, oedema and/or peau d'orange and/or warm breast with or without an underlying palpable mass, duration of history of no more than 6 months, erythema occupying at least one-third of the breast and pathological confirmation of invasive carcinoma. * Hereditary cancer syndrome substudy: confirmed presence of a germline mutation known to be associated with a moderate to high lifetime risk of BC (e.g. known pathogenic variants in the genes BRCA1/2, CHEK2, TP53, PALB2) and presence of at least one malignant lesion at time of inclusion (of any origin) . * Other substudies: no additional inclusion criteria. Exclusion Criteria: * Presence of a transmissible disease that can form a risk to the health of researchers or others handling the body or patient samples. This includes but is not limited to the following infectious diseases: human immunodeficiency virus (HIV), active hepatitis C virus (HCV), encephalitis of unknown cause, Creutzfeldt-Jakob disease, rabies, active malaria, active tuberculosis, active SARS-CoV-2 infection. * Presence of any factors that could logistically or organizationally impede the study or the performance of sampling within a reasonable post-mortem time frame. This includes but is not limited to: residence of the subject at a faraway distance from the UZ Leuven hospital; residence of the subject on territory outside of Belgium; impossibility to notify the clinician confirming the death and the researchers within a reasonable time frame in case of death. Additional exclusion criteria for the different substudies: \- ILC substudy, IBC substudy: diagnosis of a malignancy other than breast cancer in the 5 years prior to inclusion. Exceptions include basal cell carcinoma of the skin or squamous cell carcinoma of the skin and in situ cervical carcinoma.