Relapsed blood cancer occurs when leukemia, lymphoma, or myeloma returns after initial remission, requiring specialized treatment pathways that differ fundamentally from first-line therapy based on disease biology, prior treatment response, transplant eligibility, and overall fitness. TL;DR Treatment resistance affects 30-40% of blood cancer patients, but salvage chemotherapy, targeted therapy, immunotherapy, stem cell transplant, and CAR-T therapy provide established pathway