Chemo and radiation

Claim: For a leukemia that has already spread throughout the bloodstream, a targeted therapy that flags one specific molecule on the cancer cells is usually a better fit than broad chemotherapy.\nEvidence 1: A targeted therapy is built to recognize a protein that appears mainly on the cancer cells, so it binds those cells and triggers apoptosis (programmed cell death) while mostly leaving normal cells alone, which concentrates the killing on the diseased cells even though they are scattered everywhere.\nEvidence 2: Broad chemotherapy travels through the whole body and kills any fast-dividing cell, so it does reach cancer cells no matter where they are, but it also damages healthy fast-dividing tissue and causes side effects like hair loss, mouth sores, nausea, and low blood counts, because hair follicles, the gut lining, and bone marrow all divide quickly.\nReasoning: When the cancer is spread out in the blood, the treatment has to reach the whole body, so a local option would miss most of the disease. Both a targeted therapy and broad chemotherapy can reach cells everywhere, but the targeted drug aims at a marker that is far more common on the cancer cells, so it spares more healthy tissue and tends to cause milder side effects than chemotherapy, which hits every fast-dividing cell it passes. Because the reach of each treatment has to match how spread out the disease is, and because that reach is what decides which healthy tissues get harmed, the targeted therapy fits this widespread situation better.