Here's what I believe leads to a lot of confusion: For most of the 20th century, chemotherapy usually meant small molecules that interfere with cell division, r

Here's what I believe leads to a lot of confusion: For most of the 20th century, chemotherapy usually meant small molecules that interfere with cell division, resulting in cellular death. Even in other mechanisms, it wasn't targeting a weakness specific to cancer, thus had many side-effects. What's so special about Imatinib is it targets a fusion protein that is only present in a specific type of cancer. The target is called the BCR-ABL fusion kinase, because it is literally formed by portions of two genes - BCR, and ABL, on two different chromosomes being fused together when these. This drug is only able to bind that fused version, and hence has no impact on healthy (aka non-cancerous) cells. This was one of the first precision/targeted therapies of its kind. What's super confusing is people eventually started calling these precision therapeutics "chemotherapy" as well, so the previous common-use meaning and layperson associations with the word became mostly muddled. So - to drive the point home, with these targeted therapies, you can have immense benefit with minimal side effects. Not so much with the older stuff, which is also still used in many other types of cancers.