Due to a misunderstanding.
Initially, the malignant tumors that attracted the attention of doctors were skin tumors. They were described by ancient physicians. Many of these formations have a smooth and relatively dense surface of a pinkish hue, resembling a crab's shell.
These neoplasms received the Latin name *cancer*, which translates to "crab." However, this is also the Latin term for a freshwater crayfish, and during the translation from Latin to Russian, this word became established.
