Cancer, the Crayfish, and the Crab
I am fascinated with word origins. Reading a cancer research newsletter recently motivated me to do a little digging to find the origin of the word "cancer".
The world's oldest documented case of the disease we now call cancer was recorded on papyrus in ancient Egypt around 1500 BC. Later, the Greek physician Hippocrates was the first to describe cancer using the Greek word karkinos which means crayfish or crab. He chose this word because the blood vessels that surrounded tumors resembled the shape of a crab. Hippocrates believed that an excess of "black bile" (one of the "four fluids") in any given site in the body caused cancer. Later, the Roman physician and encyclopedist Aulus Cornelius Celsus (c. 25 BC - c. 50 AD) translated the Greek word into the Latin word "cancer". From this we also get the word "carcinoma" (from Gk. karkinos, crab and -oma, growth), and "carcinogenic" (an agent which causes cancer).
The astrological sign Cancer is symbolized by a crab. Cancer was also sometimes called Carcinos, another Latinized version of karkinos. In Greek mythology, the godess Hera placed the figure of a crab in the nighttime sky to honor it after the crab was killed by Heracles during a battle with Hydra. Other variations of the story say that Hercules kicked Cancer so hard that the crab was sent into the sky. I have read that the Egyptians saw the constellation we now call Cancer as the sacred scarab, a beetle which lays its eggs in pellets made from its own dung. From this observed behavior, the Egyptians saw the scarab as a symbol of resurrection and immortality. The Greek word for scarab is karabos which is curiously similar to the Greek karkinos. Both the beetle and the crab have hard shells on the outside and are soft and vulnerable on the inside. For this reason, those born under Cancer are described as being extremely protective of a vulnerable underside. They may appear tough and impenetrable on the outside but be caring and sensitive on the inside. They also make great cakes.