canceryoudaoicibaDictYouDict[cancer 词源字典]
cancer: [14] Cancer comes from Latin cancer, which meant literally ‘crab’. It was a translation of Greek karkínos ‘crab’, which, together with its derivative karkínōma (source of English carcinoma [18]) was, according to the ancient Greek physician Galen, applied to tumours on account of the crablike pattern formed by the distended blood vessels around the affected part.

Until the 17th century, the term generally used for the condition in English was canker, which arose from an earlier borrowing of Latin cancer in Old English times; before then, cancer had been used exclusively in the astrological sense. The French derivative of Latin cancer, chancre, was borrowed into English in the 16th century for ‘syphilitic ulcer’.
=> canker, carcinoma[cancer etymology, cancer origin, 英语词源]
cancer (n.)youdaoicibaDictYouDict
Old English cancer "spreading sore, cancer" (also canceradl), from Latin cancer "a crab," later, "malignant tumor," from Greek karkinos, which, like the Modern English word, has three meanings: crab, tumor, and the zodiac constellation (late Old English), from PIE root *qarq- "to be hard" (like the shell of a crab); cognates: Sanskrit karkatah "crab," karkarah "hard;" and perhaps cognate with PIE root *qar-tu- "hard, strong," source of English hard.

Greek physicians Hippocrates and Galen, among others, noted similarity of crabs to some tumors with swollen veins. Meaning "person born under the zodiac sign of Cancer" is from 1894. The sun being in Cancer at the summer solstice, the constellation had association in Latin writers with the south and with summer heat. Cancer stick "cigarette" is from 1959.