cancer has 4 distinct synonyms spread across 4 of its 5 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
any malignant growth or tumor caused by abnormal and uncontrolled cell division; it may spread to other parts of the body through the lymphatic system or the blood stream
a small zodiacal constellation in the northern hemisphere; between Leo and Gemini
the fourth sign of the zodiac; the sun is in this sign from about June 21 to July 22
Synonyms, antonyms and the broader and narrower relations for cancer come from Princeton University’s WordNet. Full sources and licences.