noun which may take the genitive case particle 'no'
untreatable; incurable
Medical term used for diseases or conditions that cannot be treated or cured. Often used in formal or clinical contexts.
He was diagnosed with an incurable disease.
This cancer has progressed to an untreatable stage.
不治 is a more literary or formal term for 'incurable', often used in set phrases like 不治の病. 治療不能 is more clinical and directly states that treatment is impossible.
難治 means 'intractable' or 'difficult to treat', implying treatment is possible but challenging. 治療不能 means treatment is not possible at all.
Compound of 治療 (treatment) + 不能 (impossible). The word follows standard Sino-Japanese word formation patterns.