You don't have to be admitted to a hospital for cancer. It can be treated in the outpatient now.
Cancer doesn't require hospitalization. It can be treated in the outpatient setting nowadays.
「癌で入院する必要はなく、外来で治療できます」のように説明的に表すのが自然かと思いました。
入院する＝is admitted to a hospital, is hospitalized
入院＝admission to the hospital, hospitalization
外来＝outpatient
癌治療の外来クリニック＝cancer outpatient clinic
日本 
