Which term is synonymous with 'localized' when discussing tumors?

The term that is synonymous with 'localized' when discussing tumors is 'in situ.' This term specifically refers to cancer that is confined to the original site where it formed, without spreading to surrounding tissues or distant parts of the body. In situ tumors are often considered non-invasive because they have not yet breached the basement membrane of the tissue, meaning they remain in a localized state.

In contrast, the other terms such as invasive, actively spreading, and malignant refer to characteristics of tumors that suggest either growth into surrounding tissues, a tendency to metastasize (spread), or the aggressive nature of certain cancers. These terms describe processes that involve movement beyond the original tumor site, which contrasts with the localized nature of in situ tumors.