SEER Training Modules

Coding CS Tumor Extension

CS Extension identifies contiguous growth of the primary tumor within the organ or direct extension into neighboring organs. For two sites, ovary and corpus uteri, discontinuous metastasis is coded in the CS extension field. Site-specific schemes contain detailed codes and coding instructions.

CS Tumor Extension allows the data to be collapsed into the AJCC T component and Stage Group, Summary Stage 1977, and Summary Stage 2000 (localized or regional direct extension), and provides flexibility for consistency over time.

See the slide that shows an example of coding tumor extension.

View the General Rules for Coding Tumor Extension.