#2: Summary Stage 2018
Source 1: Summary Stage 2018 Coding Manual v2.0
Notes: September 2020
Source 2: AJCC Cancer Staging Manual
Notes: 8th edition
Behavior/Summary Stage 2018--Colon: What is the correct behavior and Summary Stage for a case of intramucosal adenocarcinoma arising in tubular adenoma? AJCC states this is Tis, though SEER Summary Stagie states this is Localized (code 1). The histology is 8140/2 (adenocarcinoma in situ), but the SEER Summary Stage is Locallized.
Intramucosal carcinoma of the colon is assigned behavior code of /3. Intramucosal is not the same as in situ in terms of behavior. Behavior and staging are separate concepts, although there is some overlap. Use the instructions for coding behavior to code this field. Do not use stage to determine behavior in this case.
For purposes of Summary Stage, intramucosal carcinoma is a localized lesion; however, for purposes of AJCC staging, assign Tis for the stage.