#1: Solid Tumor Rules (2018)
Source 1: 2018 Solid Tumor Rules
Notes: Breast; July 2019 Update
Histology/Behavior--Breast: How are histology and behavior coded for a case originally diagnosed as in situ and later an invasive tumor with a different histology is diagnosed but still a single primary using Breast Solid Tumor Rule M10? See Discussion.
SINQ 20200022 indicates that cases originally diagnosed as in situ do not have a new primary when a new invasive tumor with a different histology is diagnosed within 5 years. Should histology and/or behavior get updated for the in situ breast primary?
Update the histology and behavior based on the invasive tumor when an invasive tumor is diagnosed within 5 years of an in situ tumor in the same breast. This will be updated in the 2021 revisions of the Breast Solid Tumor Rules.