SEER Inquiry System - View
Source 1: 2012 SEER Manual
Notes: Section IV
Primary site: What is the single primary site used for a patient with multiple tumors in the duodenum and jejunum? See discussion.
The patient has a tumor in the jejunum and another tumor in the duodenum. Both tumors have the same histology. This disease process is a single primary per Other Sites Rule M18. Is the primary site coded to the more invasive tumor? If the tumors are equally invasive, is the primary site coded to C179?
Code the primary site to C179 [small intestine, NOS] for multiple invasive tumors of the small intestine accessioned as a single primary.
The steps used to arrive at this decision are:
Step 1: Go to the Primary Site subsection located in Section IV of the 2012 SEER Manual titled “Description of This Neoplasm.”
Step 2: Apply instruction 5. “Code the last digit of the primary site code to ‘9’ for single primaries, when multiple tumors arise in different subsites of the same anatomic site and the point of origin cannot be determined.” Code the primary site to C179 [small intestine, NOS].
When multiple tumors arising in different subsites are accessioned as a single primary, the primary site is coded to the NOS code, in this case small intestine, NOS [C179]. The level of invasion does not determine the primary site, unless one or more of the tumors is in situ and another is invasive.