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SEER Inquiry System - Report
Produced: 01/18/2026 3:36 AM
Question 20210068
Inquiry Details
References:
2021 SEER Manual, 134-145. Mets at Diagnosis data items
Question:
Mets at Diagnosis Fields/Primary Site--Lymph Nodes: How are the Mets at Diagnosis fields coded when the metastatic adenocarcinoma involves only one lymph node area and the primary site is unknown? See Discussion.
Discussion:
In 2018, patient has lymph node metastasis confined to left retroperitoneal area; core biopsy was done which showed metastatic adenocarcinoma, unknown primary site. There are no other sites of disease found. Should I code Mets at Diagnosis--Distant Lymph Node(s) as 1, and the others such as bone and lung as 0?
Answer:
In a situation like this with one area of metastatic involvement and an unknown primary, if there is no further information, we advise that the metastasis are "regional" until/unless proven otherwise. With this in mind, code the Mets at Diagnosis fields as 0, including the Mets at Diagnosis--Distant Lymph Node(s). This case should continue to be worked up to identify the primary site. If a primary site is identified later, update the abstract accordingly. In the meantime, use text fields to describe the situation.
