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SEER Inquiry System - Report
Produced: 05/09/2026 5:30 PM
Question 20230031
Inquiry Details
References:
Solid Tumor Rules. Lung, September 2021 Update
Question:
Solid Tumor Rules/Multiple Primaries--Lung: How many primaries and what M Rule applies to a 2022 diagnosis of right upper lobe non-small cell lung carcinoma (NSCLC) when the patient has a history acinar adenocarcinoma in the right lower lobe of the lung in 2020, followed by squamous cell carcinoma in the right middle lobe of the lung in 2021? See Discussion.
Discussion:
The patient was not synchronously diagnosed with multiple tumors, but three separate tumors with three different histologies were diagnosed at different times and no more specific histology was provided for the NSCLC. The timing rules do not apply to this case (the tumors were not greater than 3 years apart and they were not synchronously/simultaneously diagnosed).
While NSCLC is a NOS histology for both adenocarcinoma and squamous cell carcinoma, it is unclear if Rule M8 should apply because NSCLC is not listed in Table 3 (Table 3 is not an exhaustive list). In some situations, Rule M8 would apply if the tumors were different histologies and one of the histologies was not listed in the Table. Does that logic still apply if one of the tumors is NSCLC? If NSCLC is excluded from Rule M8, is Rule M14 the appropriate M Rule for the 2022 NSCLC diagnosis?
Answer:
The patient's previous acinar adenocarcinoma in the right lower lobe of the lung in 2020 and squamous cell carcinoma in the right middle lobe of the lung in 2021 were correctly abstracted as two primaries per rule M8 as they are in different rows in Table 3. The NSCLC, RUL (8046) diagnosed in 2022 would not be abstracted as a third primary because NSCLC is a broad category which includes all histologies in Table 3 (except for small cell carcinoma/neuroendocrine tumors (NET Tumors) 8041 and all subtypes), and because it was diagnosed less than 3 years after the 2021 squamous cell carcinoma, RML (8070).
