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SEER Inquiry System - Report
Produced: 05/07/2026 7:11 PM
Question 20210012
Inquiry Details
References:
Solid Tumor Rules. Lung; December 2020 Update
Question:
Solid Tumor Rules (2018, 2021/Multiple Primaries/)--Lung: How many primaries should be reported and what M rule applies when a diagnosis of presumed adenocarcinoma in situ (AIS) of the left lung follows a known diagnosis of progressive multifocal malignant adenocarcinoma in the right lung? See Discussion.
Discussion:
Patient was initially diagnosed with a right lower lobe (RLL) lung adenocarcinoma in 2014 followed by subsequent right upper lobe (RUL) lung adenocarcinoma in 2016 (single primary). Both were treated with radiation and the nodules were seen as stable on surveillance. There was subsequent growth in the RUL nodule in 2019 and RLL nodule in 2020 as well as a new right middle lobe (RML) nodule in 2020. All left sided nodules were noted to be stable and/or ground glass opacities.
There was no documented diagnosis of malignancy in the left lung until June 2020 when the physician noted that if there was a response in the left lung to systemic treatment, then this was probably multifocal AIS. However, only one tumor in the left lung responded to treatment.
While it seems somewhat unlikely that only a single AIS in the contralateral lung should be metastasis from the right lung malignancy, it is difficult to apply the multiple tumors rules to this case.
Answer:
Abstract a single primary using 2018 Lung Solid Tumor Rule M9.
The 2014 and 2016 R lung tumors were pathologically confirmed; it is not stated if they were resected. Follow up after XRT noted stable disease but no indication of NED. Subsequent right lung tumor is also the same primary. The issue is the assumed left lung adenocarcinoma in situ. It is not clear how long the left lung nodules were present, but they appeared to be stable as well and only diagnosed as a malignancy based on treatment response. At this time M9 applies and the left lung AIS is not a separate primary. We have discussed at length with lung pathology experts the issue of determining multiple primaries. Identifying and diagnosing lung tumors has become easier with new technology and the result is patients are being diagnosed with multiple lung tumors. Some lung experts feel we are under-reporting lung primaries but all noted the many issues with creating rules for consistency.
