#1: Solid Tumor Rules (2018)
#2: Multiple primaries
Source 1: 2018 Solid Tumor Rules
Notes: Lung, July 2019 Update
Solid Tumor Rules (2018)/Multiple primaries--Lung: How many primaries are there and what M rules apply for multiple lung histologies in the left lower lobe (LLL) and right upper lobe (RUL) of the lungs? See Discussion.
There is one tumor in the left lung that is acinar adenocarcinoma, 8551/3, and two tumors in the right lung, one of which is 8551/3 and a separate one that is mucinous adenocarcinoma 8253/3.
3/21/18- left robotic video assisted thoracoscopy with left lower lobe lobectomy: 2.5 cm adenocarcinoma, acinar predominant, margins negative
11/3/18- right upper lobe lobectomy: invasive mucinous adenocarcinoma, 1.7 cm, invasive adenocarcinoma, acinar predominant, 0.6 cm, margins negative
If you start by comparing the 8551/3 left lung tumor to the 8253/3 right lung tumor, M6 applies and these would be separate primaries (seq 01 and seq 02). How would we handle the third tumor, 8551/3, in the right lung? Seq 01: 3/21/18- left lung primary 8551/3 Seq 02: 11/3/18- right lung primary 8253/3 Is the right lung tumor 8551/3 a third primary, and if so, which M rule applies? I cannot find a rule that seems to fit completely. Rule M6 may apply if you were comparing the right 8551/3 tumor to the seq 02 8253/3 tumor. But how would you know to use the seq 02 histology code 8253/3 or seq 01 histology code 8551/3 for the comparison? I think M9 was designed for situations where you have multiple tumors involving both lungs but they didn’t biopsy all of them. Is that correct? If so, then we would be able to bypass M9. Would M11 apply since we already took care of two of the tumors with rule M6? If M11 doesn’t apply, it seems like you would get to M14.
Abstract two primaries applying Rules M6 and M9 s follows.
First, assign a histology for each tumor.
--LLL adenocarcinoma, acinar predominant 8551/3
--RUL invasive mucinous adenocarcinoma 8253/3
--RUL invasive adenocarcinoma, acinar predominant 8551/3
For the RUL, this is two primaries according to Rule M6, to subtypes in Column 3 of the histology table.
For the LLL and RUL, this represents the same primary as these are the same histology according to Rule M9.