#1: Solid Tumor Rules (2018)
#2: Multiple primaries
#3: Brain and CNS
Source 1: 2018 Solid Tumor Rules
Notes: Malignant CNS, July 2019 Update
Solid Tumor Rules/Multiple primaries--Brain and CNS: What M rule applies to a clinically diagnosed right-sided parietal meningioma undergoing active surveillance, followed by a left-sided frontal anaplastic oligodendroglioma? See Discussion.
The patient has two, separate, non-contiguous tumors. One tumor is a benign meningioma and the other is a malignant oligodendroglioma.
The original plan was not to treat the asymptomatic meningioma. However, after worsening symptoms, imaging and resection proved a separate left frontal lobe malignant tumor.
Rule M5 is the only M Rule in the Malignant CNS Multiple Primary Rules, Multiple Tumors module that addresses separate non-malignant and malignant tumors. This rule provides only two criteria to follow when a malignant tumor follows a non-malignant tumor. The first criteria (for non-malignant tumor followed by malignant tumor) states:
--Patient had a resection of the non-malignant tumor (not the same tumor) OR
--It is unknown/not documented if the patient had a resection.
This patient did not have a resection of the original, separate, non-malignant tumor, but the treatment plan was known to not include a resection. Should Rule M5 also apply to cases where the patient never had treatment planned for the separate non-malignant tumor?
Apply 2018 Malignant CNS Solid Tumor Rule M5 and abstract multiple primaries when there are multiple CNS tumors, one of which is malignant /3 and the other is non-malignant /0 or /1. According to Note 3, a non-malignant CNS tumor and a malignant CNS tumor are always multiple primaries (timing and primary sites are irrelevant). Prepare two abstracts; one for the non-malignant and another for the malignant tumor.