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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?

The patient underwent a resection of the transitional meningioma in 2012, but residual tumor was left behind. The patient was on surveillance until imaging showed growth of the residual tumor. The resection in 2022 proved atypical meningioma.

Rule M2, the first rule that applies, indicates this situation represents a single primary (a single tumor). However, Rule M4 states the transformation from a benign meningioma to a borderline meningioma would only be a single primary if the meningioma was a NOS.

This patient has microscopic confirmation of a meningioma showing different subtypes/variants (listed in Column 3, Table 6). Should this be accessioned as multiple primaries based on the transformation and distinctly different histologies?

Historically, synchronous ductal and lobular tumors have been accessioned as a single primary. These were previously covered under Rule M10, which was removed from the (STR) Manual 2026 Update. While the previous iteration of Rule M10 was problematic, the main issue related to the lack of a timing component within the rule (i.e., indicating it applied to synchronous ductal and lobular tumors).

Using the current Breast STR, when there are two (or more) simultaneous tumors which are not mixed lobular and ductal within each tumor, the applicable M Rule is Rule M13: Abstract multiple primaries when separate/non-contiguous tumors are on different rows in Table 3. To apply the M Rules, a provisional histology must be assigned to EACH tumor so we cannot code each tumor as 8522 before we start applying the M Rules. These provisional histologies would be 8500 and 8520, and these are on different rows in Table 3.

Core biopsy of left breast at 2:00: Invasive ductal carcinoma, Nottingham score 6/9.

Core biopsy of left breast at 4:00: Invasive mucinous carcinoma (variant of ductal carcinoma), Nottingham score 5/9.

Post neo-adjuvant mastectomy: Main (largest tumor): Invasive ductal carcinoma, upper outer quadrant grade 2. Secondary tumor: mucinous carcinoma, grade 1 at 4:00.

The right breast ultrasound shows a 1.4 cm mass at 8 o'clock and a separate mass .6 cm at 7 o'clock (site code for both C50.5). Pathology report: Right 8 o'clock core needle biopsy fragments of intracystic noninvasive papillary carcinoma (8504/2), right 7 o'clock core needle biopsy fragments of intracystic noninvasive papillary carcinoma (8504/2). Then, another facility performs a right breast lumpectomy (operative note not available). Outside Facility: Right breast lumpectomy pathology shows invasive ductal carcinoma .6cm (8500/3) multifocal DCIS .5cm greatest dimension tumor site right breast NOS.

Should we use Rule M12-Abstract multiple primaries when separate/non-contiguous tumors are on different rows in Table 3 in the Equivalent Terms and Definitions. Timing is irrelevant. Note: Each row in the table is a distinctly different histology. So would this be two primaries C50.5 (8504/2) and C50.9 (8500/3)?

The patient was initially diagnosed with invasive mammary carcinoma of the right breast in 2018, treated with lumpectomy, sentinel node biopsy, radiation, and hormones. Hormones were discontinued early due to dysfunctional uterine bleeding.

The WHO Blue Books do not include dedifferentiated carcinoma as a valid histology for the breast.  However, there is known to be progression of ductal carcinoma that is essentially dedifferentiation of an estrogen receptor, progesterone receptor, and HER2 breast carcinoma to a triple negative "dedifferentiated" carcinoma which it appears this patient has. Whether we should accession this as a separate 8020/3 primary per M14 is unclear and the Solid Tumor Manual does not address this scenario.

Historically, multiple invasive ductal and lobular carcinomas diagnosed within 5 years were abstracted as a single primary. However, it is not clear if Rule M10 or M14 applies to this situation per the 2023 Solid Tumor Rules updates.

Rule M10 addresses multiple tumors of carcinoma of no special type (NST)/duct and lobular, but there is no timing criteria mentioned. Does M10 apply to cases diagnosed synchronously, or metachronously, or at least within 5 years? Should Rule M10 include a Note instructing registrars to accession a single primary for the scenario in question?

If timing matters for Rule M10, then the next rule that applies is M14. Rule M14 instructs one to abstract multiple primaries when separate/non-contiguous tumors are on different rows in Table 3, and carcinoma NST/duct and lobular carcinoma are on separate rows in Table 3.

In the examples below, are these a single or multiple primaries?

Example 1:

Tumor 1:  C509/left breast, 8520/2 (in situ lobular carcinoma), dx date-01/10/2019

Tumor 2:  C509/ left breast, 8500/3 (carcinoma NST), dx date-08/19/2021

Example 2:

Tumor 1:  C509, right breast, 8520/2, dx date 06/26/2014

Tumor 2:  C508, right breast, 8500/3, dx date-05/23/2019

There seems to be some conflicting info on this. In the 2020 Breast Rules there was a note add to the revision history. “M10 Same behavior requirement re-added.” Which is not in the rules now, nor was it noted to the revision changes in the last two change logs.

Inquiry 20200070 would seem to indicate that this is multiple primaries, but that contrasts with 20230010 which would seem to indicate a single primary, and an ASK A SEER Registrar question that we received a response to. I don’t see a scenario where rule M17, an invasive tumor DX more than 60 days after an in situ tumor would come into play.

If behavior no longer applies to rule M10, at what point did that change get made? Please advise.

The 11/2023 lower gum tumor is a separate tumor occurring after a disease-free interval, so we know the Head and Neck Multiple Tumors Module applies. However, our staff is having difficulty applying the rules to this particular scenario with consistent results.

Is the 11/2023 SCC a non-reportable recurrence per M12, since M4 is ignored due to patient’s prior 2017 C031 (lower gum) primary, and then M6 is ignored due to patient’s prior 05/2022 C023 primary?

Or is the 11/2023 SCC a new primary per M4, since the last diagnosis was in a site differing at the third character (C03 vs C02)? If M4 does not apply due to patient's previous C03 primary, then does M6 apply since it has been more than 5 years since the previous C03 primary?