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The Solid Tumor Rules indicate bladder tumors that are urothelial carcinoma (8120) and small cell carcinoma (8041) are separate primaries per Rule M13 (Abstract multiple primaries when separate/non-contiguous tumors are on different rows in Table 2). These are distinctly different histologies and, presumably, one would want to capture the small cell carcinoma (or small cell carcinoma component) as this has a worse prognosis.

However, if a subsequent bladder tumor is composed of invasive urothelial carcinoma and small cell neuroendocrine carcinoma, the histology is coded as 8045/3 per Rule H4, but this is not abstracted as a multiple primary. The only M Rule that applies is Rule M18 (Abstract a single primary when tumors do not meet any of the above criteria). The mixed histology code 8045 is not included in Table 2, so none of the histology-based M Rules apply. Is the subsequent mixed invasive urothelial and small cell carcinoma tumor (8045/3) the same primary as a previously diagnosed invasive urothelial carcinoma (8120/3) when these tumors are diagnosed within three years?

Glioblastoma multiforme is listed as a synonym for the preferred term glioblastoma, NOS (9440) per Table 3 Column 2. Therefore, it seems reasonable to assume that a diagnosis of glioblastoma, NOS would be a new primary if it followed a glial or astrocytic tumor. However, in general, the Solid Tumor Rules use the preferred terminology and/or indicate when a specific rule also includes any tumor diagnosed as a subtype/variant. Rule M6 does not explicitly include a diagnosis of glioblastoma, NOS or any of its subtypes/variants (e.g., glioblastoma IDH-mutant or gliosarcoma). Does Rule M6 apply to any diagnosis of glioblastoma, NOS and any of its synonyms or subtypes/variants?

The patient has one tumor each in the left parietal and left medial temporal lobe. The tumors were excised. The final diagnosis for the left parietal tumor is glioblastoma, IDH-wild type. he final diagnosis of the left medial temporal tumor is, at least anaplastic astrocytoma, WHO grade III; see comment. The comment states: There is a single focus of vascular hyperplasia, separate from neoplastic cells. No necrosis is identified. These findings on their own would warrant a diagnosis of anaplastic astrocytoma, WHO grade III. However, in the context of the patient's glioblastoma in the left parietal lobe, and imaging showing ring-enhancing lesions of the parietal and temporal lobes, this specimen is favored to be an un-sampled glioblastoma, WHO grade IV. The Solid Tumor Rules indicate we may no longer use terms like favor(s) to code the histology, leaving the final diagnosis as the priority source for coding histology per the Histology coding rules.

The tumor board review confirmed that, despite the anaplastic astrocytoma on pathology, they felt strongly that this is a multifocal glioblastoma and not an anaplastic astrocytoma. Both the pathologist's comment and the tumor board's assessment indicate this patient does not have two primaries. However, the Solid Tumor Rules do not give priority to the tumor board's assessment over the pathology, and registrars are not to use ambiguous terms to code histology thus leaving the two histologies to consider. Per the Solid Tumor Rules, one tumor that is glioblastoma and one tumor that is anaplastic astrocytoma are multiple primaries per M11 (Abstract multiple primaries when separate, non-contiguous tumors are on different rows in Table 3 in the Equivalent Terms and Definitions. Timing is irrelevant).

As a central registry, we cannot ask the pathologist or attending physician for clarification as suggested in Section 3 of the Malignant CNS and Peripheral Nerves Equivalent Terms and Definitions. We can only follow the current Solid Tumor Rules. In doing so, we would have to ignore both the pathologist's and tumor board's assessment that this patient has multifocal glioblastoma. Is there any concern that this will lead to over-reporting?

Is an M rule needed to address multiple tumors and Note 2 in Table 3? Does Note 2 in Table 3 apply when multiple tumors exist and one tumor contains only ductal carcinoma?

The M Rules currently confirm that a metaplastic carcinoma (whether it is involved with ductal or lobular) and a separate ductal carcinoma are separate primaries because these histologies are on different rows in Table 3 (separate primaries per M14). There is no specific rule regarding metaplastic carcinomas in the Multiple Tumors (M Rules) module, so presumably, the presence of a separate ductal carcinoma is not lumped into Note 2 in Table 3 for metaplastic carcinoma.

However, the note is confusing when there are multiple tumors involved because it appears to the registrars there are two options for coding the histology. To some registrars, the rules indicate it does not matter if the tumor is predominantly ductal carcinoma as long as some percentage of metaplastic carcinoma is present, code histology to metaplastic carcinoma. For other registrars, the presence of solely a ductal carcinoma in a second tumor is a separate primary from the separate metaplastic carcinoma.

The M rules and Note 2 need to clarify this issue to promote consistency.

This question was prompted from preparing SEER*Educate coding exercises. We will use the answer as a reference in the rationales.

Patient has a 1.7 cm encapsulated papillary carcinoma staged as pTis located 2 cm from the nipple and Paget disease of the nipple on mastectomy pathology.

There is no indication in Table 3: Specific Histologies, NOS/NST, and Subtypes/Variants that encapsulated papillary carcinoma is a subtype of ductal carcinoma. Rule M8 notes that if the histology of the underlying tumor is any histology OTHER THAN duct or subtypes of duct, one should continue through the rules. But if M9 applies to this case, then incidence reporting will be increased in comparison to prior years.

In the April and July 2019 updates to the Solid Tumor Rules, the term simultaneous and Note 1 indicating histologies must be the same behavior were removed from rule M10 (ductal and lobular are a single primary).

We would like to confirm that rule M10 is the correct rule to apply to this case. This case is an invasive diagnosis approximately 4.5 years after an in situ diagnosis, so it seems like M17 should apply (invasive tumor following an in situ tumor more than 60 days later are multiple primaries).

An invasive tumor following an in situ tumor more than 60 days later of the same histology is a new primary. Similarly, it seems like an invasive tumor following an in situ tumor more than 60 days later of different histologies should be a new primary.

The patient was never treated for the 2016 diagnosis, so the 2019 diagnosis is the same tumor that has progressed. Prior SINQ 20091096 for a similar case type cited multiple primaries per the 2007 Multiple Primaries/Histology Rules, Rule M8, the same rule as the current Solid Tumor rule M17, because this is to be reported as an incidence case.

However, it seems like Solid Tumor Rule M3 would apply because a single tumor is a single primary, and behavior of the 2016 primary would then be updated from /2 to /3. It is unclear how one would advance to the Multiple Tumors module and apply M17 because there is really only a single tumor in this case.

If the term discontinuous foci means separate tumors, then rule M14 would apply making these multiple reportable tumors.

Example: Right breast core biopsy found ductal carcinoma in situ in the upper outer quadrant. Subsequent resection has a final diagnosis of invasive mucinous carcinoma, grade 1, measuring approximately 7 mm, with close margins. See staging summary. Gross description mentions only the primary tumor with associated marker clip from previous biopsy.

Breast Cancer Staging Summary lists (testing and margins removed for brevity):

Procedure type: Lumpectomy.

Specimen laterality: Right.

Tumor size: 7mm.

Histologic type: Invasive mucinous carcinoma.

Histologic grade (Nottingham histologic score): Grade 1, (score 5/9).

Tumor focality: Single focus.

Lymph-vascular invasion: Not identified.

Treatment effect: No known therapy.

Ductal carcinoma in situ (DCIS): Present.

Architectural pattern: Cribriform.

Nuclear grade: Grade 1.

Necrosis: Not identified.

Calcifications: Not identified.

Estimated size/extent of DCIS: Spanning an area measuring 15mm.

Pathologic stage: pT1b, pNx. (AJCC 8th ed).

Distant metastasis: Not applicable.

Additional findings: Background lobular carcinoma in situ (LCIS), flat epithelial atypia (FEA), and atypical ductal hyperplasia (ADH).

Recognizing the addition of the behavior requirement into this rule is an attempt to stop non-synchronous ductal carcinoma and lobular carcinomas from being accessioned as a single primary (SINQ 20200022), the issue with using behavior rather than timing is that now, synchronous separate/non-contiguous tumors that are invasive carcinoma NST (8500/3) and lobular carcinoma in situ (8520/2) (or vice versa) are separate primaries per M14.

Lobular and carcinoma, NST are separate rows in Table 3, so we cannot stop at M10 and code the mixed histology because there are two separate histologies with different behaviors. There is no rule that states we can just ignore the in situ tumors for the purpose of applying the M Rules. (We are instructed to ignore the in situ when coding histology only in certain circumstances.) The problem with Rule M10 appears to be related to timing.

This question was prompted from preparing SEER*Educate coding exercises. We will use the answer as a reference in the rationales.