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SINQs 20190083, 20180088, and 20130221 all indicate diagnoses of prostate adenocarcinoma, followed by a diagnosis of metastatic small cell carcinoma of the prostate are separate primaries because these are distinctly different histologies. Does this logic still apply for 2023 and later since Rule M4 was added to the Other Sites M Rules? Rule M4 states, “Abstract multiple primaries when the patient has a subsequent small cell carcinoma of the prostate more than 1 year following a diagnosis of acinar adenocarcinoma and/or subtype/variant of acinar adenocarcinoma of prostate.”

This patient has a 2018 diagnosis of prostate adenocarcinoma treated with radical prostatectomy, followed by a 2023 diagnosis of metastatic small cell carcinoma of the prostate diagnosed on a liver metastasis core biopsy. Rule M4 does not indicate whether it applies to subsequent biopsy confirmed metastatic tumor only. When a diagnosis of small cell carcinoma follows a diagnosis of prostatic adenocarcinoma, it is almost always confirmed in metastatic sites rather than in the primary site. Does the logic in the referenced SINQs above still apply for Rule M4?

The patient was not synchronously diagnosed with multiple tumors, but three separate tumors with three different histologies were diagnosed at different times and no more specific histology was provided for the NSCLC. The timing rules do not apply to this case (the tumors were not greater than 3 years apart and they were not synchronously/simultaneously diagnosed).

While NSCLC is a NOS histology for both adenocarcinoma and squamous cell carcinoma, it is unclear if Rule M8 should apply because NSCLC is not listed in Table 3 (Table 3 is not an exhaustive list). In some situations, Rule M8 would apply if the tumors were different histologies and one of the histologies was not listed in the Table. Does that logic still apply if one of the tumors is NSCLC? If NSCLC is excluded from Rule M8, is Rule M14 the appropriate M Rule for the 2022 NSCLC diagnosis?

Per Solid Tumor Manual Other Sites Rule M6, despite the number of areas of involvement, any presentation of Kaposi sarcoma is always a single primary. The primary site is skin using the Kaposi Sarcoma for All Sites Coding Guidelines (Appendix C, 2023 SEER Manual). 

Does SEER Program Coding and Staging Manual Laterality Coding Instruction #4 preclude the use of code 4 [Bilateral involvement at time of diagnosis...] if a patient presents with KS involvement of only both arms or only both sides of the face?

Patient was diagnosed with a pT1c prostate cancer in 2022. Patient was then treated with radical prostatectomy. No residual disease was found. Would the correct EOD prostate path extension code be 999 based on Note 8 (code 999 when radical prostatectomy is performed, but there is no information on the extension); or, would we use code 300 (confined to prostate) because the data item "...is used to assign pT category for prostate cancer based on radical prostatectomy specimens" and we know it was limited to the prostate because no residual was found?

Example: Patient is diagnosed with grade 1 well-differentiated neuroendocrine tumor of the ileum, confirmed on ileocolic resection in 2023. The final diagnosis is a 2.8 cm ileal mass, with focal lymph-vascular invasion and a single 0.6 cm tumor deposit within mesenteric fat; primary tumor completely resected with widely negative margins and 10 regional nodes negative for malignancy.

According to AJCC, mesenteric masses less than 2 cm should be stated in the pathology report as being present and collected by registrars but do not affect stage. EOD Regional Nodes has a code for large mesenteric masses greater than 2 cm only. How should we record these smaller tumor deposits if they are not supposed to affect stage?

An argument could be made to apply Rule M10 (timing rule which may result in reporting the case as an additional primary) because the 2022 primary included multiple non-invasive urothelial carcinoma tumors in both the bladder and other urinary sites (coded to site C689, not C679) following a long disease-free interval. While Rule M10 excludes multiple bladder tumors, does that also apply when new, multifocal urothelial tumors arise in both bladder and other urinary sites? Does the presence of any subsequent bladder tumor rule out the use of M10 and one must use M11 that indicates reporting this disease process is a single primary?

Example:  A prostate core biopsy showed intraductal carcinoma in 09/2022, which is an in situ tumor.  A core biopsy again showed intraductal carcinoma in 12/2022.  The subsequent radical prostatectomy in 04/2023, revealed multiple foci of invasive prostate adenocarcinoma with extensive intraductal carcinoma. 

Per Solid Tumor Rules, Other Sites, Rule M3, acinar adenocarcinoma of the prostate is always a single primary.  Note 4, this rule applies to subtype variants of acinar adenocarcinoma listed in Table 3, which has intraductal/ductal as a variant subtype of acinar adenocarcinoma. Does rule M3 apply to incidence cases (an invasive tumor following an in situ tumor)?