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Code as undifferentiated round cell sarcoma (8803/3).

The CIC rearrangement exists as a distinct molecular and clinical subset of small round cell tumors, and though similar, is felt to be a distinct entity from Ewing sarcoma. According to WHO Classification of Soft Tissues and Bone, 4th Edition, CID-DUX4 is a recurrent gene fusion associated with pediatric round cell undifferentiated soft tissue sarcoma (USTS). Although the genes involved in the fusion are different from those in Ewing sarcoma, the CIC-DUX4 protein has been shown to upregulate genes of the ETS family of genes thus providing a molecular link between Ewing sarcoma and round cell USTS. In contrast, there are strong arguments to suggest that Ewing-like sarcomas represent a separate and distinct entity.

Code histology for this endometrial primary to serous carcinoma 8441/3. Capture "high grade" in the grade field as instructed in the grade coding manual.

"High grade serous carcinoma" has specific clinical and histopathologic features found in ovarian tumors.

Assign histology as 9505/3.  WHO Classification of Central Nervous System (CNS) Tumors describe ganglioglioma as a well-diffferentiated and slow-growing glioneuronal neoplasm.  While WHO does not recognize the histology/behavior combination 9505/3, the 2021 CNS Solid Tumor Rules identify non-malignant tumors that have the potential of transforming to a malignant tumor (new primary).  Ganglioglioma (9505/1) is listed with the transformed histology and instructs us to code as anaplastic ganglioglioma (9505/3).

For tumors diagnosed prior to 2007:

Assign code 8560 [adenosquamous carcinoma]. According to our pathologist consultant, the mix of adenocarcinoma and squamous carcinoma is adenosquamous carcinoma. Adenosquamous tumors are rare, but known, representing 3-4% of pancreatic carcinomas.

For tumors diagnosed 2007 or later, refer to the MP/H rules. If there are still questions about how this type of tumor should be coded, submit a new question to SINQ and include the difficulties you are encountering in applying the MP/H rules.

For this example: 1. Code HT as treatment on the date of diagnosis for the second primary. 2. Code Systemic/Surgery Sequence as 4. 3. Do not code neoadjuvant data items as neoadjuvant started/completed. The HT given would not qualify for neoadjuvant therapy since the intent of the HT was not neoadjuvant. The HT would affect the second primary, but it is still not neoadjuvant. 4. Code clinical and pathological tumor size accordingly, based on the imaging and the pathological findings. 5. Code Extent of Disease data items based on the pathological findings since pathological findings take priority over clinical and this is not neoadjuvant therapy.

Armour thyroid is listed under "Thyroid" in SEER*Rx and in Appendix C Thyroid Coding Guidelines of the 2026 SEER Program Coding and Staging Manual. Code natural thyroid products as hormonal therapy in papillary, follicular, or oncocytic thyroid carcinoma. Thyroid histology must be known as coding depends on histology. Do not code if it is medullary or anaplastic thyroid carcinoma. If histology is unknown, assign Hormone Therapy as code 99.

In papillary, follicular, and oncocytic carcinoma, natural or synthetic thyroid hormone products have a dual role:

1. Suppression of thyroid stimulating hormone (TSH): This is cancer directed therapy since the tumor cells of the above mentioned morphologies express TSH receptor. TSH is a trophic hormone that can promote tumor growth.

2. Hormonal replacement therapy to treat post-surgical or post-radiation hypothyroidism. C-cells in medullary carcinoma do not express TSH receptor, thus, TSH suppression would not be indicated. However, replacement hormonal therapy with synthetic or natural thyroid hormones post surgery is given to treat the post-surgical hypothyroidism. In operable thyroid anaplastic carcinoma, the goal of levothyroxine therapy is hormone replacement.

The Thyroid Coding Guidelines are being updated to include oncocytic thyroid cancer in the 2027 release of the SEER Manual.

Code Sandostatin (octreotide acetate) as hormonal therapy when given including:

· SSTR 2 positive meningioma (NCCN, 2025: smaller studies support the use of targeted therapy including somatostatin)

· Neuroendocrine tumor (NET) (NCCN, 2025: Tumor control: antitumor effect is supported by studies for well-differentiated G1/G2 gastro-entero-pancreatic NET. In lung/thymic NET, somatostatin analogues may be considered if metastatic or SSTR positive).

The SEER*Rx entry for Octreotide Acetate was updated as studies showed somatostatin analogs may shrink tumors or inhibit further growth.

Code dexamethasone in KRd regimen (and any other regimen for multiple myeloma containing dexamethasone) as hormonal therapy. Please note that majority of the regimens for multiple myeloma are not in SEER*Rx currently.

The SEER*Rx entry for KRd regimen was updated to indicate that dexamethasone should be coded. The change was done to correct the contradiction with the SEER manual which states, "Code the hormonal agent given as part of combination chemotherapy (e.g., R-CHOP), whether it affects the cancer cells or not" and the SEER*Rx entry for dexamethasone which directs to code it for multiple myeloma.

Updated December 2025

Do not code levothyroxine given to treat hypothyroidism or as cancer treatment for medullary carcinoma when given as replacement therapy and not as thyroid stimulating hormone (TSH) suppression therapy. Thyroid hormone therapy is generally coded as treatment for follicular, papillary, and oncocytic thyroid carcinomas.