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Assign primary site as colon, NOS (C18.9) when the only information about the diagnosis you have is "colorectal cancer."

We consulted with a subject matter expert who believes that colon, NOS is closest to being correct and that rectosigmoid is not appropriate.

If further information becomes available through further workup and/or treatment, update the primary site as appropriate.

We will add clarification to the 2027 SEER Manual, Appendix C, Colon Coding Guidelines.

Do not code Thyrogen as hormone therapy when given as a stimulating agent in I-131 therapy. The therapeutic agent is I-131.

The Thyrogen/thyroid stimulating hormone (TSH) is sensitizing the gland to absorb more I-131. Thyrogen/TSH is a trophic hormone so it can cause growth of cancer cells. Thyroid hormones are given in follicular and papillary thyroid cancers to suppress TSH. Although Thyrogen can promote cancer growth its use in Thyrogen stimulated I-131 radioactive therapy is justified (benefits exceed the risk), since the use is short (2 days) and the high amount of I-131 would kill cancer cells in addition to majority of thyroid tissue.

We will update the Thyrogen entry in SEER*Rx and clarify in the next release of the SEER manual, Appendix C Coding Guidelines for Thyroid.

Do not report a case of atypical lobular hyperplasia of the breast until/unless it is definitively diagnosed as LCIS or another reportable neoplasm. WHO defines this as a non-invasive lobular neoplasia. Atypical lobular hyperplasia does not have an ICD-O code and is not equivalent to in situ.

The 2027 version of the Hematopoietic Manual (release October 2026) will include the following in the Case Reportability Instructions, pg. 40:

4. “Consistent with” for reportability and casefinding is now a definitive diagnosis and is no longer ambiguous terminology. This is for hematopoietic neoplasms ONLY.

a. “Consistent with” has become a very common way for pathologists to document diagnoses for Hematopoietic neoplasms. In order to ensure that hematopoietic cases are being reported, “consistent with” has now become definitive terminology for casefinding and reportability (see Histology Coding Instructions for assigning histology).

b. Do not apply this instruction to casefinding and reportability for Solid Tumors.

5. Report the case when the diagnosis of a hematopoietic neoplasm is preceded by one or more of the ambiguous terms listed below:

a. This instruction pertains to reportability and case finding only. See the Histology Coding Instructions, #3-5 for instructions on assigning histology with ambiguous terminology (note that “consistent with” has been removed. See Note #4) .

• Apparently
• Appears
• Comparable with
• Compatible with
• Favor(s)
• Malignant appearing

Updated June 2026

Code the first course of treatment as active surveillance. Chemotherapy is second course of treatment based on this scenario due to progression.

We will be adding clarification about this type of scenario to the treatment rules in the 2027 updates, which will be released October 2026.

Accession two primaries when a patient has synchronous, separate ductal and lobular tumors using Rule M13, Breast STRs, 2026 Update. Ductal carcinoma (8500/3) and lobular carcinoma (8520/3) are distinct histology terms and codes that are in different rows in Table 3. This is a modification of Rules M10 and H28 from prior versions of the STR Manual.

Assign histology as 8340/3 for IEFVPTC using the STR Manual, 2026 Update. Rule M18, Note 2, of the Other Sites STR state: Invasive encapsulated follicular variant of papillary thyroid carcinoma and Infiltrative follicular variant of papillary thyroid carcinoma share a histology code (8340) but are distinctly different entities. They are on separate rows of the table.

WHO Classification of Endocrine and Neuroendocrine Tumors, 5th ed., indicates that after classic PTC, the follicular variant of PTC (FVPTC) is the second most common histological subtype of PTC. Two major forms are known, infiltrative FVPTC and invasive encapsulated FVPTC. The majority of follicular PTCs are encapsulated FVPTCs, whereas infiltrative FVPTC is quite rare and clinically behaves like classic PTC.

Assign code A280 for current unilateral oophorectomy with hysterectomy or with a previous history of hysterectomy.

We will remove the text ‘(salpingo-)’ from the Ovary surgery code A280 SEER Note in the next release of SEER Manual.

Report severe dysplasia for selected sites. Not all high grade dysplasia and severe dysplasia are reportable. Refer to the list of examples in the SEER Manual Reportability Section and Appendix E, Reportable and Non-reportable Examples. Check also for other standard setters, state, and local reportability requirements.

High grade dysplasia, severe dysplasia, and carcinoma in situ are equivalent terms with behavior /2. Refer to ICD-O, WHO Classification of Tumors, and the SEER Solid Tumor Rules for preferred histology terms and codes. For example, WHO Classification of Head and Neck Tumors, 5th edition, states carcinoma in situ in the oral cavity is synonymous with severe dysplasia though it is not a recommended term.

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.