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Oncology Data Specialists (ODS) are, as stated by the National Cancer Registrars Association (NCRA): “… data information specialists that capture a complete history, diagnosis, treatment, and health status for every cancer patient in the U.S. The curated data provides essential information to researchers, healthcare providers, and public health officials to better monitor and advance cancer treatments, conduct research, and improve cancer prevention and screening programs.

In recognition of March’s Colon, Kidney, and Multiple Myeloma Awareness Month, along with our continued effort to help shine a light on the benefits of cancer registries, we will examine single-primary solid tumors, multiple-primary solid tumors and recurrences using the Colon (including rectosigmoid junction and rectum), Kidney and Multiple Myeloma as examples.

For the scope of this article, we will consider the colon and kidney solid-tumor only sites and multiple myeloma not a solid tumor disease. In the cancer registry we utilize the SEER (Surveillance, Epidemiology and End Results) Solid Tumor Rules Manual (formerly The SEER Multiple Primary/Histology Manual prior to 1/1/2018, available online) to determine whether a solid-tumor cancer diagnosis represents a single primary, multiple primary and whether the case is a recurrence.

Perhaps the simplest rule (for solid tumors), is that a single tumor is always a single-primary cancer case.

The situation can get more complicated when there are multiple tumors because multiple tumors do not always equate to multiple primary cancer diagnoses. Determining multiple primary cancer cases in the colon is determined by referencing 13 rules and in the kidney 11 rules.

For the colon, in general, a diagnosis may represent multiple primaries, if the second tumor is not in the colon, is a different histology, or is in a different colon subsite (there are 8 subsites). The colon has a “timing” rule such that If a second tumor arises one year or more after the patient is determined to have no evidence of disease from the original cancer or is diagnosed with invasive cancer greater than 60 days after a non-invasive cancer, you may have a multiple primary situation.

When a second tumor is diagnosed in a site other than the kidney (which would include a second tumor found in the contralateral kidney), the diagnosis may represent a multiple primary case. The “no evidence of disease” timing rule for the kidney is three years. If there are tumors with different histologies, or if an invasive cancer is diagnosed more than 60 days after a non-invasive cancer, this then can be considered a multiple primary.

The term “recurrence” can have two quite different meanings when found in the medical record. A solid tumor recurrence, or “recurrent cancer” can be a statement indicating a patient currently has cancer at a point in time after they were diagnosed with cancer. For oncology data specialists (ODS) and the cancer registry, a recurrence represents not only that a patient currently has cancer, but the current cancer is from a prior cancer diagnosis (single primary). In other words, when a patient is documented to have cancer again, the ODS has gone through the solid tumor rules manual and determined that the current cancer is not a multiple primary case but rather is the original cancer that may have been found in the same site or metastasized (multiple primary rules are automatically not applied to tumors identified as metastases) to a different site(s).

We have discussed the Colon and Kidney (solid tumors) and the use of the solid tumor rules manual which are not applicable in cases such as Multiple Myeloma. Multiple Myeloma, a hematopoietic malignancy, has a different coding manual, The SEER Hematopoietic and Lymphoid Neoplasm Database (available online) in conjunction with the SEER Hematopoietic Coding Manual, and a vastly different set of rules.

These references help to determine staging, provide other diagnostic information, and help to determine if a patient has multiple myeloma by the presence of multiple plasmacytomas (without a timing rule as in the case of Colon and Kidney solid tumor rules). There aren’t any single versus multiple primary rules for multiple myeloma, which is a major difference from the Colon and Kidney, as Multiple Myeloma is always a single primary, and a patient can only have oner per lifetime.

When an ODS determines a case to be a single primary (or in a diagnosis of multiple myeloma) a single abstract is completed. If a case is a multiple primary, an abstract is completed for each of the primary cancers, which are considered independent of one another for follow-up and determining recurrences. The first recurrence (if one does occur), as determined by the Solid Tumor Rules or the Hematopoietic and Lymphoid Neoplasm Database, is documented in the abstract and coded by date of recurrence and type of recurrence (local, regional, distant, systemic, etc.), and the cancer status is updated from “no evidence of disease” to “active disease”.



SEER SOLID TUMOR RULES: 2023 and 2024 Solid Tumor Rules (

SEER HEMATOPOIETIC AND LYMPHOID DATABASE: SEER Hematopoietic and Lymphoid Neoplasm Database (

SEER HEMATOPOIETIC CODING GUIDE: Hematopoietic and Lymphoid Neoplasm Coding Manual Published August 2021 (