minimal Common Oncology Data Elements (mCODE) Implementation Guide
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minimal Common Oncology Data Elements (mCODE) Implementation Guide, published by HL7 International Clinical Interoperability Council. This is not an authorized publication; it is the continuous build for version 2.1.0). This version is based on the current content of https://github.com/HL7/fhir-mCODE-ig/ and changes regularly. See the Directory of published versions

Disease Characterization

The mCODE Disease Characterization group includes data elements specific to the diagnosis and staging of cancer. This includes:

  • Cancer Diagnosis - the date and location (body site/position and laterality) of the cancer diagnosis.
  • Tumor Characteristics - histological classification, morphology, and behavior of the tumor cell, compared to that of a normal cell.
  • Cancer Stage Group - describes the severity of an individual’s cancer based on the magnitude of the original (primary) tumor as well as on the extent cancer has spread in the body. Understanding the stage of the cancer helps doctors to develop a prognosis and design a treatment plan for individual patients. Staging calculations leverage results from the previous two categories, along with prognostic factors relevant to the cancer type, in order to assess an overall cancer stage group (source: AJCC).

Representing the Cancer Diagnosis

The cancer diagnosis combines the type, site, and certain characteristics of the cancer. Depending on the EHR and provider organization, different code systems may be used, such as:

Because the use of these code systems vary in different institutions, mCODE supports all three. Two elements and one extension of the FHIR Condition Resource are involved with coding the cancer diagnosis: Condition.code, Condition.bodySite, and the HistologyMorphologyBehavior extension. How these attributes are used, depending on the code system, is captured in the table below:

Encoding Code Histology Morphology Behavior Extension Body Site
SNOMED Encoded Any descendant of 363346000 “Malignant neoplastic disease (disorder)” Any descendant of 367651003 “Malignant neoplasm of primary, secondary, or uncertain origin (morphologic abnormality)” Any descendant of 123037004 “Body structure”
ICD-10-CM Encoded Any ICD-10-CM primary code (precoodinated) n/a n/a
ICD-O-3 Encoded The code 363346000 “Malignant neoplastic disease (disorder)” Any ICD-O-3 Morphology Code (including /1, /2, or /3 suffix for primary cancers, and /6 suffix for secondary cancers) Any ICD-O-3 Topology Code

Implementers should reference the PrimaryCancerCondition and SecondaryCancerCondition profiles for further details on the use of these terminologies and associated value sets.

Representing Staging Information

Clinicians and pathologists assign stages to cancers according to rules defined in various cancer staging systems or methods. The staging system must always be specified alongside the stage, because it establishes the meaning of the stage code(s). One staging value can be included in the PrimaryCancerCondition, in the element Condition.stage.summary with the corresponding staging system in Condition.stage.type. However, a single value is often insufficient and does not allow for capture of provenance information related to staging, separate from the provenance of the cancer condition information.

For more detailed staging information, the user should provide a separate Observation resource conforming to the CancerStageGroup profile. A reference to this resource is provided in Condition.stage.assessment. The CancerStageGroup profile can be used with any staging system, but specifically, non-TNM staging systems, since a specialized TNM staging profile is provided. In CancerStageGroup, the following information must be provided:

  • Observation.category: fixed, required value of SNOMED CT 385356007 “Tumor stage finding (finding)”
  • Observation.focus: a reference to the primary cancer condition that was staged
  • Observation.code: a code that describes the specific type of stage being reported, for example, a TNM stage group or International Federation of Gynecology and Obstetrics (FIGO) ovarian tumor stage.
  • Observation.method: the staging system used to determine the value (from CancerStagingMethodVS), for example, SEER Extent of Disease or
  • Observation.valueCodeableConcept: the actual stage or category determined for the cancer.

For TNM staging, the TNMStageGroup profile should be used. This profile contains the stage group in Observation.valueCodeableConcept and provides optional references in Observation.hasMember to additional resources representing the T, N, and M categories. The Observation.code element value in TNMStageGroup is used to distinguish the type of staging, e.g., clinical or pathologic. For other types staging (e.g., retreatment (r) or autopsy (a)), a code indicating “other” staging type is used.

In mCODE, a single patient may have more than one staging panel, although this is not common in practice. If staging is repeated, the PrimaryCancerCondition reference to staging should be updated to the most recent staging information.

TNM Staging Information

TNM staging is used for many types of solid-tumor cancers. Clinical applications vary in their representation of T, N, and M staging category values, falling into one of two naming conventions:

  • Prefixed with a staging classification abbreviation (e.g.: cT3, ypT3). This is the coding convention returned by American Joint Commission on Cancer (AJCC) in their digital data content retrieved via the AJCC Application Programming Interface (API).
  • Without a prefixed staging classification abbreviation (e.g.: T3).

mCODE strongly recommends that the implementers align with AJCC’s convention of representing the staging category value including the classification prefix. This code convention is aligned with the AJCC’s digital data and clearly distinguishes the staging classification as clinical (c), pathologic (p), neoadjuvant (yc or yp), restage (r), or autopsy (a) without having to retrieve further context from the model. The selected prefix MUST be consistent with the Observation.code value.

Several widely-used terminologies in the cancer domain, including ICD-O-3 and AJCC staging, are proprietary and cannot be reproduced in this guide. SNOMED-CT has reached an agreement with AJCC to create SNOMED codes that correspond to AJCC stages. mCODE uses these SNOMED codes where applicable, but licensed sites may continue to use AJCC codes and still be in conformance with mCODE. Under the Fair Use doctrine, examples illustrating mCODE’s representation of cancer diagnoses may use the more familiar AJCC staging values for the purposes of implementation guidance to FHIR developers.

Non-TNM Staging Information

Not all cancer types are staged with a TNM-based staging system, including hematological cancers like leukemias, multiple myeloma, and some lymphomas. Some specialized solid tumors like gynecologic tumors are staged using the FIGO (International Federation of Gynecology and Obstetrics) staging system. Other non-TNM staging systems include Rai, Binet, and Cottswold. The staging system should be represented with a code from the CancerStagingMethodVS value set, if available.

Non-TNM staging results are represented using the profile CancerStageGroup. Prognostic factors related to the cancer stage group can be specified with the Observation.derivedFrom element. For example, a hemoglobin lab result which was evaluated in the staging of chronic lymphocytic leukemia using the Binet staging system can be referenced under Observation.derivedFrom element. This example of Binet staging illustrates how this could be represented.

Body Locations

Body locations in FHIR are typically represented using a single code. However, a single code is often insufficient to describe where a tumor is located, where a surgery is targeted, or where a radiation treatment is focused. When a single code is insufficient, FHIR recommends using a BodyStructure. This is appropriate when the BodyStructure is something to be tracked over time, for example, in the case of Tumor. But generally, it is better to describe a body location without using an additional resource.

mCODE has adopted an approach that allows the user to add additional code or codes to further define the body site, without the need to create an independent resource. This takes the form of the LateralityQualifier and BodyLocationQualifier extensions. These extensions can be used to specify laterality, directionality, and plane.

Tumor Marker Tests

Tumor markers are key prognostic factors in calculating cancer staging, identifying treatment options, and monitoring progression of disease. For example, an abnormal increase in prostate-specific antigen (PSA) levels is a prognostic factor for prostate cancer. Other tumor markers include estrogen receptor (ER) status, progesterone receptor (PR) status, carcinoembryonic antigen (CEA) levels, among others. mCODE distinguishes tumor marker tests from sequencing-based genomic tests measured at the DNA, RNA, or chromosomal level. The latter are addressed in the Genomics section.

mCODE includes single FHIR profile, TumorMarkerTest, for all labs involving serum and tissue-based tumor markers. This is less than ideal, since without specifying units of measure or answer sets on a per-test basis, reporting could vary. However, given the large number of tumor marker tests, creating individual profiles was judged impractical.

Profiles

Extensions

Value Sets

Code Systems