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Cancer Code Constructor
Build ICD-10-CM oncology codes axis by axis — primary site, histology, status, metastatic sites, and complication co-codes with official sequencing guidance.
FY2027 update in progress. The FY2027 ICD-10-CM code set (effective 10/01/2026) is still loading, so a code may be missing or a deleted code may still show. Confirm against official CMS files before billing.
The 8-Axis Cancer Coding Decision Framework
Why is the patient being seen? This drives sequencing — the principal/first-listed code.
Is the coded cancer the originating primary site or a metastatic secondary site?
When both primary and secondary are documented, sequence the one being treated first.
Histology type drives the correct chapter range.
- C00–C75 Carcinoma / solid tumors (site-specific)
- C7A Neuroendocrine / carcinoid tumors
- C7B Secondary neuroendocrine tumors
- C76 Ill-defined or secondary sites
- C81–C86 Hodgkin & Non-Hodgkin Lymphoma
- C88–C90 Myeloma, macroglobulinemia
- C91–C95 Leukemia (ALL, CLL, AML, CML…)
- C96 Other lymphoid / hematopoietic
- D00–D09 In situ neoplasms
- D37–D48 Uncertain behavior neoplasms
Where did the malignancy originate? Drives the 3rd–5th character of the C-code.
Active vs. historical changes the entire code block used.
⚠ Guideline I.C.2.d: Do not use Z85 if the malignancy is still being actively treated. Query the provider if documentation is ambiguous.
Code each documented metastatic site with a C77–C79 code. Code all documented sites.
- C77.0–C77.9 Secondary — lymph nodes (by region)
- C78.0–C78.7 Secondary — respiratory & digestive organs
- C78.00 Secondary — lung, unspecified
- C78.7 Secondary — liver
- C79.0 Secondary — kidney & renal pelvis
- C79.31 Secondary — brain
- C79.51 Secondary — bone
- C79.82 Secondary — genital organs
When multiple sites are documented, code all of them. Use M84.5xx for pathologic fracture in neoplastic disease when bone mets cause fracture.
When the encounter is for administration of therapy — these are first-listed.
- Z51.11 Encounter for antineoplastic chemotherapy
- Z51.12 Encounter for antineoplastic immunotherapy
- Z51.0 Encounter for antineoplastic radiation therapy
⚠ Guideline I.C.2.e.1: Z51.11 / Z51.0 are always first-listed when the encounter is specifically for that treatment. The cancer code follows as an additional diagnosis.
These are always additional codes — never sequenced first — unless the complication is the reason for the encounter.
Anemia
GI / Nutritional
Long-term therapy
Pain
Build My Code
Answer each question — your code set and sequencing guidance will generate below.
Your Cancer Code Set
| Sequence | Role | Code | Description | Guideline |
|---|
Sequencing Guidance
Look up codes in Lynceus
Key Coding Guidelines — Neoplasms (Chapter 2)
I.C.2.a — Treatment directed at malignancy
The malignancy is sequenced as the principal diagnosis when the encounter is for treatment directed at the cancer itself.
I.C.2.b — Treatment of secondary site
When treatment is directed at the secondary site, the secondary malignancy is the principal diagnosis even if the primary is still present.
I.C.2.c — Coding & sequencing of complications
Coding and sequencing of complications associated with the malignancy or with the therapy thereof are subject to the following guidelines.
I.C.2.d — Primary malignancy previously excised
When a primary malignancy has been previously excised and there is no further treatment and no evidence of existing primary, code the condition as personal history using Z85.
I.C.2.e — Admissions/encounters involving chemo, immunotherapy, and radiation
Z51.11, Z51.12, and Z51.0 are sequenced first when the encounter is specifically for one of these therapies. The malignancy is an additional diagnosis.
I.C.2.f — Admission/encounter for pain due to malignancy
Code G89.3 for pain documented as being related to a malignancy. Sequence based on the focus of the encounter — G89.3 first for pain control; cancer code first for treatment of the malignancy.
Cancer code construction requires clinical documentation review and professional judgment. Codes generated here are decision-support references — not certified coding determinations. Always verify against the current ICD-10-CM Official Guidelines for Coding and Reporting.