C78.80 ICD-10-CM Code: Secondary malignant neoplasm of unspecified digestive organ
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of ill-defined, other secondary and unspecified sites (C76-C80)
C78.80
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceSecondary malignant neoplasm of unspecified digestive organ
Cancer that has spread to an unspecified digestive organ from a primary cancer elsewhere, when the exact organ cannot be determined.
Buddy Insight
Secondary malignant neoplasm of an unspecified digestive organ indicates metastatic cancer to the gastrointestinal system without precise localization.
CMS-HCC V28
MappedHCC 17
RAF 4.209
CMS-HCC V24
MappedHCC 8
RAF 2.659
ACA/HHS
MappedHCC 8
Varies by metal level
ESRD/PACE
MappedHCC 8
RAF 0.353
RXHCC
MappedHCC 18
RAF 1.949
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for C78.80 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for C78.80 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for C78.80 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for C78.80 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for C78.80 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for C78.80 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for C78.80 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is C78.80 an HCC code?
Yes. C78.80 (Secondary malignant neoplasm of unspecified digestive organ) maps to Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic under the CMS-HCC V28 risk adjustment model (and Metastatic Cancer and Acute Leukemia under V24), with a community non-dual aged RAF of 4.209. It is billable for payment year 2026.
Coder answer: C78.80 is billable and maps to V28 HCC 17, Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- C78.80
- Description
- Secondary malignant neoplasm of unspecified digestive organ
- HCC (V28)
- HCC 17 — Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic
- RAF
- 4.209
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
Work C78.80 in the Code Book — tabular path, V28 RAF, and MEAT checklist →
MEAT Criteria for C78.80
For C78.80 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed C78.80 during that encounter, not just copy-forwarded from a problem list.
Coder workflow notes
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What This Code Means
C78.80 is the ICD-10-CM diagnosis code for secondary malignant neoplasm of unspecified digestive organ. Cancer that has spread to an unspecified digestive organ from a primary cancer elsewhere, when the exact organ cannot be determined. C78.80 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of ill-defined, other secondary and unspecified sites (c76-c80).
Under the CMS-HCC V28 risk adjustment model, C78.80 maps to Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic (HCC 17) with a community, non-dual, aged base RAF weight of 4.209. Under the older CMS-HCC V24 model, C78.80 maps to Metastatic Cancer and Acute Leukemia (HCC 8) with a community, non-dual, aged base RAF weight of 2.659. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Use this code only when the specific digestive organ site is unknown or unspecified in documentation. Because C78.80 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for C78.80 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when the specific digestive organ site is unknown or unspecified in documentation
- •Query the provider if possible to identify the specific organ involved for more precise coding
Clinical Significance
Secondary malignant neoplasm of an unspecified digestive organ indicates metastatic cancer to the gastrointestinal system without precise localization. This non-specific code should be avoided when documentation supports a more specific site. Using this code may signal insufficient clinical documentation and should prompt provider queries.
Documentation Requirements
- ✓Primary cancer site documented and coded separately
- ✓Best available description of the digestive organ involved
- ✓Imaging or pathological evidence of digestive system metastasis
- ✓Provider query documenting attempts to clarify the specific organ
- ✓Clinical presentation — symptoms suggestive of the specific digestive organ involved
Commonly Confused Codes
- •C78.4: Secondary malignant neoplasm of small intestine; use when small bowel is specified
- •C78.5: Secondary malignant neoplasm of large intestine and rectum; use when colon or rectum is specified
- •C78.7: Secondary malignant neoplasm of liver; liver is the most common digestive organ metastatic site
- •C78.89: Secondary malignant neoplasm of other digestive organs; use when a specific organ is identified but not covered by C78.4-C78.7