2027 ICD-10-CM Diagnosis Code C16.9Malignant neoplasm of stomach, unspecified

ICD-10-CM Codes›C00–D49›C15-C26›C16

ICD-10-CM C16.9
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

C16.9 is a billable ICD-10-CM diagnosis code for malignant neoplasm of stomach, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 374 through 376. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 32 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Gastrointestinal cancers - stomach.

For Medicare Advantage risk adjustment, C16.9 maps to CMS-HCC Category 20 (Lung and Other Severe Cancers) under the V28 model, adding a risk factor of about 1.136 for a community, non-dual, aged beneficiary in payment year 2027.

Code Identity

ICD-10-CM Code
C16.9
Billable Status
Yes — Valid for Submission
Code Describes
Malignant neoplasm of stomach, unspecified
Short Description
Malignant neoplasm of stomach, unspecified
Same as the full description in the CMS dataset.
Parent Code
C16
Malignant neoplasm of stomach

Code Classification

ChapterC00–D49Neoplasms
SectionC15-C26Malignant neoplasms of digestive organs
CategoryC16Malignant neoplasm of stomach
This CodeC16.9Malignant neoplasm of stomach, unspecified

Medicare Risk Adjustment (HCC)Billing

C16.9 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.

CMS-HCC V28 Category (Payment Model)
HCC 20— Lung and Other Severe Cancers
Payment HCC · PY 2027 one of 233 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+1.136
community, non-dual, aged · ranges 0.672–1.214 across segments
Hierarchy
Superseded by HCC 17, HCC 18, and HCC 19
a more severe related category takes the payment when both are reported
Prior Model (CMS-HCC V24)
HCC 9
V24 retired V28 pays 100% of MA risk scores since PY 2026
Other CMS Models
PACE (CMS-HCC V22): HCC 9 · ESRD (V21): HCC 9 · ESRD (V24): HCC 9
ESRD V21 weights: 0.169 dialysis, 0.604–0.975 functioning graft · ESRD V24 weights: 0.181 dialysis, 0.770–1.226 functioning graft
Part D (RxHCC)
RxHCC 22 — Prostate, Breast, Bladder, and Other Cancers and Tumors
also risk-adjusts in the Part D prescription drug model (V08)

Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Adenocarcinoma of stomach
  • Carcinoma of stomach
  • Early gastric cancer
  • Epstein-Barr virus associated gastric carcinoma
  • Gastric adenocarcinoma and proximal polyposis of stomach
  • Gastric polyp
  • Gastric polyposis
  • HER2-positive gastric cancer
  • Hereditary diffuse carcinoma of stomach
  • Late gastric cancer
  • Leiomyosarcoma of stomach
  • Linitis plastica of stomach
  • Local recurrence of malignant neoplasm of stomach
  • Malignant neoplasm of stomach
  • Primary carcinoma of stomach
  • Primary carcinoma of stomach due to Epstein-Barr virus disease
  • Primary HER2-positive gastric cancer
  • Primary linitis plastica of stomach
  • Primary malignant mesenchymal neoplasm of stomach
  • Primary malignant neoplasm of stomach
  • Primary squamous cell carcinoma of stomach
  • Primary undifferentiated carcinoma of stomach
  • Squamous cell carcinoma of stomach
  • Undifferentiated carcinoma of stomach

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to C16.9: its own notes plus those printed at C16, block C15-C26, and Chapter 2. A note printed at a category, block or chapter applies to every code under it.

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Gastric cancer NOS

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Block C15-C26 Malignant neoplasms of digestive organs applies to 60 codes
  • Kaposi's sarcoma of gastrointestinal sites (C46.4)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From C16 Malignant neoplasm of stomach applies to 9 codes
  • malignant carcinoid tumor of the stomach (C7A.092)
From Block C15-C26 Malignant neoplasms of digestive organs applies to 60 codes
  • gastrointestinal stromal tumors (C49.A-)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From C16 Malignant neoplasm of stomach applies to 9 codes
  • code to identify:
  • alcohol abuse and dependence (F10.-)

Notes

General instructions on how these codes are used.

From Chapter 2 (C00-D49) Neoplasms applies to 1,730 codes
  • Functional activity
  • All neoplasms are classified in this chapter, whether they are functionally active or not. An additional code from Chapter 4 may be used, to identify functional activity associated with any neoplasm.
  • Morphology [Histology]
  • Chapter 2 classifies neoplasms primarily by site (topography), with broad groupings for behavior, malignant, in situ, benign, etc. The Table of Neoplasms should be used to identify the correct topography code. In a few cases, such as for malignant melanoma and certain neuroendocrine tumors, the morphology (histologic type) is included in the category and codes.
  • Primary malignant neoplasms overlapping site boundaries
  • A primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 ('overlapping lesion'), unless the combination is specifically indexed elsewhere. For multiple neoplasms of the same site that are not contiguous, such as tumors in different quadrants of the same breast, codes for each site should be assigned.
  • Malignant neoplasm of ectopic tissue
  • Malignant neoplasms of ectopic tissue are to be coded to the site mentioned, e.g., ectopic pancreatic malignant neoplasms are coded to pancreas, unspecified (C25.9).

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name C16.9, its category, or a range that includes it.

Applicable To 2

These notes mention C16.9.

  • Z85.028 Personal history of other malignant neoplasm of stomach
    Conditions classifiable to C16 names C16, which includes this code
  • Z80.0 Family history of malignant neoplasm of digestive organs
    Conditions classifiable to C15-C26 names C15-C26, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NEO013
Gastrointestinal cancers - stomach
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Linitis Plastica

    a condition where the stomach wall becomes thickened, rubbery and loses its ability to distend. the stomach assumes a leather bottle shape. it is most often seen in adenocarcinoma of the stomach. the term is often used synonymously with diffuse adenocarcinoma of the stomach.

Table of NeoplasmsClinical

Anatomical sites in the Table of Neoplasms that reference this code family.

SiteMalig.
Primary		Malig.
Secondary		Ca
in situ		BenignUncertainUnspec.
stomachC16.9C78.89D00.2D13.1D37.1D49.0
stomach › wall NECC16.9C78.89D00.2D13.1D37.1D49.0

Patient EducationClinical

Stomach Cancer

The stomach is an organ between the esophagus and the small intestine. It mixes food with stomach acid and helps digest protein. Stomach cancer mostly affects older people - two-thirds of people who have it are over age 65. Your risk of getting it is also higher if you:

The full article covers:

  • What is Stomach Cancer?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert C16.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
151.9 Malig neopl stomach NOS
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About C16.9Overview

What is the ICD-10 code for malignant neoplasm of stomach, unspecified?

The ICD-10-CM code for malignant neoplasm of stomach, unspecified is C16.9 (sometimes written as C169). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is C16.9 (Malignant neoplasm of stomach) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of stomach, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does C16.9 group to?

When malignant neoplasm of stomach, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 375, 374, 376, with relative weights from 0.8925 to 2.1101 depending on complications. Higher weights mean higher Medicare reimbursement.

Is C16.9 a CC or MCC?

CMS lists C16.9 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 32 closely related codes in its exclusion list.

Can C16.9 be reported with C46.4?

Not as a rule. The Excludes1 note at block C15-C26, which applies to C16.9, lists "Kaposi's sarcoma of gastrointestinal sites (C46.4)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).

What HCC is C16.9?

C16.9 (malignant neoplasm of stomach, unspecified) maps to CMS-HCC Category 20 (Lung and Other Severe Cancers), commonly written as HCC 20, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 9 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 22.

Does C16.9 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, C16.9 adds a risk adjustment factor of about 1.136 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.672 to 1.214 depending on the payment segment). A more severe related category (HCC 17, HCC 18, and HCC 19) supersedes it when both are reported. See the full factor table on the HCC 20 category page.