2026 ICD-10-CM Diagnosis Code C18Malignant neoplasm of colon

ICD-10-CM Codes›C00–D49›C15-C26›C18

ICD-10-CM C18
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

C18 is a non-billable ICD-10-CM category code for malignant neoplasm of colon, so it cannot be submitted on claims. Use a more specific code from this category instead, such as C18.0, C18.1, C18.2, and C18.3.

Code Identity

ICD-10-CM Code
C18
Billable Status
No — Non-Billable Category
Code Describes
Malignant neoplasm of colon
Short Description
Malignant neoplasm of colon
Same as the full description in the CMS dataset.
Chapter
C15-C26
Malignant neoplasms of digestive organs

Code Classification

ChapterC00–D49Neoplasms
SectionC15-C26Malignant neoplasms of digestive organs
CategoryC18Malignant neoplasm of colon
This CodeC18Malignant neoplasm of colon

Specific Coding for Malignant neoplasm of colonOverview

Non-specific codes like C18 require more characters. Use one of these billable codes instead:

  • Use C18.0 for Malignant neoplasm of cecum

  • Use C18.1 for Malignant neoplasm of appendix

  • Use C18.2 for Malignant neoplasm of ascending colon

  • Use C18.3 for Malignant neoplasm of hepatic flexure

  • Use C18.4 for Malignant neoplasm of transverse colon

  • Use C18.5 for Malignant neoplasm of splenic flexure

  • Use C18.6 for Malignant neoplasm of descending colon

  • Use C18.7 for Malignant neoplasm of sigmoid colon

  • Use C18.8 for Malignant neoplasm of overlapping sites of colon

  • Use C18.9 for Malignant neoplasm of colon, unspecified

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Type 1 Excludes

  • malignant carcinoid tumors of the colon C7A.02

Patient EducationClinical

Colorectal Cancer

Colorectal cancer is cancer that develops in the tissues of the colon or rectum. Your colon and rectum are part of your digestive system:

The full article covers:

  • What is colorectal cancer?
  • What causes colorectal cancer?
  • Who is more likely to develop colorectal cancer?
  • What are the symptoms of colorectal cancer?
  • What is screening for colorectal cancer and who needs it?
  • How is colorectal cancer diagnosed?
  • What are the treatments for colorectal cancer?
  • Can colorectal cancer be prevented?

Read the full article at MedlinePlus

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

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About C18Overview

Is C18 (Malignant neoplasm of colon) a billable code?

No. This is a category header that groups the codes for malignant neoplasm of colon, and headers cannot be submitted on claims. Claims for malignant neoplasm of colon need a more specific code from this category, such as C18.0, C18.1, and C18.2.