KEYTRUDA FOR ADVANCED MSI-H/dMMR CANCERS

The following codes as of September 2023 are provided as a reference and may be relevant when billing for KEYTRUDA and its administration. Consult the relevant manual and/or other guidelines for a description of each code to determine the appropriateness of its use and for information on additional codes. Diagnosis codes should be selected only by a health care professional. You are solely responsible for determining the appropriate codes and for any action you take in billing.

When submitting a claim for KEYTRUDA, always verify coding requirements with the relevant payer. Coding requirements may vary by insurer or plan; please refer to the payer-specific policies to understand what may be covered.

Check with the relevant payer regarding guidance on which diagnoses they will recognize and the applicability of secondary codes. Health care professionals are solely responsible for selecting codes that appropriately reflect the patient’s diagnosis, the services rendered, and the applicable payers’ guidelines.

Providers should document the diagnosis with a sufficiently high degree of specificity based on the information available to enable the identification of the most appropriate code. Although CMS has said that an unspecified code may be appropriate in some cases, CMS has advised that you should always code with as much specificity as possible consistent with the clinical documentation.

Merck and its agents make no warranties concerning the accuracy or appropriateness of this information for your particular use given the frequent changes in public and private payer billing. Merck cautions that payer-coding requirements vary and can frequently change, so it is important to regularly check with each payer or, where applicable, the Medicare Administrative Contractor as to payer-specific requirements. The use of this information does not guarantee payment or that any payment received will cover your costs.

Indication

KEYTRUDA is indicated for the treatment of adult and pediatric patients with unresectable or metastatic microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) solid tumors, as determined by an FDA-approved test, that have progressed following prior treatment and who have no satisfactory alternative treatment options.

FDA-Approved Dosing

The FDA-approved dose of KEYTRUDA in adults is either 200 mg administered after dilution as an intravenous infusion over 30 minutes every 3 weeks or 400 mg administered after dilution as an intravenous infusion over 30 minutes every 6 weeks, until disease progression, unacceptable toxicity, or up to 24 months.

The FDA-approved dose of KEYTRUDA in pediatric patients is 2 mg/kg (up to a maximum of 200 mg), administered after dilution as an intravenous infusion over 30 minutes every 3 weeks until disease progression or unacceptable toxicity, or up to 24 months.

See full Prescribing Information for preparation and administration instructions and dosage modifications for adverse reactions.

Possible relevant diagnosis codes for MSI-H/dMMR cancer

Learn more about each diagnosis code and descriptor by selecting from the series options below.

When assigning ICD-10-CM for MSI-H/dMMR advanced tumors treated with KEYTRUDA, identify the appropriate ICD-10-CM category for the advanced malignant neoplasm of the body part under treatment and select the code based on the specific site. For example: C18.6 malignant neoplasm of descending colon.

 

C18: Malignant Neoplasm of Colon4

The C18 series excludes malignant carcinoid tumors of the colon; C18.7 excludes malignant neoplasm of rectosigmoid junction

ICD-10-CM CODE DESCRIPTOR
C18.0 Malignant neoplasm of cecum
  • Malignant neoplasm of ileocecal valve
C18.1 Malignant neoplasm of appendix
C18.2 Malignant neoplasm of ascending colon
C18.3 Malignant neoplasm of hepatic flexure
C18.4 Malignant neoplasm of transverse colon
C18.5 Malignant neoplasm of splenic flexure
C18.6 Malignant neoplasm of descending colon
C18.7 Malignant neoplasm of sigmoid colon
  • Malignant neoplasm of sigmoid (flexure)
  • Excludes: malignant neoplasm of rectosigmoid junction (C19)
C18.8 Malignant neoplasm of overlapping sites of colon
C18.9 Malignant neoplasm of colon, unspecified
  • Malignant neoplasm of large intestine not otherwise specified

C19: Malignant Neoplasm of Rectosigmoid Junction4

The C19 series excludes malignant carcinoid tumors of the colon

ICD-10-CM CODE DESCRIPTOR
C19 Malignant neoplasm of rectosigmoid junction
  • Malignant neoplasm of colon with rectum
  • Malignant neoplasm of rectosigmoid (colon)
  • Excludes: malignant carcinoid tumors of the colon (C7A.02-)

C20: Malignant Neoplasm of Rectum4

The C20 series excludes malignant carcinoid tumor of the rectum

ICD-10-CM CODE DESCRIPTOR
C20 Malignant neoplasm of rectum
  • Malignant neoplasm of rectal ampulla
  • Excludes: malignant carcinoid tumor of the rectum (C7A.026)

C21: Malignant Neoplasm of Anus and Anal Canal4

The C21 series:

  • Excludes: malignant carcinoid tumors of the colon, malignant melanoma of anal margin, malignant melanoma of anal skin, malignant melanoma of perianal skin, other and unspecified malignant neoplasm of anal margin, other and unspecified malignant neoplasm of anal skin, other and unspecified malignant neoplasm of perianal skin
ICD-10-CM CODE DESCRIPTOR
C21.8 Malignant neoplasm of overlapping sites of rectum, anus and anal canal
  • Malignant neoplasm of anorectal junction
  • Malignant neoplasm of anorectum
  • Primary malignant neoplasm of two or more contiguous sites of rectum, anus, and anal canal