What is ICD-10 code C15.5?

C15.5 is the ICD-10-CM diagnosis code for Malignant neoplasm of lower third of esophagus. Cancer of the lower section of the esophagus, the tube that carries food from the throat to the stomach. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C15.5 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C15.5 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. C15.5 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. C15.5 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does C15.5 map to under V28?

C15.5 maps to CMS-HCC V28 HCC 20 (Lung and Other Severe Cancers). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM C15.5: Malignant neoplasm of lower

C15.5 maps to CMS-HCC V28 20. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software

ICD-10-CM Code View

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Code lookupC15.5

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of digestive organs (C15-C26)

C15.5

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Malignant neoplasm of lower third of esophagus

Cancer of the lower section of the esophagus, the tube that carries food from the throat to the stomach.

Buddy Insight

Malignant neoplasm of the lower third of the esophagus carries a high mortality rate and often presents at an advanced stage due to lack of early symptoms.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 20

Lung and Other Severe Cancers

Code-level coefficient reference

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 009

HHS-HCC 009 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 9

Lung and Other Severe Cancers

Code-level coefficient reference

RXHCC

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

C15Malignant neoplasm of esophagus C15.5Malignant neoplasm of lower third of esophagus

Inclusion Terms

Official

No inclusion terms are included in this display for C15.5. Check the code and parent instructions in the Code Book.

Excludes 2

Official

gastrointestinal stromal tumors (C49.A-)Inherited from C15-C26

Related Codes

Official

C15.3Malignant neoplasm of upper third of esophagus C15.4Malignant neoplasm of middle third of esophagus C15.8Malignant neoplasm of overlapping sites of esophagus C15.9Malignant neoplasm of esophagus, unspecified

Includes

Official

No Includes notes are included in this display for C15.5. Check the code and parent instructions in the Code Book.

Excludes 1

Official

malignant neoplasm of cardio-esophageal junction (C16.0)
Kaposi's sarcoma of gastrointestinal sites (C46.4)Inherited from C15-C26

Code First

Official

No Code First sequencing instructions are included in this display for C15.5. Check the code and parent instructions in the Code Book.

Use Additional

Official

code to identify:Inherited from C15
alcohol abuse and dependence (F10.-)Inherited from C15

Code Also

Official

No Code Also instructions are included in this display for C15.5. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Anatomical location confirmed as lower third of esophagus (approximately 32 cm to gastroesophageal junction)

Histological type (adenocarcinoma vs squamous cell carcinoma)

Stage of disease (TNM staging preferred)

Status of disease: active treatment, surveillance, or history of

MEAT Support

HCC Buddy guidance

Anatomical location confirmed as lower third of esophagus (approximately 32 cm to gastroesophageal junction)

Histological type (adenocarcinoma vs squamous cell carcinoma)

Stage of disease (TNM staging preferred)

Status of disease: active treatment, surveillance, or history of

Audit Caution

HCC Buddy guidance

Coding gastroesophageal junction tumors as lower esophagus when they should be coded as C16.0 (cardia) based on Siewert classification

Using C15.9 (unspecified) when documentation actually specifies the lower third location

Failing to distinguish between active malignancy and personal history (Z85.01) when cancer has been completely excised or is in remission

Not querying the provider when endoscopy report specifies distance from incisors but does not explicitly state 'lower third'

Common Mistakes

HCC Buddy guidance

C15.3 — Upper third of esophagus: different anatomical location with different surgical approach; verify endoscopy or imaging reports for exact location

C15.4 — Middle third of esophagus: adjacent segment; confirm documentation specifies lower third specifically

C16.0 — Malignant neoplasm of cardia: tumors at the gastroesophageal junction may be classified as either esophageal or gastric; Siewert classification helps determine correct code

C15.8 — Overlapping sites of esophagus: use when tumor spans multiple esophageal segments rather than being confined to lower third

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 C15.5 an HCC code?

Yes. C15.5 (Malignant neoplasm of lower third of esophagus) maps to HCC 20, Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 1.136. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: C15.5 is billable and maps to V28 HCC 20, Lung and Other Severe Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: C15.5
Description: Malignant neoplasm of lower third of esophagus
HCC (V28): HCC 20 — Lung and Other Severe Cancers
RAF reference coefficient: 1.136
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 20, Lung and Other Severe Cancers

1.136

ESRDHCC 9, Lung and Other Severe Cancers

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. 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 context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work C15.5 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C15.5

For C15.5, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

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

Coder workflow notes

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What This Code Means

C15.5 is the ICD-10-CM diagnosis code for malignant neoplasm of lower third of esophagus. Cancer of the lower section of the esophagus, the tube that carries food from the throat to the stomach. C15.5 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of digestive organs (c15-c26).

Under the CMS-HCC V28 risk adjustment model, C15.5 maps to Lung and Other Severe Cancers (HCC 20) with a source-labeled community, non-dual, aged reference coefficient of 1.136. No V24 mapping is shown for C15.5; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

The lower third of esophagus extends from approximately 32 cm to the gastroesophageal junction. For C15.5, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, and MEAT documentation criteria for C15.5 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•The lower third of esophagus extends from approximately 32 cm to the gastroesophageal junction
•Verify documentation distinguishes lower third from gastroesophageal junction cancers (which may be coded as stomach cancer)

Clinical Significance

Malignant neoplasm of the lower third of the esophagus carries a high mortality rate and often presents at an advanced stage due to lack of early symptoms. This location is associated with Barrett esophagus and gastroesophageal reflux disease as precursor conditions, making it critical for risk adjustment to capture the full disease burden. Accurate coding ensures appropriate resource allocation for complex treatment regimens including neoadjuvant therapy and surgical resection.

Documentation Requirements

✓Anatomical location confirmed as lower third of esophagus (approximately 32 cm to gastroesophageal junction)
✓Histological type (adenocarcinoma vs squamous cell carcinoma)
✓Stage of disease (TNM staging preferred)
✓Status of disease: active treatment, surveillance, or history of
✓Any associated Barrett esophagus or gastroesophageal reflux disease history

Excludes 1, Do NOT code together

malignant neoplasm of cardio-esophageal junction (C16.0)

Commonly Confused Codes

•C15.3: Upper third of esophagus: different anatomical location with different surgical approach; verify endoscopy or imaging reports for exact location
•C15.4: Middle third of esophagus: adjacent segment; confirm documentation specifies lower third specifically
•C16.0: Malignant neoplasm of cardia: tumors at the gastroesophageal junction may be classified as either esophageal or gastric; Siewert classification helps determine correct code
•C15.8: Overlapping sites of esophagus: use when tumor spans multiple esophageal segments rather than being confined to lower third