Summary & Overview
HCPCS G9104: Gastric Cancer (Adenocarcinoma) Disease Status, Staging in Progress
HCPCS Level II code G9104 identifies a disease-status reporting item specific to gastric cancer when adenocarcinoma is the predominant cell type and the extent of disease is unknown, staging is in progress, or not listed. The code is intended for use within a Medicare-approved demonstration project and captures the clinical status rather than a therapeutic intervention. Nationally, clear classification of disease-status codes like G9104 supports data collection for staging, outcomes measurement, and demonstration-program evaluation.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find context on clinical use and settings for G9104, how it fits into oncology care workflows, and where it applies in staging and reporting. The publication outlines expected service types and typical sites of service, clarifies the demonstration-project purpose of the code, and identifies common modifiers and other billing elements provided in the input. Policy context and implications for national reporting and claims classification are discussed to inform administrators, coders, and analysts.
Data not provided in the input (such as associated taxonomies, specific ICD-10 mappings, related codes, and payer-specific coverage rules) are noted as unavailable in the input and are not fabricated.
Billing Code Overview
HCPCS Level II code G9104 denotes oncology disease status reporting for gastric cancer, limited to adenocarcinoma as the predominant cell type, where the extent of disease is unknown, staging is in progress, or not listed. This code is designated for use in a Medicare-approved demonstration project and is specific to reporting disease status rather than treatment procedures.
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Service type: Disease status reporting / oncology diagnostic staging activity
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Typical site of service: Oncology clinic, hospital outpatient setting, or other clinical site where staging evaluation and disease-status assessment are performed
Clinical & Coding Specifications
Clinical Context
A 64-year-old patient with progressive epigastric pain, unintended weight loss, and iron-deficiency anemia is referred to a tertiary oncology center after endoscopic biopsy identified gastric adenocarcinoma. Diagnostic workup is incomplete: cross-sectional imaging and diagnostic laparoscopy scheduled, and pathologic subtyping confirms adenocarcinoma as the predominant histology. During a Medicare-approved demonstration project, the oncology team documents disease status as "extent of disease unknown, staging in progress, or not listed" and bills G9104 to indicate oncology disease status reporting for gastric adenocarcinoma. The clinical workflow includes initial consultation with a medical oncologist and surgical oncologist, coordination of CT chest/abdomen/pelvis, endoscopic ultrasound for local staging, and possible diagnostic laparoscopy to evaluate peritoneal spread. Oncology multidisciplinary conference records disease status as pending staging; documentation includes tumor histology, planned staging procedures, and anticipated neoadjuvant therapy decisions contingent on staging results.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
00 | No modifier; standard service | Assign when no modifier applies and service provided as usual |