ICD-10 Code C78 – Secondary malignant neoplasm of respiratory and digestive organs (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C78 – Secondary malignant neoplasm of respiratory and digestive organs
What it is
C78 identifies secondary, or metastatic, malignant tumors involving respiratory or digestive organs. Use it when cancer has spread from a primary site to these organ systems.
Clinical signs
Clinical features vary; refer to documentation. Common findings may include imaging or pathology evidence of metastatic disease in organs such as the lungs or gastrointestinal tract.
When to use this code
Use C78 when the record clearly states metastatic cancer to respiratory or digestive organs and no more specific subcode is documented. Code the primary malignancy separately when it is still relevant to the encounter.
Apply this code for confirmed secondary tumors, not for suspected spread. Check documentation for the exact metastatic site and whether a more specific ICD-10-CM code is available.
Do not use for
Do not use C78 for primary cancers arising in the lung, esophagus, stomach, bowel, or other digestive structures. Do not use it for uncertain findings without documented metastasis.
Coding tip
Review the pathology, imaging, and provider assessment to confirm metastatic involvement and select the most specific code available.