ICD-10-CM > Z00-Z99 > Z40-Z53 > Z51 > Z51.1 Z51.1 Encounter for antineoplastic chemotherapy and immunotherapy Non-Billable/Non-Specific Type 2 Excludes encounter for chemotherapy and immunotherapy for nonneoplastic condition - code to condition Codes Z51.11Encounter for antineoplastic chemotherapyZ51.12Encounter for antineoplastic immunotherapy