| Abbreviation | Definition |
|---|---|
| OIB | Open Incisional Biopsy |
| OICO | Office of International Collaboration in Oncology |
| OIRO | Oxford Institute for Radiation Oncology |
| OKC | Odontogenic KeratoCyst |
| OMEA | Oncology Monitoring Excellence Academy |
| OMT | Optician Medical Technician |
| ONB | Olfactory NeuroBlastoma |
| ONC | oncologist |
| ONC | Oncology Nurse Certified |
| ONCOLOGY | Oncologist |
| OODP | Office of Oncology Drug Products |
| OOG | Ophthalmic Oncology Group |
| OORL | Oncology Outcomes Research Lab |
| OORL | Oncology Outcomes Research Laboratory |
| OOTF | Ophthalmic Oncology Task Force |
| OP | Oncotic Pressure |
| OPC | Out-Patient Care |
| ORCA | Oncology Resource Compliance Application |
| ORP | Oncology Research Program |
| OS | Osteogenic Sarcoma (bone tumors) |