| Abbreviation | Definition |
|---|---|
| IPOS | International Psycho-Oncology Society |
| IPSO | International Society of Pediatric Surgical Oncology |
| IPSS | International Prostate Symptom Score |
| IPT | Inflammatory Pseudotumor |
| IPTR | International Pancreas Traansplant Registry |
| IROC | Imaging and Radiation Oncology Core |
| ISBP | International Society of Breast Pathology |
| ISCO | Idaho Society of Clinical Oncology |
| ISCO | International Society for Cellular Oncology |
| ISOG | In Silico Oncology Group |
| ISOO | International Society of Ocular Oncology |
| ISOO | International Society of Oral Oncology |
| ISRO | Iranian Society Of Radiation Oncology |
| ITOG | International Thyroid Oncology Group |
| ITU | Intensive Therapy Unit |
| IU | International Units |
| IUO | Institute for Urologic Oncology |
| IUO | Institute of Urologic Oncology |
| IV | Intravenous - into a vein |
| IVP | IntraVenous Pyelogram |