| Virginia Cancer Specialists | Fairfax | VA | 130 |
| Texas Oncology - DFW | Dallas | TX | 77 |
| Texas Oncology - Northeast Texas | Tyler | TX | 57 |
| Rocky Mountain Cancer Centers-Midtown | Denver | CO | 56 |
| Rocky Mountain Cancer Centers-Penrose | Colorado Springs | CO | 50 |
| Rocky Mountain Cancer Centers-Sky Ridge | Lone Tree | CO | 50 |
| Rocky Mountain Cancer Centers-Aurora | Aurora | CO | 48 |
| Rocky Mountain Cancer Centers-Thornton | Thornton | CO | 34 |
| Rocky Mountain Cancer Centers-Littleton | Littleton | CO | 34 |
| Texas Oncology - San Antonio | San Antonio | TX | 34 |
| Texas Oncology - Central/South Texas | Austin | TX | 34 |
| Rocky Mountain Cancer Centers-Lakewood | Lakewood | CO | 33 |
| Rocky Mountain Cancer Centers-Rose | Denver | CO | 31 |
| Texas Oncology Central/South | Austin | TX | 31 |
| Columbus Oncology and Hematology Associates Inc | Columbus | OH | 30 |
| Rocky Mountain Cancer Centers-Longmont | Longmont | CO | 29 |
| US Oncology Investigational Product Center (IPC) | Irving | TX | 29 |
| Rocky Mountain Cancer Centers-Boulder | Boulder | CO | 28 |
| Texas Oncology - Gulf Coast | The Woodlands | TX | 28 |
| Rocky Mountain Cancer Centers - Centennial | Centennial | CO | 27 |
| Rocky Mountain Cancer Centers - Swedish | Englewood | CO | 26 |
| Columbus Oncology and Hematology Associates | Dublin | OH | 25 |
| Texas Oncology - DFW | Fort Worth | TX | 25 |
| Texas Oncology - Central South | Austin | TX | 20 |
| Texas Oncology - Gulf Coast | Webster | TX | 15 |
| Texas Oncology - West Texas | Abilene | TX | 14 |
| Texas Oncology - Gulf Coast | Sugar Land | TX | 14 |
| Texas Oncology - Northeast Texas | Denison | TX | 12 |
| Texas Oncology - Northeast Texas | Flower Mound | TX | 12 |
| Texas Oncology - Central South | Austin | TX | 12 |
| Texas Oncology - Gulf Coast | Houston | TX | 11 |
| Texas Oncology - Central/South Texas | McAllen | TX | 11 |
| Texas Oncology-Bedford | Bedford | TX | 10 |
| Texas Oncology - DFW | Dallas | TX | 10 |
| Texas Oncology - Gulf Coast | Beaumont | TX | 9 |
| Texas Oncology - West Texas | Amarillo | TX | 9 |
| Texas Oncology - Northeast Texas | Denton | TX | 9 |
| Texas Oncology - Northeast Texas | Longview | TX | 9 |
| Texas Oncology - San Antonio | San Antonio | TX | 9 |
| Texas Oncology - West Texas | El Paso | TX | 9 |
| Texas Oncology - Central South | Waco | TX | 9 |
| Texas Oncology-Gulf Coast | Pearland | TX | 8 |
| Texas Oncology | Dallas | TX | 8 |
| Texas Oncology - DFW | Grapevine | TX | 8 |
| Texas Oncology- Central South | Weslaco | TX | 8 |
| Virginia Cancer Specialists, PC | Arlington | VA | 8 |
| Texas Oncology - Central South | Harlingen | TX | 8 |
| Texas Oncology - Northeast Texas | Palestine | TX | 7 |
| Rocky Mountain Cancer Centers, LLP | Boulder | CO | 7 |
| Texas Oncology - Plano East | Plano | TX | 7 |
| Virginia Cancer Specialists, PC | Manassas | VA | 7 |
| Texas Oncology - DFW | Dallas | TX | 7 |
| Rocky Mountain Cancer Centers, LLP | Longmont | CO | 6 |
| Rocky Mountain Cancer Centers, LLP | Pueblo | CO | 6 |
| Texas Oncology-Northeast Texas | Allen | TX | 6 |
| Texas Oncology - Northeast Texas | McKinney | TX | 6 |
| Texas Oncology Plano West | Plano | TX | 6 |
| Rocky Mountain Cancer Centers - Pueblo | Pueblo | CO | 5 |
| Rocky Mountain Cancer Centers-Parker | Parker | CO | 5 |
| Texas Oncology - Gulf Coast | Houston | TX | 5 |
| Texas Oncology - Northeast Texas | Paris | TX | 5 |
| Rocky Mountain Cancer Centers, LLP | Colorado Springs | CO | 4 |
| Texas Oncology - Northeast Texas | Lewisville | TX | 4 |
| Texas Oncology - West Texas | Wichita Falls | TX | 4 |
| Virginia Cancer Specialists, PC | Reston | VA | 4 |
| Texas Oncology - San Antonio | New Braunfels | TX | 4 |
| Texas Oncology - DFW | Arlington | TX | 4 |
| Texas Oncology - DFW | Dallas | TX | 4 |
| Texas Oncology - Gulf Coast | Houston | TX | 4 |
| Texas Oncology - San Antonio | Fredericksburg | TX | 4 |
| Texas Oncology - San Antonio | San Antonio | TX | 4 |
| Texas Oncology - West Texas | Odessa | TX | 4 |
| Texas Oncology - DFW | Dallas | TX | 3 |
| USO - US Oncology Research Network | Nashville | TN | 3 |
| Texas Oncology | San Antonio | TX | 3 |
| Northwest Cancer Specialist, Pc(Us Oncology Research) | Vancouver | WA | 2 |
| Texas Oncology - DFW | Arlington | TX | 2 |
| Texas Oncology - Gulf Coast | Humble | TX | 2 |
| Texas Oncology - West Texas | El Paso | TX | 2 |
| Texas Oncology - West Texas | El Paso | TX | 2 |
| Texas Oncology - West Texas | Midland | TX | 2 |
| Virginia Cancer Specialists, PC | Woodbridge | VA | 2 |
| Texas Oncology | Denton | TX | 2 |
| Texas Oncology-San Antonio | San Antonio | TX | 2 |
| Maryland Oncology Hematology - Independent of SCRI/ US Oncology | Columbia | MD | 1 |
| Rocky Mountain Cancer Centers | Boulder | CO | 1 |
| Rocky Mountain Cancer Centers, LLP | Lone Tree | CO | 1 |
| Rocky Mountain Cancer Centers, LLP | Pueblo | CO | 1 |
| SCRI - Texas Oncology Dallas | Dallas | TX | 1 |
| Sarah Cannon Research Institute - St. David's South Austin Medical Center / Texas Oncology South Austin | Austin | TX | 1 |
| Site 0135 - Rocky Mountain Cancer Centers | Lone Tree | CO | 1 |
| Texas Oncology | Houston | TX | 1 |
| Texas Oncology (Webster) - USOR | Houston | TX | 1 |
| Texas Oncology - Carrollton | Carrollton | TX | 1 |
| Texas Oncology - Plano West | Plano | TX | 1 |
| Texas Oncology - Webster | Webster | TX | 1 |
| Texas Oncology Austin Midtown | Round Rock | TX | 1 |
| Texas Oncology DFW | Bedford | TX | 1 |
| Texas Oncology, P.A. | Houston | TX | 1 |
| Texas Oncology, P.A. - Oncology | Tyler | TX | 1 |