TABLE 5.
The top 20 keywords in terms of frequency in the research on the association of rare earth elements with cancer.
| Rank | Keywords | N | Rank | Keywords | N |
| 1 | Cancer | 948 | 11 | Cerium Oxide Nanoparticles | 231 |
| 2 | Nanoparticles | 502 | 12 | Toxicity | 225 |
| 3 | Therapy | 467 | 13 | Photodynamic therapy | 222 |
| 4 | Gadolinium | 341 | 14 | In vitro | 221 |
| 5 | Magnetic Resonance Imaging | 566 | 15 | Survival | 218 |
| 6 | Radioembolization | 281 | 16 | Oxidative stress | 217 |
| 7 | Cells | 257 | 17 | Hepatocellular-carcinoma | 210 |
| 8 | Contrast agents | 254 | 18 | Radiotherapy | 209 |
| 9 | In vivo | 244 | 19 | Drug-delivery | 202 |
| 10 | Luminescence | 240 | 20 | Chemotherapy | 201 |