Baseline Characteristics of All Patients, Disease-Specific Survivors, and Deceased Patients
| Characteristic | All patients (n = 198) | Survivors (n = 174) | Decedents (n = 24) | P |
| Number of RITs | ||||
| 1 | 71 (36%) | 65 (37%) | 6 (25%) | |
| 2–5 | 99 (50%) | 86 (49%) | 13 (54%) | |
| 6–9 | 22 (11%) | 19 (11%) | 3 (13%) | |
| ≥10 | 6 (3%) | 4 (2%) | 2 (8%) | 0.397 |
| Average | 3.0 | 2.9 | 4.0 | 0.361 |
| Range | 1–26 | 1–17 | 1–26 | |
| Follow-up period (y) | ||||
| Mean | 5.37 | 5.17 | 6.78 | 0.578 |
| Range | 0.14–31.74 | 1.13–26.84 | 0.14–31.74 | |
| Age at initial RIT | ||||
| Mean (y) | 54.0 | 52.8 | 62.5 | 0.009 |
| Range (y) | 7–84 | 7–83 | 48–84 | |
| <45 y old:≥45 y old (n) | 48:150 (24%:76%) | 48:126 (28%:72%) | 0:24 (0%:100%) | <0.001 |
| Male:female (n) | 77:121 (39%:61%) | 66:108 (38%:62%) | 11:13 (46%:54%) | 0.460 |
| Initial 131I-RIT dose (MBq) | ||||
| Mean | 3,770.3 | 3,740.7 | 3,988.6 | 0.150 |
| Range | 296–5,994 | 1,665–5,994 | 296–5,994 | |
| Pathology (PAC:FAC:other) | 164:28:6 (83%:14%:3%) | 144:24:6 (83%:14%:3%) | 20:4:0 (83%:17%:0%) | 0.644 |
| WBS uptake at initial RIT (n) | ||||
| Excellent: 0 | 117 (59%) | 105 (60%) | 12 (50%) | |
| Good: 1 | 28 (14%) | 26 (15%) | 2 (8%) | |
| Fair: 2 | 51 (26%) | 42 (24%) | 9 (38%) | |
| Poor: 3 | 2 (1%) | 1 (1%) | 1 (4%) | 0.245 |
| Metastasis extent at initial RIT (n) | ||||
| 1* | 47 (24%) | 47 (27%) | 0 (0%) | |
| 2† | 105 (53%) | 92 (53%) | 13 (54%) | |
| 3 or 4‡ | 46 (23%) | 35 (20%) | 11 (46%) | <0.001 |
| Total thyroidectomy to initial RIT | ||||
| Mean (y) | 2.56 | 2.35 | 4.08 | 0.029 |
| Range (y) | 0.07–30.98 | 0.07–27.87 | 0.11–30.98 | |
| <180 d:≥180 d (n) | 106:92 (54%:46%) | 99:75 (57%:43%) | 7:17 (30%:71%) | <0.001 |
| Previous surgery | ||||
| Hemithyroidectomy/subtotal thyroidectomy | 59 (30%) | 54 (31%) | 5 (21%) | |
| No hemithyroidectomy/subtotal thyroidectomy | 124 (63%) | 110 (63%) | 14 (58%) | |
| Unknown | 15 (8%) | 10 (6%) | 5 (21%) | 0.060 |
| Years from hemithyroidectomy/subtotal to total | 6.3 | 5.9 | 10.2 | 0.878 |
| Therapy between initial thyroidectomy and initial RIT | ||||
| Local resection, lymph node resection, radiation, etc. | 42 (21%) | 39 (22%) | 3 (13%) | |
| No therapy | 142 (72%) | 125 (72%) | 17 (71%) | |
| Unknown | 14 (7%) | 10 (6%) | 4 (17%) | 0.146 |
| Longest blank period | ||||
| Treated within 180 d | 67 (34%) | 62 (36%) | 5 (21%) | |
| Treated within 180–364 d | 20 (10%) | 17 (10%) | 3 (13%) | |
| 1–2 y | 11 (6%) | 11 (6%) | 0 (0%) | |
| 2–3 y | 13 (7%) | 12 (7%) | 1 (4%) | |
| ≥3 y | 73 (37%) | 62 (36%) | 11 (46%) | |
| Unknown | 14 (7%) | 10 (6%) | 4 (17%) | 0.152 |
| Prethyroglobulin at initial RIT (ng/mL) | ||||
| Mean | 1,612 | 1,493 | 2,579 | <0.001 |
| Range | 3.0–46,386 | 3.0–464,386 | 160.4–10,109 | |
| Peak thyroglobulin at initial RIT (ng/mL) | ||||
| Mean | 7,667 | 7,415 | 10,001 | <0.001 |
| Range | 0.1–232,453 | 0.1–232,453 | 543–36,086 | |
| Postthyroglobulin at initial RIT (ng/mL) | ||||
| Mean | 1,178 | 1,130 | 1,616 | <0.001 |
| Range | 0.1–34,461 | 0.1–34,461 | 40.8–9,365 |