Table 1.
Patients characteristics
| Variable | Whole cohort N (%) | RAI ablation N (%) | Without RAI ablation N (%) | P value* |
|---|---|---|---|---|
| Total patients | 326/1192 (27.4 %) | 182/326 (55.8) | 144/326 (44.2) | 0.06 |
| Age (years) | 42.6 (18–76) SD ±11.6 | 43.2 (18–76) SD ± 12.4 | 41.8 (19–71) SD ± 10.2 | |
| ≤45 years | 201 (61.7) | 110 (60.4) | 94 (65.3) | 0.81 |
| ≥45 years | 125 (38.3) | 72 (39.6) | 50 (34.7) | |
| Gender | ||||
| Female | 271 (83.1) | 146 (80.2) | 125 (86.8) | 0.06 |
| Male | 55 (16.9) | 36 (19.8) | 19 (13.2) | |
| Female to male ratio | 4.9 | 4.0 | 6.5 | |
| Type of surgery | ||||
| Total thyroidectomy | 299 (91.7) | 182 (100) | 117 (81.3) | 0.04 |
| Hemi-thyroidectomy | 27 (8.3) | - | 27 (18.7) | |
| Lymph node surgery | ||||
| Central neck dissection | 88 (27.0) | 54 (29.7) | 34 (23.6) | |
| Lateral neck dissection | 18 (5.5) | 9 (4.9) | 9 (6.3) | 0.9 |
| Sampling | 55 (16.9) | 25 (13.7) | 30 (20.8) | |
| None | 165 (50.6) | 94 (51.7) | 71 (49.3) | |
| Mean size (cm) | 0.61 (0.1–1.0) ± 0.24 | 0.72 (0.2–1.0) ± 0.21 | 0.44 (0.1–0.9) ± 0.2 | |
| ≤0.5 cm | 161 (49.4) | 50 (27.5) | 111 (77.1) | <0.0001 |
| ≥0.5 cm | 165 (50.6) | 132 (72.5) | 33 (22.9) | |
| Histopathologic variants | ||||
| Classic | 265 (81.3) | 143 (78.6) | 122 (84.7) | |
| Follicular | 41 (12.6) | 21 (11.5) | 20 (13.9) | |
| Hurthle cell | 8 (2.5) | 6 (3.3) | 2 (1.4) | |
| Tall cell | 11 (3.4) | 11 (6.0) | - | 0.001 |
| Sclerosing | 1 (0.3) | 1 (0.5) | - | |
| Multifocal | ||||
| Yes | 125 (38.3) | 122 (67.1) | 3 (2.1) | <0.0001 |
| No | 201 (61.7) | 60 (32.9) | 141 (97.9) | |
| ETE | ||||
| Yes | 62 (19.0) | 57 (31.3) | 5 (3.5) | <0.0001 |
| No | 264 (81.0) | 125 (68.7) | 139 (96.5) | |
| LVSI | ||||
| Yes | 55 (16.9) | 49 (26.9) | 6 (4.2) | <0.0001 |
| No | 271 (83.1) | 133 (73.1) | 138 (95.8) | |
| Surgical margins | ||||
| Positive | 35 (10.7) | 30 (16.5) | 5 (3.5) | <0.0001 |
| Negative | 291 (89.3) | 152 (83.5) | 139 (96.5) | |
| Lymph node metastasis | ||||
| Yes | 42 (12.9) | 42 (23.1) | - | <0.0001 |
| N1a | 34 (73.8) | 34 (73.8) | ||
| N1b | 8 (19.2) | 8 (19.2) | ||
| No | 284 (87.1) | 140 (76.9) | 144 (100) | |
| Background thyroid tissue | ||||
| Normal | 98 (30.1) | 47 (25.8) | 51 (35.4) | |
| Multi-nodular goiter | 106 (32.5) | 60 (32.9) | 46 (31.9) | |
| Lymphocytic thyroiditis/Hashimotos’ thyroiditis | 122 (37.5) | 75 (41.3) | 47 (32.6) | 0.052 |
| Distant Metastasis at presentation | 3 (0.9) | 3 (1.65) | - | <0.0001 |
| AJCC staging | ||||
| I | 217 (66.5) | 73 (40.1) | 139 (96.5) | |
| II | - | - | - | |
| III | 96 (29.5) | 96 (52.6) | 5 (3.5) | <0.0001 |
| IVA | 10 (3.1) | 10 (5.6) | - | |
| IVB | - | - | - | |
| IVC | 3 (0.9) | 3 (1.7) | - | |
| Mean postoperative TG (ng/ml) | 1.39 (0.1–42890) | 2.44 (0.1–42890) | 0.39 (0.1–8.9) | 0.62 |
| RAI dose | ||||
| 30 mCi | 50 (27.5) | - | <0.0001 | |
| 100 mCi | 85 (46.7) | - | ||
| 150-200 mCi | 47 (25.8) | - | ||
| RT to Neck | 2 (0.61) | 2 (1.1) | - | <0.0001 |
| Recurrences | ||||
| Locoregional | 13 (3.9) | 4 (2.2) | 9 (6.2) | <0.001 |
| Distant | 10 (3.1) | 4 (2.2) | 6 (4.2) | |
*P value pertaining to the variation in clinicopathological characteristics between two groups
RAI radioactive iodine 131, N number, SD standard deviation, ETE extra-thyroidal extension, LVSI lymphovascular space invasion, AJCC American joint committee on cancer, TG thyroglobulin, mCi millicurie, RT radiation therapy