Table 1.
Characteristics of the Study and Control Cohorts at the Time of Primary Treatment
| Characteristica | Study cohort (n=220) | Controls (n=1020) |
|---|---|---|
| Sex | ||
| Male | 33 (15) | 207 (20.3) |
| Female | 187 (85) | 813 (79.7) |
| Median age at diagnosis, years (range) | 45.9 (12.5–84.1) | 44.0 (13.0–78.0) |
| Median tumor size, mm (range) | 12 (0.5–50)* | 15 (0.3–90) |
| Tumor focib | ||
| Unifocal | 140 (63.6) | 656 (64.3) |
| Multifocal | 80 (36.4) | 364 (35.7) |
| Unilateral | 162 (75.7) | 765 (75) |
| Bilateral | 52 (24.3) | 255 (25) |
| Extrathyroidal extension, % | ||
| No | 158 (71.8) | 776 (76) |
| Microscopic | 53 (24.1) | 244 (24) |
| Macroscopic | 9 (4.1)** | 0 (0) |
| Lymph node metastasesc | ||
| No | 157 (71.4) | 766 (75) |
| Yes | 63 (28.6) | 254 (25) |
| Distant metastasesd | ||
| No | 175 (95.1) | 869 (96.3) |
| Yes | 9 (4.9) | 33 (3.7) |
| Stage | ||
| I | 160 (72.7) | 753 (73.8) |
| II | 18 (8.2) | 82 (8) |
| III | 21 (9.6) | 117 (11.4) |
| IVa | 10 (4.5) | 41 (4) |
| IVc | 4 (1.8) | 15 (1.4) |
| Unknown | 7 (3.2) | 12 (1.2) |
| ATA risk | ||
| Low | 131 (59.5) | 625 (61.3) |
| Intermediate | 74 (33.6) | 362 (35.5) |
| High | 15 (6.9)* | 33 (3.2) |
| Radioiodine ablation | ||
| Yes | 184 (83.6) | 902 (88.4) |
| No | 36 (16.4) | 118 (11.6) |
Unless otherwise stated, results are reported as numbers (%) of patients in the study and control cohorts (TgAb-positive and TgAb-negative, respectively, at the first [1–12 month] posttreatment visit).
Primary tumor laterality was unknown for six TgAb-positive patients.
The group without evidence of lymph node metastases includes both patients who underwent neck dissection with no metastastic nodes at histology report (pN0) and patients who did not undergo neck dissection and who had no evidence of lymph node involvement at neck ultrasonography (cN0).
Data reported only for patients who had post-RRA 131I whole-body scan to assess distant sites (184/220 study patients, 902/1020 controls). N.B. All patients excluded from the analysis were classified as low risk, and none had clinically signs suggestive of extrathyroidal tumor spread.
p<0.05.
p<0.0001.
ATA, American Thyroid Association; RRA, radioiodine remnant ablation; TgAb, anti-thyroglobulin antibody.