Table 1.
Study Characteristics, Active Surveillance vs. Immediate Surgery
| Author study design country study period | Thyroid cancers included | Sample size | Duration of follow-up | Nonsurgical follow-up | Surgery | Age | Percent female | Tumor size | T classification |
|---|---|---|---|---|---|---|---|---|---|
| Ito et al. (19) and Ito et al. (20) [longer term follow-up from Ito et al. (21)] Prospective cohort study Japan (Kuma Hospital) 1993–2011 |
Papillary microcarcinoma (≤1 cm); for AS, no high-risk features (adjacent to trachea, possibly invading the recurrent laryngeal nerve, FNAB suggesting high-grade malignancy, highly suspicious for or confirmed lymph node metastasis in the lateral compartment); for immediate surgery, absence of high-risk features not specified | Total: 1395 AS: 340 Immediate surgery: 1055 |
AS: mean 76 months (range 1–198 months) Immediate surgery: mean 76 months (range 1–183 months) |
Ultrasonography once or twice yearly | Total or near-total thyroidectomy: 41% Subtotal thyroidectomy: 9.6% Lobectomy with isthmectomy: 46% Isthmectomy: 2.4% Partial lobectomy: 0.7% Complete radical lymph node resection: 51% Unilateral modified radical lymph node dissection: 38% Bilateral modified radical lymph node dissection: 2.2% No lymph node dissection: 8.9% |
AS: not reported Immediate surgery: mean 52.0 years |
AS: 92% Immediate surgery: 91% |
Not reported (all ≤1 cm) | All T1 (≤1 cm) |
| Jeon et al. (34) Cross-sectional South Korea 2016–2017 |
Papillary thyroid microcarcinoma (≤1 cm, Bethesda category 5 or 6) | Total: 191 AS: 43 Immediate surgery (lobectomy): 148 |
Cross-sectional; mean time from initial diagnosis 30 vs. 38 months | Not described | Lobectomy | AS: mean 50.3 years (SD 10.6) Lobectomy: mean 51.0 years (SD 10.4) |
AS: 67% Lobectomy: 85% |
Not reported (all ≤1 cm) | All T1 (≤1 cm) |
| Moon et al. (31) [earlier cohort reported in Kong et al. (22) and protocol reported in Moon et al. (25)] Prospective cohort study (MAeSTro) South Korea 2016–2020 |
Papillary thyroid microcarcinoma (<1 cm, Bethesda V or VI), without high-risk features (suspected major organ involvement, lymph node/distant metastasis, poorly differentiated histology, variant with poor prognosis) | Total: 1055 AS: 674 Immediate surgery: 381 |
Mean 24.2 months (SD 19.6) | Follow-up every 6 months for 2 years, then yearly with physical examination, high-resolution thyroid ultrasonography, and thyroid function test | Not described | AS: mean 48.8 years (SD 11.9) Immediate surgery: mean 45.7 years (SD 10.4) |
AS: 72% Immediate surgery: 80% |
AS: 5.7 mm (SD 1.6) Immediate surgery: 6.5 mm (SD 2.1) |
All T1 (<1 cm) |
| Nakamura et al. (35) [potential overlap with Ito et al. (19) and Ito et al. (20)] Cross-sectional Japan (Kuma Hospital) 2019 |
Papillary thyroid carcinoma (≤1 cm) with no high-risk features (e.g., nodal metastasis, significant extrathyroidal extension, high-grade malignancy on cytology, worrisome location [e.g. attachment to trachea or course of recurrent laryngeal nerve]) | Total 347 AS: 298 Immediate surgery: 49 |
AS: median 56 months (IQR 32–88) Immediate surgery: median 84 months (IQR 64–130) |
Not described | Hemithyroidectomy and paratracheal dissection: 35% Total thyroidectomy and central compartment neck dissection: 65% |
AS: 58.6 years (SD 12.5) Immediate surgery: 58.4 years (SD 13.1) |
AS: 89% Immediate surgery: 96% |
AS: 7 mm (IQR 5–8) Immediate surgery: 8 mm (IQR 7–9) |
All T1 (<1 cm) |
| Oda et al. (26) Sasaki et al. (33) (AS arm only) Cohort (appears retrospective) Japan (Kuma Hospital) 2005–2013 (Oda)/2017 (Sasaki) |
Low-risk papillary microcarcinoma (≤1 cm with no high-risk features [nodal or distant metastasis, macroscopic extrathyroidal extension, high-grade malignancy on cytology, evidence of progression, or other worrisome finding e.g., attachment to trachea or on course of recurrent laryngeal nerve]) | Total: 2153 AS: 1179 Surgery: 974 |
AS: median 47 months (range 12–116) Immediate surgery: median 47 months (range 12–116 months) |
Ultrasound, thyroid function tests, serum calcium 6 months after diagnosis then yearly; fiberoptic laryngoscopy for voice changes | Hemithyroidectomy and paratracheal dissection: 59% Total thyroidectomy and central compartment neck dissection: 41% |
AS: median 57 (ranged 15–88) Immediate surgery: median 55 (range 15–84) |
AS: 88% Surgery: 88% |
AS: median 7 mm (range 2–10) Immediate surgery: median 8 mm (range 3–10) |
All T1 (≤1 cm) |
| Rosario et al. (27) Prospective cohort study Brazil 2016–2019 |
Papillary thyroid carcinoma ≤1.2 cm, Bethesda category V or VI, without extrathyroidal invasion or lymph node metastasis, and not located near the recurrent laryngeal nerve | 77 (70 had at least 1 follow-up evaluation) | Median not reported, range 6 months to 3 years | Ultrasound every 6 months | Not reported | AS: median 52 years (range 23–81) Immediate surgery: median 51 years (range 25–78) |
AS: 79% Immediate surgery: 83% |
AS: ≤1 cm: 90% 1 to 1.2 cm: 10% Immediate surgery: ≤1 cm: 89% 1 to 1.2 cm: 11% |
All T1 (≤1.2 cm) |
| Sakai et al. (28) [longer-term follow-up from same T1a cohort as Sugitani et al. (29) adds T1b with surgical comparison group]; also, Fukuoka et al. (17) and Nagaoka et al. (32) (7.6-year follow-up, AS only) Prospective cohort study Japan (Cancer Institute Hospital) 1995–2016 |
Low-risk T1aN0M0 or T1bN0M0 papillary thyroid carcinoma | Total: 752 AS: 421 (360 T1a and 61 T1b) Immediate surgery (T1b): 331 |
Mean 7.4 to 7.9 years (range 0.5–25 years) | Palpation, ultrasonography, chest radiography every 6 or 12 months | Total thyroidectomy for bilateral lesions or autoimmune thyroid disease; otherwise lobectomy Central node dissection and selective lateral neck dissection |
AS: mean 53.9 (SD 12, T1a) and 54.4 (SD 10.7, T1b) Immediate surgery: mean 51.9 (SD 12.6, T1b) |
AS: 89% (T1a) and 77% (T1b) Immediate surgery: 84% (T1b) |
AS: 7.6 mm (SD 1.8, T1a) and 11.7 (SD 1.1, T1b) Immediate surgery: 14.5 mm (SD 2.8) |
All T1a or T1b |
AS, active surveillance; FNAB, fine needle aspiration biopsy; IQR, interquartile range; SD, standard deviation.