Pathobiology of antineoplastic therapy in undifferentiated thyroid cancer

Use of radioiodine-131 scan to measure influence of surgical discipline, practice, and volume on residual thyroid tissue after total thyroidectomy for differentiated thyroid carcinoma

BACKGROUND

Our study's purpose is to determine the influence of surgical discipline, surgeon site, and volume on remnant thyroid tissue visualized on radioactive iodine-131 (I-131) scans after total thyroidectomy and I-131 ablation in patients with well-differentiated thyroid carcinomas.

METHODS

We retrospectively reviewed all cases of patients who received I-131 therapeutic ablation and postablation radioactive I-131 scans at our center after thyroidectomy to calculate the fraction of administered dose multiplied by 1000 (UDR1000).

RESULTS

The remnant thyroid tissue (ie, the UDR1000), between academic and community surgeons was 0.471 (±0.705) and 1.190 (±2.487), respectively (P = .001). The UDR1000 between otolaryngology-head and neck surgery and general surgery was 0.654 (±1.575) and 1.043 (±1.625), respectively (P = .159). The UDR1000 partitioned by patient frequencies of <10, 10 to 19, and ≥20 patients yielded 1.255 (±2.554), 0.926 (±2.084), and 0.467 (±0.721), respectively (P = .003).

CONCLUSION

Our study found statistically significant differences in residual thyroid tissue visualized on radioactive I-131 scans based on surgeon parameters.

Radioiodine-remnant ablation in low-risk differentiated thyroid cancer: pros

Differentiated thyroid carcinomas are typically treated with total thyroidectomy as initial therapy. Subsequent radioactive iodine (RAI) ablation destroys post-surgical thyroid remnants, can additionally provide adjuvant therapy of residual and metastatic thyroid cancers, and enhances the sensitivity and specificity of further diagnostic studies. There is current controversy regarding whether a large number of patients, broadly considered to have "low-risk" disease, should be provided RAI ablation. This is consequent to over-reliance on short-term studies, under-appreciation of the value of RAI remnant ablation, and inflation of the side effects of RAI therapy. A balanced assessment of all of these issues provides justification to utilize post-surgical radioiodine ablation, even in cases that are considered low risk on the basis of surgical findings.