COLORADO SPRINGS — Total thyroidectomy results in fewer recurrences and better survival than lobectomy for patients with papillary thyroid cancer of at least 1 cm, Dr. Karl Y. Bilimoria said at the annual meeting of the American Surgical Association.
For papillary thyroid cancer (PTC) smaller than 1 cm, however, the extent of surgery doesn't affect outcomes, added Dr. Bilimoria of Northwestern University, Chicago.
He presented an analysis of outcomes in 52,173 patients who had surgery for PTC from 1985 to 1998 and were followed for a median of 8 years. The study's purpose was to learn if there is a tumor size threshold above which total thyroidectomy results in better outcomes than less extensive surgery.
The clinical relevance of this question arises from the rapidly increasing incidence of PTCs smaller than 2 cm, most of which are subclinical and are detected incidentally during imaging for other reasons. Thyroid cancer is diagnosed in approximately 35,000 Americans per year, and PTC is the most common pathologic type. The appropriate extent of surgery for PTC has been a matter of much controversy, Dr. Bilimoria explained.
The data on the more than 52,000 patients with PTC in his study came from the American College of Surgeons National Cancer Data Base, which collects patient information from 1,400 U.S. hospitals. The database captures an estimated 88% of all thyroid cancers occurring in the country.
Overall, 83% of the PTC patients underwent total thyroidectomy and 17% had lobectomy. Lobectomy was the predominant operation for tumors smaller than 1 cm. For tumors greater than 1 cm, a 60/40 total thyroidectomy/lobectomy split prevailed. Of total thyroidectomy patients who had their nodes tested, 34% had node-positive disease, as did 10.5% of lobectomy patients. Distant metastases were present in 2.4% of the total thyroidectomy group, and in 1.2% treated with lobectomy. Of the total thyroidectomy group, 56% received adjuvant radioiodine therapy.
Ten-year cancer recurrence risk and mortality rose with increasing tumor size. In a multivariate analysis controlling for tumor characteristics, patient demographics, and adjuvant therapy, patients with tumors of 1–2 cm had a highly significant 24% increased relative risk of recurrence and a 49% increased risk of death if they underwent lobectomy instead of total thyroidectomy.
In contrast, the relative risks of recurrence and mortality were similar in patients with a PTC smaller than 1 cm regardless of the type of surgery, Dr. Bilimoria continued.
Discussant Dr. Gerard M. Doherty hailed this report as “a very important study in clinical thyroidology that will probably answer this question once and for all.”
Current American Thyroid Association guidelines recommend total thyroidectomy for all PTCs 1 cm or more in size; however, the guidelines were based upon expert consensus. Dr. Bilimoria's report is the first adequately powered study to demonstrate improved survival with total thyroidectomy. As such it will undoubtedly strengthen the conclusions of upcoming guideline revisions, predicted Dr. Doherty, professor of surgery and head of the general surgery section at the University of Michigan, Ann Arbor.
Dr. Cord Sturgeon of Northwestern, senior coinvestigator in the study, estimated that routine total thyroidectomy in patients with PTC of at least 1 cm would result in an absolute 2% improvement in survival, compared with lobectomy.
The cost is a higher incidence of hypoparathyroidism, vocal fold paralysis, and other significant complications than with more conservative surgery. However, in this case the benefit clearly outweighs the risk, because the complication rate of total thyroidectomy in expert hands is only about 0.4%, he added.
All papers presented at the 127th annual meeting of the ASA are subsequently submitted to the Annals of Surgery for consideration.