The authors note that the American Thyroid Association recommends total thyroidectomy for tumors larger than 1 cm, reserving lobectomy for smaller tumors with no extrathyroidal spread or nodal involvement. However, “questions persist,” write Dr. Abie H. Mendelsohn, at the University of California, Los Angeles, and colleagues.
For the current study, they used the Surveillance, Epidemiology, and End Results Program database to look at outcomes in 22,724 patients with papillary thyroid cancer who underwent surgery between 1988 and 2001.
While 16760 patients had a total thyroidectomy, 5964 patients were treated by lobectomy. The investigators find it “noteworthy” that 534 of the lobectomy patients had advanced-stage tumors.
Just under half the patients (10,978) also had radiation therapy. In most case this was in the form of radioactive iodine, but 547 were treated by external beam radiation.
Over a median follow-up of 9.1 years, 2138 subjects died, 471 of them from thyroid cancer
On multivariate analysis, increasing tumor size was associated with progressively worse outcomes: the hazard ratios for poor overall survival and poor disease-specific survival were 1.07 and 1.56, respectively. Similarly, aggressive tumor spread, positive lymph nodes and advanced age were all associated with worse outcomes.
“Surprisingly,” the researchers report, “although controlling for the remaining variables, including tumor size, the surgical groups of lobectomy and thyroidectomy did not reveal any differences in overall survival or disease specific survival.”
With external beam radiation compared to no radiation, the hazard ratio for worse overall survival was 1.71 and for worse disease-specific survival it was 4.48 (p<0.001 for both). The authors suggest this probably reflects the fact that many patients receiving external beam therapy may have already developed untreatable disease.
Dr. Mendelsohn and colleagues conclude, “The results of our study compel us to reinvestigate the current papillary thyroid cancer surgical recommendations of total thyroidectomy based on tumor size because this may not affect survival across all populations.”
Furthermore, they add, “The current use of external beam radiation therapy for the treatment of papillary thyroid cancer should be reexamined.”
Arch Otolaryngol Head Neck Surg 2010; 136:1055-1061.