Patients with intermediate-risk papillary thyroid cancer and lymph node metastasis show no significant increase in tumor recurrence when undergoing lobectomy compared with a total thyroidectomy, new research shows.
“Results of this cohort study suggest that patients with ipsilateral clinical lateral neck metastasis (cN1b) papillary thyroid cancer who underwent lobectomy exhibited recurrence-free survival rates similar to those who underwent total thyroidectomy after controlling for major prognostic factors,” the authors conclude in the study published online in JAMA Surgery.
“These findings suggest that cN1b alone should not be an absolute indication for total thyroidectomy,” they note.
The study, involving the largest cohort to date to compare patients with intermediate-risk papillary thyroid cancer treated with lobectomy versus total thyroidectomy, “challenged the current guidelines and pushed the boundary of limited surgical treatment even further,” say Michelle B. Mulder, MD, and Quan-Yang Duh, MD, of the department of surgery, University of California, San Francisco, in an accompanying editorial.
“It can be a game changer if confirmed by future prospective and multicenter studies,” they add.
Guidelines still recommend total thyroidectomy with subsequent RAI
While lower-intensity treatment options, with a lower risk of complications, have gained favor in the treatment of low-risk papillary thyroid cancer, guidelines still recommend the consideration of total thyroidectomy and subsequent radioactive iodine ablation (RAI) for intermediate-risk cancers because of the higher chance of recurrence, particularly among those with clinically positive nodes.
However, data on the superiority of a total thyroidectomy, with or without RAI, versus lobectomy is inconsistent, prompting first author Siyuan Xu, MD, of the department of head and neck surgical oncology, National Cancer Center, Beijing, and colleagues to compare the risk of recurrence with the two approaches.
For the study, patients with intermediate-risk papillary thyroid cancer treated at the Chinese Academy of Medical Sciences Cancer Hospital in Beijing between January 2000 and December 2017, who had a lobectomy or total thyroidectomy, were paired 1:1 in a propensity score matching analysis.
Other than treatment type, the 265 pairs of patients were matched based on all other potential prognostic factors, including age, sex, primary tumor size, minor extrathyroidal extension, multifocality, number of lymph node metastases, and lymph node ratio.
Participants were a mean age of 37 years and 66% were female.
With a median follow-up of 60 months in the lobectomy group and 58 months in the total thyroidectomy group, structural recurrences occurred in 7.9% (21) and 6.4% (17) of patients, respectively, which was not significantly different.
The primary endpoint, 5-year rate of recurrence-free survival, was also not significantly different between the lobectomy (92.3%) and total thyroidectomy groups (93.7%) (adjusted hazard ratio, 1.10; P = .77).
In a further stratified analysis of patients treated with total thyroidectomy along with RAI (n = 75), the lack of a significant difference in recurrence-free survival versus lobectomy remained (aHR, 0.59; P = .46).
The results were similar in unadjusted as well as adjusted analyses, and a power analysis indicated that the study had a 90% power to detect a more than 4.9% difference in recurrence-free survival.
“Given the lower complication rate of lobectomy, a maximal 4.9% recurrence-free survival difference is acceptable, which enhances the reliability of the study results,” the authors say.
They conclude that “our findings call into question whether cN1b alone [ipsilateral clinical lateral neck metastasis papillary thyroid cancer] should be an absolute determinant for deciding the optimal extent of thyroid surgery for papillary thyroid cancer.”