Despite guideline revisions, total thyroidectomy often still needed in well-differentiated thyroid cancer

LAKE BUENA VISTA, Fla. — A large number of patients with well-differentiated thyroid cancer undergoing lobectomy under current guidelines would further require completion total thyroidectomy, according to retrospective study results presented at the International Thyroid Congress.

Total thyroidectomy (TT) has historically been recommended for patients with low-risk well-differentiated thyroid cancer and tumors at least 1 cm in size. However, recent National Comprehensive Cancer Network recommendations have indicated that unilateral lobectomy may serve as a viable alternative for patients with tumors 1 cm to 4 cm in size, according to study background.

“A subset of patients undergoing lobectomy may be found to still have high-risk characteristics,” Wouter P. Kluijfhout, MD, research fellow in endocrine surgery at University of California, San Francisco, said during a presentation. “We sought to determine the likelihood of finding high-risk characteristics that would lead to the recommendation of TT [in patients without preoperatively known risk factors].”

The researchers retrospectively reviewed 1,000 patients with well-differentiated thyroid cancer 1 cm to 4 cm in size who underwent TT between January 2000 and January 2010. Patients with unfavorable risk characteristics — including grossly extrathyroidal extension on preoperative imaging, clinically apparent lymph node metastases or potential family history — were excluded.

The researchers evaluated pathology specimens from the cancerous lobe for features that would lead to a recommendation for TT based on current guidelines, including aggressive histology, vascular invasion, microscopic extrathyroidal extension, positive margins and any positive lymph nodes.

From the overall cohort, 287 patients (mean age, 45 years; 80% women) would have been eligible for lobectomy as an initial course of treatment. The researchers observed angio-invasion in 12% (n = 34) of patients from this cohort, extrathyroidal extension in 17% (n = 48) of patients, positive margins in 18% (n = 51) of patients, positive lymph nodes in 18% (n = 49) of patients, and aggressive tall cell variant histology in one patient.

Completion TT would have been recommended for 43% (n = 122) who met eligibility criteria for lobectomy under current guidelines. Even among patients with smaller (1-2 cm) cancers, completion TT still would have been recommended in 36% (n = 52) of cases.

“We have shown that a large number of patients eligible for lobectomy present with high-risk characteristics,” Kluijfhout said. “We believe that it is important to both the patient and the clinician to estimate the risks associated with lobectomy vs. TT, and this study provides some estimate for the possible need for information in this area of treatment.” – by Cameron Kelsall

Reference:

Kluijfhout WP, et al. Short Oral Communication 50. Presented at: International Thyroid Congress; Oct. 18-23, 2015; Lake Buena Vista, Fla.

Disclosure: The researchers report no relevant financial disclosures.