Researchers advise that preoperative screening with ultrasonography should be a standard part of the initial operative treatment for papillary thyroid cancer (PTC).
The scientists, from the Mayo Clinic in Rochester, Minnesota, USA, make this suggestion based on the results of their study in which they hypothesized that preoperative ultrasonography would increase detection and assessment of lymph node metastases (LNMs) in patients with PTC.
Reporting in the Archives of Surgery, they explain that recurrent cervical LNMs have been identified in 30-40% of patients following surgery for PTC.
"Because most of these recurrences could be discovered and treated to apparent extinction with one or more doses of radioactive iodine, they were largely dismissed as a minor issue," lead author Clive Grant and colleagues state.
"However, subsequent operations carried an associated 20% morbidity, mostly recurrent laryngeal nerve paralysis or hypoparathyroidism," they stress.
The investigators therefore recorded the outcome of 702 patients who were seen at their tertiary care center between 1999 and 2004, 486 of whom underwent initial surgical management and 216 underwent cervical reoperation for PTC. All individuals underwent reoperative ultrasonography.
Data showed that nonpalpable lateral jugular LNMs were detected by ultrasonography in 14.4% of the patients who underwent initial exploration.
Ultrasonography also identified nonpalpable lateral LNMs and LNMs in the central neck in 64.2% and 28.2% of reoperative patients, respectively.
Of note, ultrasonography results changed the course of the operation in 40.5% of the initial and 42.9% of the reoperative patients, regardless of whether the nodes were palpable or not, before surgery.
Ultrasonography showed 83.5% sensitivity, 97.7% specificity, and a positive predictive value of 88.8% for the detection of LNMs in the initial exploration patients, with corresponding values of 90.4%, 78.9%, and 93.9% in reoperative patients.
Reflecting on their findings, Grant et al caution that to rely on ultrasonography for the detection of LNMs requires highly skilled, dedicated, and intellectually competent ultrasonographers.
However, "adequate preoperative imaging with precise anatomical localization has become virtually mandatory in the surgical management of reoperative PTC patients," they add.
The team concludes: "Certainly ultrasonography is more sensitive and precise than any other modality in our experience."