Complications

Many of the data on complication rates in reoperation for WDTC come from small retrospective studies from single institutions . Roh and colleagues recently reported on 22 patients who underwent surgery for recurrent WDTC in the lateral neck. This group performed comprehensive central and lateral neck dissections on the side of neck nodal recurrence. Reported rates of complications were as follows: 4.5% (1/22) permanent vocal cord paralysis (notably 2 additional patients had preoperative vocal cord paralysis attributable to previous surgery or cancer involvement); rates of hypoparathyroidism were 9% (2/22) permanent and 13.6% (3/22) temporary. Not surprisingly, permanent hypoparathyroidism occurred only in patients who underwent bilateral central neck dissection because of bilateral recurrence.

Two recent studies routinely used recurrent laryngeal nerve (RLN) monitoring intraoperatively during central neck reoperation for recurrent WDTC. Farrag and colleagues reviewed their experience in a population of 33 patients who had recurrent or persistent papillary thyroid cancer (PTC), using endotracheal tubes with imbedded neuromonitoring electrodes for RLN monitoring. Patients underwent reoperative surgery on the basis of a combination of preoperative evaluations to identify additional disease, including serum thyroglobulin measurement, ultrasonography (US), and ultrasound-guided fine needle aspiration biopsy. Surgery was targeted to areas of confirmed or suspected disease on the basis of preoperative US, such that individual patients underwent either unilateral or bilateral central neck reoperation; unilateral or bilateral lateral neck dissections were performed as indicated, again on the basis of the preoperative US. Vocal fold motion was evaluated by fiberoptic laryngoscopy pre- and postoperatively in all patients.

A total of 53 central necks were operated in the 33 patients. Reported complications included 6.1% (2/33) transient hypocalcemia and no permanent hypocalcemia. Regarding the RLN, the authors reported identifying all 53 RLNs within the surgical fields successfully; however, three RLNs were “electively resected because of tumor involvement by a large paratracheal mass or tumor densely adherent to the RLN” . Whether the rate of RLN paralysis should be considered 0% or 9.1% (3/33) is therefore somewhat a matter of opinion.

Another group used hook wire electrodes implanted in the true vocal cords to monitor the recurrent nerve. Their study describes 20 patients who had central neck and mediastinal recurrence of thyroid cancer, included 18 patients who had PTC and 2 who had MTC. Of the 18 patients who were normocalcemic preoperatively, 3 (16.6%) developed transient hypocalcemia and 1 additional patient (5.6%) had permanent hypocalcemia. This group did not describe their protocol for pre- or postoperative assessment of vocal cord motion. They report that there were no new RLN injuries in the 14 patients who had normal preoperative laryngeal function.

Survival

Although WDTC is generally a relatively indolent malignancy, as many as 21% of patients eventually develop recurrent disease, the vast majority of these being isolated locoregional recurrences . Of those who develop an isolated locoregional recurrence, however, as few as 7% ultimately succumb to their disease . The above statements describe the accepted parameters of recurrence in WDTC and its general influence on survival. Although recurrence within the neck is common, the consequences of this for patient survival are modest.

Measuring the impact of reoperation on survival is difficult for several reasons: (1) prospective studies comparing a cohort of patients who had recurrent WDTC managed with reoperation to one managed expectantly or with other modalities (eg, radioactive iodine, external beam radiation) are not available; (2) a very small percentage of patients who have recurrent WDTC ultimately succumb to their disease, making the impact of any intervention difficult to detect without a large number of subjects and a lengthy period of follow-up; (3) the approach to reoperation for WDTC varies widely from study to study, ranging from targeted removal of detectable disease (“berry-picking”) to comprehensive clearance of the draining nodal beds; (4) in many studies, patients receive other treatment modalities in addition to surgery, confounding any analysis of the impact of surgery itself; (5) the natural history of WDTC involves long-term survival even in the face of ultimately fatal disease, again mandating a long period of follow-up to detect relevant outcomes data.

Other tools

Guided surgery using intraoperative US and gamma probes has recently been used to manage regionally recurrent WDTC. One group describes the management of 13 patients who had recurrences that did not concentrate radioiodine using intraoperative US with targeted surgery. They reported grossly complete resection in 11 of their 13 patients and believed that the intraoperative US was “required” for detecting the disease in 7 of the patients. Serum thyroglobulin levels became undetectable postoperatively in 7 patients. Complications and survival data are not discussed in their report, however.

Several groups have reported on the management of WDTC using radiopharmaceutical injection and intraoperative gamma probe detection. Several different radiopharmaceuticals ( ¹³¹ I, ¹²³ I, and ^99m Tc-Sestamibi) and dosing schemes have been described, suggesting the possibility of managing both iodine-avid and non-avid disease with this technique. In each report, the authors emphasize that the gamma probe allowed the intraoperative identification and removal of tumor foci that were not detected on an immediate preoperative nuclear medicine scan. Complication rates were either very low or not mentioned , and follow-up time was short.

At least one group has described the use of nonsurgical ablative strategies, such as radiofrequency ablation (RFA) and percutaneous ethanol injection (EtOH), for the management of regional and distant metastatic recurrences of WDTC. Recurrences suspected radiographically are confirmed with fine needle aspiration. Treatments are then delivered to patients under local anesthesia with sedation, with US and CT scan guidance used to deliver the treatment to the target lesion. These techniques were not without complications—in one study 22 patients underwent either RFA or EtOH procedures for recurrent neck disease, with 1 of 22 (4.5%) patients developing a permanent vocal cord paralysis and 1 of 22 (4.5%) developing a temporary one. Another patient developed a minor skin burn, which resolved with local therapy. Follow-up data in the same study showed good short-term control of the target lesions.

Certainly guided surgery (and ablation) seems likely to have some role in managing recurrent thyroid cancer. Its proper use however, remains to be determined.

The question remains: is berry-picking, even this enhanced berry-picking, appropriate? And if a more comprehensive approach is favored, how comprehensive is enough—are bilateral central and lateral neck dissections needed for all patients? The authors of the largest radio-guided series comment on these issues; their use of the gamma probe is as an adjunct, to identify foci of occult disease in the setting of a more comprehensive cleanout of the suspected involved surgical beds based on preoperative evaluation (not all beds bilaterally in most cases). They note that in 14 of their 54 patients, tumor deposits were identified in the pathology specimen that were detected neither with preoperative imaging nor with the gamma probe, and thus they argue against overly targeted surgery.