Abstract
To study the safety of prophylactic level VII nodal dissection regarding hypoparathyroidism (temporary and permanent) and vocal cord dysfunction (temporary and permanent) and its impact on disease free survival. This prospective study concerned 63 patients with papillary thyroid carcinoma with N0 neck node involvement (clinically and radiologically) in the period from December 2009 to May 2013. All patients underwent total thyroidectomy and prophylactic central neck dissection including levels VI and VII lymph nodes in group A (31 patients) and level VI only in group B (32 patients). The thyroid gland, level VI and level VII lymph nodes were each examined histopathologically separately for tumor size, multicentricity, bilaterality, extrathyroidal extension, number of dissected LNs and metastatic LNs. Follow-up of both groups, regarding hypoparathyroidism, vocal cord dysfunction and DFS, ranged from 6-61 months. The mean age was 34.8 and 34.3, female predominance in both groups with F: M 24:7 and 27:5 in groups A and B, respectively. Mean tumor size was 12.6 and 14.7mm. No statistical differences were found between both groups regarding age, sex, bilaterality, multicentricity or extrathyroidal extension. The mean no. of dissected level VI LNs was 5.06 and 4.72 and mean no. of metastatic level VI was 1 and 0.84 in groups A and B, respectively. The mean no. of dissected level VII LNs was 2.16 and mean no. of metastatic LNs was 0.48. Postoperatively temporary hypoparathyroidism was detected in 10 and 7 patients and permanent hypoparathyroidism in 2 and 3 patients; temporary vocal cord dysfunction was detected in 4 patients and one patient, and permanent vocal cord dysfunction in one and 2 patients in groups A and B, respectively. No significant statistical differences were noted between the 2 groups regarding hypoparathyroidism (P=0.535) or vocal cord dysfunction (P=0.956). The number of dissected LNs at level VI only significantly affected the occurrence of hypoparathyroidism (<0.001) and vocal cord dysfunction (<0.001).The DFS was significantly affected by bilaterality, multicentricity and extrathyroidal extension. Level VII nodal dissection is a safe procedure complementary to level VI nodal dissection with prophylactic central neck dissection for papillary thyroid carcinoma.
Highlights
The number of dissected lymph nodes (LNs) at level VI only significantly affected the occurrence of hypoparathyroidism (
Since level VI, which sits high up in the neck, as well as level VII, which is hidden behind the manubrium sterni and medial thirds of both clavicles, cannot be assessed accurately by ultrasound and CT with poor sensitivity ranging between 50 and 70 % Mulla (2012), in addition, normal-sized, Level VII lymph nodes can still harbor macrometastatic disease (Wang et al, 2013), and since level VII nodes are an important and integral prognostic factor in papillary thyroid carcinoma (Choi et al, 2011; Wang et al, 2013; Fayek 2015); the dissection of those nodal groups is an important step in the management plan of Papillary thyroid cancer (PTC)
Putting in mind that prophylactic central nodal dissection (pCND) was advised by the European Thyroid Association, the British Thyroid Association, and the American Thyroid Association (Pacini et al, 2006; Grubbs et al, 2007) and its benefit in the accurate staging of the tumor, which may guide subsequent treatment and follow-up, in addition to decreasing the recurrence of PTC, improving disease-specific survival, and significantly reducing levels of serum thyroglobulin, increasing the rate of athyroglobulinemia (White et al, 2007) so pCND was done in all patients of this study
Summary
Given the high rate of subclinical nodal metastases in PTC, many centers, have moved to routine prophylactic central nodal dissection (pCND) at the time of total thyroidectomy (TT) for all patients with PTC, pCND allows for more accurate assessment of nodal status, decreases the rate of local recurrence, reduces morbidity from reoperation if required, and may guide the dose of ablative postoperative radioiodine given (Mazzaferri EL Jhiang 1994; Scheumann et al, 1994; Hughes et al, 1996). Dralle (2012) reports a significant risk of postoperative hypoparathyroidism after CND but suggests that pCND improves prognosis for papillary thyroid cancer Dralle (2013). Many studies showed an increased risk of recurrent paralysis in patients undergoing CND, with rates of recurrent lesions ranging between 1% and 12% (Moo et al, 2009; Choi et al, 2010; Hughes and Doherty 2011). Tartaglia et al, 2014 reported no significant difference between TT alone or TT with CND. The American Thyroid Association’s consensus statement on terminology of CND defines the innominate artery as the lower limit of a CND and this equates CND to level VI and the superior portion of level VII (ATA consensus, 2009)
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