2017 Section 7 Green Book

PROPHYLACTIC CND DID NOT SIGNIFICANTLY LOWER LRR

imaging modality in all studies, but only two studies specif- ically mentioned that both bilateral central and lateral neck compartments were examined (25,27). In terms of selection for pCND, seven studies were based on individual surgeon’s preference (7,18,22,24,25,27,28), while four studies did not specify their method of selection (17,19,23,26). Three studies used historical controls (TT alone) for comparison (20,21,29). Only 11 of 14 studies statistically compared age, sex ratio, tumor size, extrathyroidal extension, and tumor multifocality between the two groups (7,17,18,21– 26,28,29). Of these, two studies found age to be significantly older in group B (21,25), and three studies found tumor size to be significantly different (7,21,23). Two studies found tumor size to be significantly larger in group A (7,21), while one study found tumor size to be significantly smaller in group A (23). Three of nine studies found the rate of extrathyroidal extension to be significantly higher in group A (7,22,24), and two of nine studies found the rate of tumor multifocality to be significantly higher in group A (22,26). Bilateral pCND was performed in eight studies (17,18,22–24,26,28,29), while the other six studies performed either unilateral or a combination of unilateral and bilateral pCND (7,19,20,21,25,27). Among the eight studies reporting bilateral pCND (17,18,22–24,26,28,29), the mean number of central lymph nodes harvested ranged between 5.6 and 9.6, while the one study reporting unilateral pCND harvested a median of five (7). The incidence of central LNM in group A ranged from 23.5% to 82.4%, while in group B it ranged from 0.9% to 9.7% with 9 of 14 studies not reporting the incidence of central LNM in group B. Table 2 shows a comparison of outcomes between the two groups. Only 9 of the 14 studies reported whether RAI abla- tion was given after surgery (7,18,21–24,26,27,29). Their dose ranged from 2.78 to 5.55 GBq. One study empirically gave the same dose of RAI, irrespective of the extent of LNM (7). The mean frequency of postoperative RAI ablation in groups A and B were 746/1041 (71.7%) and 498/937 (53.1%). Group A was significantly more likely to receive RAI ablation than group B (OR = 2.60 [CI = 2.12–3.18]). This was expected be- cause of the higher incidence of central LNM (or N1a) in group A leading to tumor group upstaging in patients older than 45 years (28). Only 1 of 14 studies compared operating time between the two groups and found group B to have a significantly shorter operating time than group A (28). Figure 2 shows the forest plot for temporary hypocalcemia. Of the 14 studies, 11 studies compared temporary postoper- ative hypocalcemia between the two groups, while 10 studies compared permanent postoperative hypocalcemia in the two groups. In eight studies, permanent hypocalcemia was de- fined as persistent hypocalcemia and/or need for calcium supplements for more than six months (7,20,23–28), while two studies defined it as more than 12 months (18,29). If one as- sumed all studies utilized a similar definition for temporary and permanent hypocalcemia, the overall temporary hypo- calcaemia rate in group Awas significantly higher than that in B (336/1294 (26.0%) and 144/1330 (10.8%), respectively; OR = 2.56 [CI = 2.04–3.21]) while the overall permanent hypo- calcaemia was also similar between the group A and B (25/ 1254 (2.0%) and 15/1257 (1.2%), respectively; OR = 1.74 [CI = 0.87–3.50]). Surgical outcomes

conducted using R version 2.15.1 (R Foundation for Statistical Computing, Vienna, Austria) and the metafor package (16).

Results

Figure 1 shows the flowchart of studies retrieved and ex- cluded. Of the 1822 titles initially identified from the database search, 41 full-length articles were assessed for inclusion, of which 27 were excluded and 14 studies were determined to be eligible and were included in this systematic review (7,17–29). Appendix Table A1 lists these 27 articles (6,8,30–54) and the reason for their exclusion. No additional study was found from our search of the three bibliographies in previous meta- analyses (9–11). One study (8) was excluded, as it analyzed a subset of study subjects that were later recruited in a multi- center cohort study (25). Table 1 shows a comparison of the baseline characteristics between the 14 eligible studies. There was no randomized trial. Thirteen studies were retrospective, while one was prospective. Of the 3331 patients included, 1592 (47.8%) un- derwent TT + pCND (group A), while 1739 (52.2%) under- went TT only (group B). In terms of preoperative nodal assessment, ultrasonography (US) was used as the standard Baseline characteristics

Flow diagram for study selection.

FIG. 1.

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