| Objective: Currently,the treatment of benign parotid tumors is surgical dissection,but the excision scope and surgical methods remain controversial.The traditional treatment of benign parotid tumors is superficial parotidectomy(SP),which includes the dissection of the branches of the facial nerve,ligation of parotid duct,removal of the whole superficial lobe of the parotid gland together with the tumor.Superficial parotidectomy is considerd to be safe and reliable.It can minimize the recurrence of the tumors.However,while the recurrence rate improves,the number of complications increases,including facial nerve paralysis,Frey's syndrome,salivary fistula and facial malformation.Regional resection is also called partial superficial parotidectomy(PSP).As a kind of parotid benign tumor excision method,PSP takes small trauma – it only need to dissect part of the facial nerve and retaine most of parotid main duct or branch duct and some superficial parotid gland tissue.PSP can not only guarantee the complete resection of the tumor to reduce the recurrence and retain some function of the parotid gland,but also reduce facial deformity after the parotid gland surgery and the occurrence of postoperative complications.Nevertheless,the controversy between SP and PSP still exists.Methods: In this study,we use systematic literature review and Meta-analysis methods to collect relatively literature about postoperative outcomes of SP and PSP,then analysis recurrence rate and complication rate by evidence-based medicine to provide a theoretical basis for the selection of the appropriate surgical approach in clinical.1 Materials and Methods1.1 Search StrategyRelevant studies that compared the outcomes of partial superficial parotidectomy and superficial parotidectomy for the parotid benign tumors were searched in Pubmed,CNKI and Wangfangdata databases by the end of March 2016.The following words or terms were adopted:1)partial superficial Parotidectomy,Regional resection;2)parotid neoplasm,parotid tumor and parotid.These two search terms were combined using the Boolean operator ‘and'.Furthermore,we searched additional relevant studies by manual searches and reference backtracking.1.2 Documents Screening Inclusion and exclusion criteria:1)the studies could be defined as a case-control study or a cohort study;2)the objects of studies should be patients with primary,solitary,clinically benign parotid epithelial tumors.Studies involving recurrent,multiple,malignant tumors or non-salivary original tumors were excluded;3)Surgical techniques for PSP and SP were clearly described.In this study,SP is defined as removing the complete or almost complete superficial lobe with the tumor after planned identification and dissection of the facial nerve;PSP is defined as removing the tumor with part parotid tissue of superficial lobe with or without identification and dissection of the facial nerve.4)PSP was required for patients to be assigned the test group whereas SP was used to assign patients to the control group;5)Complete data were available with a specific number of cases(?5);6)At least one of the following outcomes was included(recurrence,facial weakness,Frey's syndrome,salivary fistula).If the duration and sources of study population recruitment overlapped in two or more papers by the same authors or same centers,the most recent study or the study with the larger number of participants was included.1.3 Data Extraction Two authors independently extracted the following data for each included study,and any disagreements were resolved by consulting the third author.The factors of data extraction:1)General information(first author,publication year,source,and author's country);2)Study design;3)Number of cases;4)Length of follow-up;5)Incidence of recurrence,Facial weakness,Frey's syndrome and salivary fistula;6)Conclusions.1.4 Statistical Analysis Meta-analysis was performed using software Rev Man 5.0.The Odds Ratio(OR)with 95% CI was determined for dichotomous data.The significance level was set as 0.05.Heterogeneity between studies was detected with a Chi-square test before pooling data,and the quantity of heterogeneity was measured with the I2 statistic.If the I2 value was <50%,the fixed-effects meta-analysis was applied;if the I2 value was ?50%,the random-effects meta-analysis was used.In the presence of heterogeneity,a sensitivity analyses was performed by removal of each study in turn in order to examine the stability of the main results.Potential publication bias was investigated by visual assessment using a funnel plot and further examined using a combination of the Egger regression test and the ‘trim and fill' method with Stata 11.0.Results:2.1 Search results Two hundreds and twelve potentially relevant studies were obtained after initial search and reference backtracking.Then the studies were further screened according to inclusion and exclusion criteria.Finally,20 studies were selected for the Meta-analysis,of which 12 were from China,2 were from Germany,one were from US,Norway,Israel,Netherlands,Spain,Greece,Finland,respectively.The studies were published during the period 1997 to2016.A total of 2,376 participants were included in those studies,of which1,099 underwent PSP and 1,277 underwent SP.These studies included the incidence of recurrence,Facial weakness,Frey's syndrome or salivary fistula.2.2 Recurrence rate Twelve studies reported the recurrence rate after surgery.The recurrence rates for PSP and SP were 1.14%(8 of 704 cases)and 0.62%(5 of 806 cases),respectively.As between-study heterogeneity was not observed(P = 0.98,I2 =0.0%),a fixed effects model was used for analysis.There were no statistically significant in recurrence rate between PSP and SP(P = 0.42).2.3 Facial weakness Sixteen studies reported the transient facial nerve paresis rate after surgery.The rates of transient facial nerve paresis for PSP and SP were11.82%(101 of 854)and 27.69%(239 of 1058),respectively.As between-study heterogeneity was not observed(P=0.09,I2 =33%),a fixed effects model was used for analysis.The rate of transient facial nerve paresis of PSP was significantly lower than that of SP(P <0.00001).Nine studies reported the permanent facial nerve paralysis rate after surgery.The rates of permanent facial nerve paralysis for PSP and SP were1.03%(6 of 579)and 4.31%(31 of 695),respectively.Because between-study heterogeneity was absent in the result(P = 0.11,I2 = 40%),a fixed effects model was applied in this meta-analysis.The rate of permanent facial nerve paralysis of PSP was still significantly lower than that of SP(P <0.00001).2.4 Frey's syndrome There were 17 studies that reported the incidences of Frey's syndrome.The incidences of Frey's syndrome in PSP group and SP group were 8.98%(75 of 835)and 28.9%(327 of 1128),respectively.Due to significant between-study heterogeneity was observed(P <0.0001,I2 = 60%),a random effects model was used for further analysis.It seemed that PSP could reduce the risk for Frey's syndrome significantly(P <0.00001).2.5 Salivary fistula Salivary fistula was reported by 5.71%(28 of 490)in PSP group compared to 2.96%(42 of 357)of SP patients in 9 studies.Due to significantbetween-study heterogeneity was observed(P=0.03,I2 = 54%),a random effects model was used for further analysis.There was no significant reduction in salivary fistula in the PSP group compared to the SP group(P =0.06).2.6 Publication bias As shown in funnel plot(with Frey's syndrome involved in the literatures,for example),the selected literatures generally arranged symmetrically around the center.Egger regression test showed there was no publication bias among these studies(P>0.1).Conclusions:This systematic review with meta-analysis suggests that PSP has a similar recurrence rate as SP,but PSP can significant reduce the complications of facial weakness,Frey's syndrome and salivary fistula. |
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