Meta-analysis of subxiphoid approach versus lateral approach for thoracoscopic Thymectomy

Thymectomy is one of the most important treatments for patients with myasthenia gravis (MG) or thymoma. In recent years, the development of surgical techniques has led to the rapid development of surgical approaches to thymectomy. Now, VATS thymectomy through the intercostal approach has been the commonly used minimally invasive surgical procedure for thymus surgery and is applied worldwide [1‐4]. SVATS is a newer alternative to LVATS and current research suggests that subxiphoid thoracoscopic thymectomy leads to less invasive than the lateral approach [5‐9]. However, many surgeons remain reluctant to adopt SVATS surgical techniques for the treatment of patients with myasthenia gravis and thymomas for several reasons. The choice of SVATS or LVATS thymectomy remains controversial. There were no systematic reviews and meta-analysis to compare SVATS thymectomy with LVATS thymectomy. The purpose of this study was to determine whether SVATS thymectomy is a better approach to the operative and perioperative outcomes. We systematically identified and evaluated the existing data comparing the clinical outcomes of SVTAS thymectomy to LVATS thymectomy by using the techniques of meta-analysis.

We identified 7 references through the aforementioned search criteria [8‐15]. A total of 7 studies, with publication dates ranging from 2004 to 2019, contained pertinent perioperative outcome information regarding VATS thymectomy for myasthenia gravis and thymomas. The screening process for the studies is shown in Fig. 1, and the characteristics of the included studies are summarized in Table 1. All the included articles were nonrandomized and retrospective. The total number of patients was 670; of these patients, 312 were treated with SVATS thymectomy, and 358 received LVATS thymectomy.

Demographics were calculated using the subset of 7 comparative studies, and the characteristics of the included studies are summarized in Tables 2, 3, 4 and 5. Quality assessment of all studies was performed by using the NOS method (Table 6).

We found mean operative time to be significantly less in patients in the SVATS group than in patients in the LVATS group (119.2 versus 138.8 min, standard difference = − 0.532, 95% confidence interval (CI): − 0.735 to − 0.329, p <0.001), as shown in Fig. 2. There was a significant difference between patients in the SVATS group and patients in the LVATS group about blood loss (46.8 versus 60.3 ml, standard difference = − 0.796, 95% CI: − 1.586 to − 0.007, p = 0.048), as shown in Fig. 3. Length of hospital stay was shorter for patients in the SVATS group (3.7 days for the SVSTS group versus 6.2 days for the LVATS group, standard difference = − 0.906, 95% CI: − 1.412 to − 0.400, p < 0.001), as shown in Fig. 4. There was no significant difference between postoperative pleural drainage stay (1.5 days for the SVATS group versus 2.6 days for the VATS group, standard difference = − 1.143, 95% CI: − 2.394 to 0.107, p = 0.073), as shown in Fig. 5. There was a significant difference in terms of postoperative complications (11 in the SVATS group versus 24 in the LVATS group, OR = 0.299, 95% CI: 0.137–0.653, p = 0.002), as shown in Fig. 6. There was no significant difference between conversion to open (4 for the SVATS group versus 6 for the VATS group, OR = 0.482, 95% CI, 0.156 to 2.166, p = 0.420), as shown in Fig. 7. There was no significant difference between oncologic outcomes (32 for the SVATS group versus 67 for the VATS group, OR = 0.582, 95% CI, 0.142 to 1.635, p = 0.241), as shown in Fig. 8.

In this study, we observed that the statistically significant clinical outcomes were decreased operative time, blood loss, postoperative complications, and shorter hospital stay, both of which favored the SVATS group. We found no differences in postoperative pleural drainage stay and conversion to open between the two groups. Most studies showed that SVATS have less pain after surgery than LVATS [8, 9, 13, 15]. Our results indicate that SVATS may be a better choice for thymectomy.

In LVATS thymectomy, surgeons may encounter a poor view of mediastinal fat and phrenic nerve at the contralateral side, and it is almost impossible to obtain adequate removal of the mediastinal fat on the contralateral side [16, 17]. Comparing to LVATS, SVATS can provide better surgical views in the upper pole of thymus and bilateral phrenic nerves [11, 18, 19], which might reduce the incidental injury, and this is essential for adequate bilateral mediastinal fatty tissue dissection. Although the bilateral approach provided adequate exposure of the anterior mediastinum, a higher number of incisions is needed, which may increase operative trauma [17]. Our findings on shorter hospital stay and less blood loss agree with those reported by Suda et al., who encourage surgeons to try this approach as one method of performing VATS thymectomy [13]. This study only included patients with thymoma, Masaoka phase I and II, so both methods can achieve R0 resection [9, 10, 12, 13].

However, all studies about subxiphoid VATS are small-scale and retrospective, further large-scale prospective study is necessary to confirm the benefit of SVATS. Our meta-analysis was limited by the inclusion of only nonrandomized, retrospective studies. Besides, there is a paucity of long-term follow-up data for patients who have undergone thymectomy for myasthenia gravis and thymomas. Our analysis was constrained by the inability to perform propensity matching because of small aggregate sample size and difficulty in obtaining individual patient information from the included studies. These factors led to increased heterogeneity within the analysis. In the end, we need to consider another factor that whether to have a total thymectomy or a subtotal thymectomy or a partial thymectomy. We mostly advocate total thymectomy in all cases of myasthenia gravis and thymomas.

Based on the findings of this meta-analysis, we conclude that for selected patients, SVATS thymectomy is safe and may achieve better perioperative outcomes to those of LVATS thymectomy operations.