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Eur J Cardiothorac Surg 2007;31:759-764. doi:10.1016/j.ejcts.2007.01.061
Copyright © 2007, European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved
Department of Thoracic Surgery, Glenfield Hospital, Leicester, United Kingdom
Received 12 September 2006; received in revised form 31 December 2006; accepted 15 January 2007.
* Corresponding author. Address: Department of Thoracic Surgery, University Hospitals Leicester NHS Trust, Glenfield Hospital, Groby Road, Leicester LE3 9QP, United Kingdom. Tel.: +44 116 256 3959; fax: +44 116 236 7768. (Email: david.waller{at}uhl-tr.nhs.uk).
| Abstract |
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Key Words: Malignant mesothelioma Extrapleural pneumonectomy Sternotomy
| 1. Introduction |
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| 2. Patients and methods |
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2.2 Operative technique
Right and left EPP via thoracotomy were performed according to the usual techniques [1,2]. For patients undergoing median sternotomy, the incision is performed in a standard fashion. The right extrapleural plane is developed from the sternal border, separating the parietal pleura from the endothoracic fascia. Blunt dissection is continued, dividing apical attachments with electrocautery. The internal thoracic vessels may be divided at their cranial origin and excised en-bloc with the main specimen together with internal thoracic lymph nodes. Insertion of an oesophageal Pillings Maloney bougie aids in the dissection of the oesophagus. The extrapleural dissection continues inferiorly until the diaphragm is reached. The pericardium is opened followed by stapled division of right pulmonary artery and right pulmonary veins intrapericardially. The lymph nodes in the subcarinal fossa are dissected and excised and the right main bronchus divided at its origin after stapling. The incision in the pericardium is extended to excise all pericardium in contact with right parietal pleura. Finally, the diaphragm is excised en-bloc, preserving a peripheral rim of muscle for future attachment of the diaphragmatic patch. The specimen is removed en-bloc from the hemithorax through the sternotomy. Systematic lymph node dissection is performed, targeting the paratracheal, paraoesophageal and peridiaphragmatic stations; the subcarinal fossa, intercostal and internal mammary artery nodes having been dissected earlier in the procedure.
In the setting of a right EPP via median sternotomy, the pericardium is reconstructed early in the operation, occasionally before excision of the diaphragm, to minimize cardiac manipulation and haemodynamic compromise. The pericardium is replaced with a loose non-absorbable mesh patch anchored to the pericardial edges with interrupted non-absorbable monofilament sutures. Excess tension in the patch is avoided, which could compromise venous drainage into the right atrium.
We replace the diaphragm with a Gore-Tex Dual Mesh patch (W.L. Gore & Associates Inc.). This is sutured to the preserved edge of the diaphragm with continuous non-absorbable monofilament suture. A sponge retractor placed through the future intercostal drain site in the anterior axillary line facilitates retraction of the liver and placement of the sutures posteriorly (Fig. 1 ). Interrupted sutures are placed posteriorly and laterally, completing with semi-continuous sutures. An intercostal muscle flap is raised via the sternotomy and secured to the bronchial stump with interrupted absorbable sutures.
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2.4 Statistical methods
Clinicopathological [7], surgical, oncological and follow-up data were entered prospectively into a database. Statistical analysis was performed using the SPSS software system (SPSS for Windows Version 11.0, SPSS Inc., Chicago, USA). Differences between groups were analysed with the Chi squared, Fisher's exact test and Student's t-test, where appropriate. Survival curves were estimated using the KaplanMeier method and the log-rank test was used to assess the statistical significance of differences between groups. A Cox proportional hazards regression model was used to identify statistically significant differences in survival and estimate hazard ratios and 95% confidence intervals (CI) [8]. The assumption of proportional hazards was assessed graphically by plotting log[log(survivor)] against log(time) for each of the prognostic groups. Prognostic variables identified by univariate analysis were analysed in a multivariate Cox model. A forward, stepwise selection procedure was used, with variables being added to the model according to a partial likelihood ratio test, using an entry criterion of p
< 0.05. Survival analyses were performed on an intention to treat basis, with the five patients who required a thoracotomy in addition to the sternotomy included in the sternotomy alone group.
| 3. Results |
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Neoadjuvant cisplatin-based chemotherapy was administered in more patients undergoing left thoracotomy (p = 0.06) and sternotomy (p = 0.007) than right thoracotomy. There were no significant differences in the proportions of patients receiving adjuvant chemotherapy (within 3 months of surgery) between the three groups.
With the exception of EORTC prognostic score [9], there were no differences between groups in terms of the following clinicopathological prognostic factors: performance status, CALGB prognostic group [10], chest pain, weight loss, haematological indices, gender or histological cell type (data not shown). There were more patients with a high-risk EORTC score in the sternotomy group (p = 0.03).
3.2 Operative results
Of the 33 in sternotomy group, 28 were accomplished by sternotomy alone. Four of the cases requiring a thoracotomy in addition to sternotomy occurred in the first 14 of this cohort, suggesting a possible reduction in likelihood of the double incision with experience (p
= 0.06). The operation time was quicker in group sternotomy and left thoracotomy than in right thoracotomy (p
= 0.008 and p
= 0.025). There was no difference in the rate of microscopic complete resection between the groups (p
= 0.8). Complete local excision (R0) was reported in 60%. The majority of patients were UICC Stage III: there was no difference in any of the stage criteria between the three groups. Thirty day or in-hospital death occurred in one (2%), three (13.6%) and three (9.1%) in the left thoracotomy, right thoracotomy and sternotomy groups respectively.
3.3 Postoperative course
Epidural usage was compared between the two right EPP groups. The total epidural volume for the first 72 h after surgery was significantly lower in the sternotomy group (p
= 0.001). There was no difference in the maximum pain score or the duration of epidural usage. We have published previously the post-operative complications in a smaller series of these patients [11]. In this study, a greater proportion of patients in the right thoracotomy group suffered complications than in the sternotomy group (17 patients in each, p
= 0.05). There was no difference in cardiovascular, respiratory or infectious complications between the groups. Compared with EPP performed by sternotomy, four patients suffered wound complications in the right thoracotomy group. No patients in the sternotomy group developed wound complications (p
= 0.02). Furthermore, we have not noted recurrence of tumour seedlings in the sternotomy wound, although one patient in this group developed recurrence at the site of a previous drain site in the anterior axillary line. Postoperative hospital and ICU stay were similar in the three groups (Tables 13
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| 4. Discussion |
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Following on from our initial report [18], we describe here our evolving experience performing routinely right EPP via a median sternotomy. In the current series of 33 patients undergoing EPP by sternotomy, we noted shorter operating times and less analgesic requirement postoperatively. We have previously reported that long operation time is an important risk factor for postoperative complications [11]. We employ routinely thoracic epidural analgesia for EPP and therefore, although the amount of epidural usage was lower in the sternotomy group, we may not have seen a substantial difference in postoperative morbidity due to the good control of pain gained with either surgical approach. However, the overall incidence of complications was lower in the sternotomy group. There are potential longer-term pain control benefits which deserve investigation, such as the potential avoidance of intercostals neuralgia. The incidence of chronic postoperative pain amongst patients following EPP is not clearly documented. It is interesting to hypothesise that sternotomy would avoid post-thoracotomy pain, but the possible contribution of parietal pleural stripping to intercostals neuralgia might remain and there is an incidence of chronic post-sternotomy pain [19].
Wound complications are relatively rare following median sternotomy and we did not experience any wound complications in this series. Neither have we yet seen tumour implantation in the sternotomy wound, although this phenomenon is well described after other incisions and needle tracks for mesothelioma. We hypothesise that this is due to the median sternotomy skin incision is distant to the pleural reflection. We are not aware of any patients suffering from sternal bone metastases.
We did not observe a difference in hospital stay between the right sternotomy and thoracotomy groups. This may be due to the policy that we have adopted, midway through the series, to transfer patients back to the referring hospital, rather than to allow discharge directly home. Patients may therefore be staying longer in our unit later.
There appears to have been a learning curve in patient selection for this technique. The first patient undergoing sternotomy had tumour related to the superior vena cava and we felt that it would be easier to gain access by sternotomy. We found that we were able to complete the EPP via sternotomy alone. An additional thoracotomy has been required five times and this is becoming less frequent with greater experience. The technical developments contributing to this include the use of the intercostal drain hole to place a liver retractor during dissection around the inferior vena cava and secondly rib resection (where required) via the sternotomy, rather than a separate thoracotomy. The retractor placed through the lateral drain hole also assists in placing the interrupted sutures for the diaphragmatic patch.
The survival data suggest that patients undergoing right EPP via a thoracotomy do not experience the same longevity as those who had a sternotomy. This effect may be related to the quicker and less morbid postoperative recovery experienced following sternotomy leading to a shorter period of relative immunosuppression. However, this cohort of our first 105 patients represents the evolution of a number of aspects of our practice which may also affect survival. These include the introduction of adjuvant and neoadjuvant chemotherapy, neither of which have yet to be adopted routinely by all our 28 referring oncological centres, but which is now a consistent predictor of good prognosis in multivariate analysis. Our preoperative assessment initially included routine contrast-enhanced magnetic resonance imaging, the use of which has waned with the introduction of multislice spiral CT. All patients now have preoperative pathological staging of the mediastinum by video-assisted cervical mediastinoscopy, regardless of whether the targeted nodes are less than 1 cm in short axis diameter. These changes in methodology account for limitations in the conclusions we may draw from survival data in univariate and multivariate analyses. Furthermore, the two right EPP groups are sequential cohorts of patients. A prospective randomised controlled trial would be required to examine the potential survival benefits of performing right EPP via a median sternotomy.
In conclusion, right EPP via median sternotomy is a feasible alternative to the standard one or two-level posterolateral thoracotomy. It is quicker, requires less post-operative epidural anaesthesia and is associated with fewer postoperative complications. The oncological result is unchanged in terms of the completeness of resection and adequacy of nodal staging and there may be a survival benefit over thoracotomy.
| Appendix A |
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Dr M. Dusmet (London, United Kingdom): I do have one question, one issue I would like you to address. I am struck in the abstract by the way the survival between right thoracotomy and left thoracotomy is so completely different, with a median survival of 259 and 658 days, respectively. Now, obviously the right thoracotomy patients were earlier in your experience because we know that over the last 5, 6 years you have converted to the sternotomy, but, to my mind, until you have explained in a satisfactory manner the 259-day median survival for right thoracotomy as opposed to more than double for left thoracotomy, I have a hard time accepting that sternotomy per se improves survival because this seems to be an anomalous number. I would appreciate your comments on that.
Dr Edwards: I accept that this is not a prospective randomized study. What I would draw your attention to is the multivariate analysis that I showed towards the end of the presentation. This showed that the right sternotomy approach was an independent poor prognostic factor in addition to chemotherapy. The use of chemotherapy in our series has increased throughout the course of time, but, as I say, there is a difference that is independent of chemotherapy with the right sternotomy group. It is difficult to know exactly why without a prospective study, and, of course, that is something that perhaps should be done in the future.
Dr Dusmet: Im still not convinced, because multivariate analysis is done on the basis of the raw data, and the raw data still has what appears to me to be an unexplained anomaly. So until you explain that apparent anomaly in a satisfactory manner, I cannot accept the conclusions of your multivariate analysis.
Dr Edwards: I take your point, and it would take a prospective randomized trial with equal oncological treatments in both groups to show that the survival benefit is due to the surgical approach. However, as you can see on the screen, there are other benefits to the approach in terms of the fact that it's quicker, it's less painful, it's less morbid, and it has fewer complications. I think those are just as important as the survival benefit.
Dr M. Zielinski (Zakopane, Poland): Maybe I am too pessimistic about the results of treatment of mesothelioma, but in my opinion, in my experience, it is a totally incurable disease now, and everything we can do is to prolong the life to some extent, nothing more. The main cause of death in the experience of my team is the recurrence in the abdomen.
I would like to ask you a question. You showed the results that the sternotomy approach prolonged the survival. What were the causes of death in your material? I think regardless if you perform sternotomy or thoracotomy, the patient dies from the intra-abdominal recurrence. The approach has no role in that. So what were the causes of death in your patients?
Dr Edwards: I will refer you to the paper that we have published showing our patterns of recurrence following extrapleural pneumonectomy in our series, but we have seen recurrence both locally and distally and in the abdomen, and I think it's about one-third of patients have recurrence in the abdomen at the time of death. But, as I say, what is important, what is interesting with this series is that we didnt see any wound recurrence in the sternotomy wound, which I think is interesting.
Dr Zielinski: In other words, how can you explain in what way sternotomy prolongs survival? That's the point.
Dr Edwards: What Im saying is that there is an association with increased survival. Im not suggesting that this is a causal relationship.
Dr Waller: I would just like to address the chairman's apparent misunderstanding of why he cannot understand the difference between left and right. Let me draw you to two pieces of well-published evidence. One is the higher mortality associated with right pneumonectomy compared to left pneumonectomy for non-small cell lung cancer for well-known reasons, such as cardiovascular mortality, which would largely explain some of the differences in the mortality between left EPP and right EPP, and also the presentation we made at this society, I think it was in 2005, which has been published in the European Journal of Cardiothoracic Surgery which highlighted the prognostic indicators for survival in our series, which included length of operation, and I will put it to you that the reason there is a difference between right thoracotomy and median sternotomy is the reduction in the operating time, which we know is associated with postoperative complications. The difference between the left and the right relates to the anatomy and removing a right lung compared to a left lung.
Dr Dusmet: If the differences were exclusively the difference between right and left thoracotomy, I would have expected to see a degree of that remaining after sternotomy.
Dr F. Leo (Milan, Italy): Again, regarding survival and median sternotomy, dont you think that there is a major bias in selection of patients mainly due to the extent of the disease?
Dr Edwards: As I showed, the T stage and the N stage and the overall stage were the same between the groups. These are sequential cohorts and we have not changed our selection criteria throughout the course of the series.
Dr Leo: Sure, but if you have bulky disease on the diaphragm, Im not sure that you can be radical with median sternotomy.
Dr Edwards: It makes the operation difficult, but it is still feasible.
Dr D. Branscheid (Grosshansdorf, Germany): First, what type of histology did you find? Did you treat sarcomatous, epithelial, or biphasic ones? Second, what was the stage? How extended were those tumors?
Dr Edwards: Firstly, histology, we did not include patients who had definite nonepithelioid tumors in this group; however, some patients following radical surgery were found to have biphasic rather than pure epithelioid tumors. Secondly, the vast majority of our patients, as in other international series, are stage III patients.
| Footnotes |
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| References |
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