Abstract
Summary
Objectives
There is a resurgence of interest in lung-sparing extirpative surgery for malignant pleural mesothelioma with recent reports of better survival and fewer adverse consequences than with extrapleural pneumonectomy. However, these operations are not well-characterized and to offer evidence-based clinical recommendations and to plan future trials a summary of what is already known is required.
Design
A formal literature search was performed and all recovered titles were sequentially sifted by title, abstract and full-text reading according to prespecified criteria. Papers were selected if they contained data relevant to the area of enquiry. Quantitative synthesis and textual analysis, appropriate to the material, were performed.
Setting
Follow-up studies of patients undergoing surgery for malignant pleural mesothelioma in specialist thoracic or cardiothoracic units.
Participants
Among the operated patients described in these papers, a total of 1270 patients had undergone lung-sparing surgery for mesothelioma.
Results
There were no randomized trials or other forms of controlled studies. From 464 titles, 26 papers contained sufficient data on 1270 patients to be included in the systematic review. Operative descriptions for all series were extracted and tabulated and variation was found in the nature of surgery within and between series, and the degree of detail with which it was described. There was more operative detail in recent papers. All available numerical data were extracted, tabulated and summarized using quantitative methods. The average survival at 1, 2, 3, 4 and 5 years was 51%, 26%, 16%, 11% and 9%, respectively. There were no data on patients’ performance status, symptomatic change, or other patient reported outcomes.
Conclusions
In the absence of any form of control data, no conclusions can be drawn concerning survival differences or symptomatic benefits attributable to surgery. As mesothelioma surgery is restricted to a selected minority of patients who often have multiple therapies, future research will require controlled studies with explicit definitions of the clinical and surgical intent.
Introduction
The incidence of malignant pleural mesothelioma (MPM) in Europe is still rising and
Britain has the highest mesothelioma death rate in the world. Flow diagram to show the stepwise process of sifting and selecting papers
No part of this practice was subjected to randomized trial prior to the Mesothelioma and Radical Surgery (MARS) trial. Extrapleural pneumonectomy (EPP) accompanied by adjuvant therapy was regarded as offering the best prospect of prolonged survival following Sugarbaker's report about 10 years ago 4 but a large multivariate analysis comparing the results of EPP with pleurectomy/decorticiaton (PD) has since shown better survival for the lung sparing form of surgery. 5 It was stressed by the authors that this difference in favour of PD was despite the observation that the group undergoing PD were considered to have a relatively worse prognosis and to be less favourable cases for surgery. 5 At the same time there has been an increased interest in PD 6, 7, 8 and it is given prominence in recent European guidelines. 9
In the literature a range of terms appear but pleurectomy/decortication appears in both European 9 and American guidance. 10 Pleurectomy may be termed partial, total or radical while the relative incompleteness of the extirpation of the cancer is signified by terms such as debulking, occasionally cytoreduction, and increasingly by the term macroscopic complete resection. What these operations have in common is that they are all extirpative surgery for mesothelioma, which does not include pneumonectomy. It is this surgery that is the subject of this systematic review.
Materials and methods
The literature was searched using a formal strategy (Appendix 1 – see Patient age over time. For publications where the age in years (vertical axis)
of operated patients is provided (mean age for 16 studies and the range in 23).
The data are plotted against the year of publication
Papers were individually searched and data extracted (ET) and all data included in analyses were confirmed in working sessions with two or more of the authors working together (ET, FF, TT). We looked for the start and end dates of the reported series, the number of patients reported, sex, age, tumour histology, stage, asbestos exposure, laterality, type of surgery performed, any adjuvant therapy, all survival data available, respiratory outcomes, and patterns of recurrence. We performed a textual analysis of the descriptions of operations performed. We constructed evidence tables and created graphical displays of aggregated and discrete data as appropriate.
Results
The search resulted in 464 titles which by various inclusion/exclusion processes resulted in 26 papers containing data on lung-sparing surgery (Figure 1). 5, 7, 8, 11, 12, 13 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33 There were no randomized trials or studies comparing the outcomes of surgery with a non-operated control group. The reports were heterogeneous, some reporting various forms of surgery within the same report and others reporting surgical patients within an overall experience including non-operated patients. This made analysis difficult so we have been careful not to over interpret any findings but to present them with the stated limitations.
A total of 1270 patients are included in the reports used in the analysis although the number incorporated varies from one data summary to another because data were not available for every analysis in all papers. The (weighted) mean age in the whole series was 62 years. The average age shows a small upward trend over the 30 years of reported data but the age range of patients included is essentially unchanging over 25 years of reporting (Figure 2). Male patients are in the majority in all reports with an average of 80% men.
Asbestos exposure was recorded in 13 papers 7, 8, 13, 16, 17, 22, 24, 25, 27, 31, 32, 33 and was positive in 64% of patients (682/1061 patients) with a range of 17–95%. The rate in some reports is given for all mesothelioma patients, not just those operated. The variation in the asbestos exposure rate is more likely to be attributable to the assiduity of recording rather than a real epidemiological variation.
In four reports 5, 11, 12, 13 including 564 patients (individual series included 15, 26, 245 and 278 patients) 60% had right-sided disease with the proportion ranging from 52–62% for the four series included. This is consistent and the difference between right and left may simply reflect the relative surface area of pleura at risk.
In 14 reports
8,
12,
13,
17,
22,
24,
26
the breakdown of operated patients by histology is provided ( For the 14 papers in which the histology of operated patients was found the
absolute number of cases of each classification is illustrated, ranked by total
cases to aid the eye
Staging and median survival in months as given in seven reports
A textual analysis of the operative descriptions for lung sparing extirpative surgery in its various forms. Where a study included more than one form of surgery (as determined by the authors, for example the Mayo Clinic report of Schipper et al.) these are described separately. The studies are in date order of reporting
Where a report includes a mixture of operations and/or operated and non-operated patients the number of patients having lung sparing extirpative surgery is given as the numerator and the total number of patients in the report as the denominator
Some of these operations included planned multimodality therapies but for the purposes of this table we confine ourselves to the technical details of the extirpative surgery
The authors state ‘Decortication and pleurectomy, when possible, is the treatment of choice’ so the total versus partial presumably applies to either or both components of the surgery
The brevity of this operative detail is in marked contrast to the very full description of EPP performed in the other 40 patients in the same series
Resection of pericardium and diaphragm was sometimes not removed, or partially removed, in an unstated number of patients. ‘Partial or no removal of pericardium or diaphragm was sometimes done for a parietal pleural tumor separable from the pericardium or diaphragm.’
There is a consistent theme of modifying the operation according to the intra-operative findings. In earlier papers this tended towards conservativism, non-radical, sparing the diaphragm, sparing the mediastinal pleura and with a textual reminder that the surgery has a palliative intent. For example ‘A lesser procedure such as decortication/pleurectomy was considered for locally extensive disease but only for relief of pain or shortness of breath’. ‘The aim of this procedure was to attempt palliation of troublesome symptoms particularly chest pain and pleural effusion.’ 21 In some, particularly more recent series, PD is performed with radical intent. 8
We judge that resection of the diaphragm or pericardium was infrequently performed in early series because it is specifically mentioned if done 16, 31, 32 whereas it is included in the general operative description in more recent reports. 5, 8, 11, 13 It appears that it was optional with a degree of selection for appropriateness but it is often unclear in how many patients these steps were taken (Table 2).
All survival data that could be extracted from the reports. Where data are stated in the paper, in text or tables, these have been used. Where the data were displayed graphically the proportion alive at 1, 2, 3, 4 and 5 years has been read from the graphs to supplement the data reported in text and tables

Survival at 1–5 years from 23 papers providing data either in the text or graphs. The circle size is proportional to the number of patients reported in the series as in the key
Adjuvant therapies were used (probably) in all later series but it was very variable, and when reported, the stage of disease and the interventions used were not well enough characterized to attempt analysis. There were no data on performance status, quality of life, symptomatic change, or other patient reported outcomes.
Discussion
The evidence tables and figures provide an historical record of the outcomes of 50 years
of lung-sparing surgery for MPM. There are no randomized studies and no direct or
indirect comparison with the survival of comparable unoperated patients. The limitations
on the inferences that can be drawn from retrospective case series have been previously
enumerated.
34
It is of course negotiable which papers to include and which to exclude. These
decisions were made in the interests of finding data rather than to fit any prior belief
and we hope that we have not overlooked any publication that would cast new or further
light on the research question – which is the effect of lung sparing extirpative surgery
for malignant pleural mesothelioma. For 22 reports where the median survival (months) and the start and end dates
of the clinical series are provided, they have been plotted graphically against
the mid-point of the series. The size of circles is proportional to the number
of patients reported in the series (see key)
As a result of applying the test that the included publications should provide data that enabled some level of analysis, exclusion of some important papers concerning PD were made. An example is the report by Grossebner et al. 35 It describes a videothoracoscopic approach with the emphasis on diagnosis, pleural fluid control and lung mobilization, all with palliative intent. This is the subject of an ongoing randomized controlled trial. 36 Also excluded was a study where patients having ‘maximum debulking surgery’ either EPP or PD and complex adjuvant therapy were randomized, half having photodynamic therapy. 37 As the purpose of that study was evaluation of photodynamic therapy and the surgery was mixed it was excluded from our analysis. However, other studies with primary intent of reporting one or more adjuvant therapies were included if they also included data in lung sparing surgery which could be analysed. The judgements were made on the basis of utility of the data for the present analysis. It should be emphasized that we had no patient level data and that the analyses are illustrative rather than definitive.
Figure 4 shows the survival for first to fifth year after surgery and Figure 5 shows the median survival with the size of symbols proportional to the number of patients in the series. We have not attempted to produce an aggregated statistic because of the heterogeneous nature of surgery but the eye can see that there is a consistency in results among the larger series with smaller series tending to be outliers. The illustration shows that six larger series, with more than 50 and more than 100 cases included, had median survivals of 10–15 months. Does this represent longer survival than these patients would have had without resection? In a report of 945 patients with malignant pleural mesothelioma 38 those who had no surgery (n=387) had a mean survival of 16.8 months and those who had an exploratory thoracotomy but no resection (147/558; 31%) survived on average 17.8 months. 39 It is understood that these were patients with less favorable clinical and pathological characteristics than those selected for surgery, but they fared as well as the operated patients.
The work of those deriving better staging systems is of great importance. It is noteworthy that in a series of 262 patients undergoing a range of treatments in South Africa, performance status and Butchart staging were correlated with survival across all treatment groups. 40 Clearly standardization of a form of staging generally applicable to preoperative patients (rather than relying on intra-operative or pathological evaluation) will be essential in any future trials.
Between the 1960s and the present, the time span of the 1270 operations summarized, there will have been changes in practice and case selection, and in the use of effective chemotherapy. The variety of textual accounts in Table 1, with surgeons making intra-operative decisions on how much can be removed, illustrates the imperative to standardize the operation for any future studies if they are to have meaning and allow surgeons to compare their own with reported results, and the work of others. This is evident in the work of Waller's group in Leicester, UK. 6, 7, 8 It is also likely that any impression of longer survival in more recent series may be due to other factors such as lead time bias due to earlier detection in the modern era, stage migration with contemporary imaging, and the likely effect of reporting bias. Therefore any discernable change cannot reliably be ascribed to newer rather than earlier techniques. More sophisticated analyses with newer statistical techniques would not clarify whether there is a difference in survival attributable to any particular factor. The question remains whether any of the operations described in Table 2 make a difference to outcome.
In 1988 Alberts wrote ‘Despite enthusiastic reports of response to treatment, untreated patients with malignant pleural mesothelioma may survive just as long as treated patients’. 40 The authors cited the Brompton group's analysis of surgical results in support of this contention. 33 Achatzy et al. observed ‘It is interesting to note that the long-term prognosis of patients treated non-operatively was better than that of surgically treated patients. In the non-operative group, the 5-year survival was 11.4% (5 of 44 patients) whereas in the operative group, the comparable figure was 2.2% (4 of 178 patients)’ and yet they concluded ‘Decortication and pleurectomy, when possible, is the treatment of choice’. 32 Since lung-sparing surgery is being promoted as a clinical option for MPM patients in the modern era, knowledge of these results should be available to inform patients. If we are to move the emphasis from making an impact on survival to improving the quality of that survival, then more information is required concerning patient reported outcomes, their ability to breathe, and their quality of life.
Footnotes
DECLARATIONS
Footnotes
Acknowledgements
None
