The search for a cure for mesothelioma is a regular battle in hospitals and research facilities all over the world. The traditional modalities of cancer treatment—surgery, chemotherapy and radiation—have not yet succeeded in stopping this terrible illness, but pioneering physicians are exploring new techniques, as well as refining traditional treatments. An important element in the process of refining standard therapies are the papers summarizing the historical efficacy of individual surgical methods. These analyses give doctors statistical information on a specific institution’s experience with these techniques, which can be helpful in determining treatment courses for future patients who may be eligible for similar surgeries. Doctors from the Mayo Clinic have recently released a paper that summarized the Clinic’s previous 18 years of surgical experience in the treatment of pleural mesothelioma.

Introduction to the Study

The authors of the paper undertook a retrospective analysis of the Mayo Clinic’s 18 previous years of mesothelioma treatment. Using the Clinic’s main database, they surveyed the results of all patients who underwent surgery for mesothelioma between January 1, 1985 and December 31, 2003.

The surgical procedures identified fell into one of five categories:

1. Extrapleural Pneumonectomy (EPP). The paper defined the extrapleural pneumonectomy as “...the en bloc resection of the involved ipsilateral parietal pleura, lung, pericardium, and diaphragm. The diaphragm and right pericardium were reconstructed with polytetrafluoroethylene soft-tissue patch.”
2. Total Pleurectomy. The paper described a total pleurectomy as consisting “...of a complete extrapleural stripping of the parietal and mediastinal pleura and involved visceral pleura from the ipsilateral hemithorax without performing pulmonary resection. Total pleurectomy also included resection of the diaphragm and pericardium when necessary.”
3. Subtotal Pleurectomy. The authors defined this procedure as “...removal of up to 70% of the parietal pleura with debulking of as much of the mesothelioma as possible. Subtotal pleurectomy was a less extensive resection than total pleurectomy.”
4. Exploration without Resection. The paper describes this procedure as consisting of “...posterolateral thoracotomy with an extensive dissection performed; however, resection of mesothelioma was not ultimately performed because of identification of unresectable disease.”
5. Biopsy Alone. In this case, the authors defined this procedure as “...performed by means of video-assisted thoracic surgery or limited thoracotomy. Biopsy alone involved very limited dissection and resulted in only a pleural biopsy.”

Results

The analysis consisted of 285 patients, of which 236 were men and 49 were women. The average patient age was 66 years old. 146 patients underwent a biopsy alone, 73 underwent an extrapleural pneumonectomy, 34 underwent a subtotal pleurectomy, 22 were given an exploration without resection and 10 patients received a total pleurectomy. Histologically, the patient breakdown was within the expected averages: 134 patients (47%) presented with epithelial mesothelioma, 39 patients (14%) presented with biphasic mesothelioma and 39 other patients presented with sarcomatous mesothelioma, while 18% were unclassified or presented with desmoplastic mesothelioma. In terms of staging, 20 patients presented as stage IA, 82 patients as stage IB, 24 patients as stage II, 75 patients as stage III, 60 patients as stage IV and in 24 patient records a staging classification was not given.

Surgical Breakdown: Extrapleural Pneumonectomy

An extrapleural pneumonectomy is a radical procedure that historically was associated with high mortality and high morbidity. However, it has always had the potential to remove a large extent of malignant tissue, so has often been the treatment of choice for many thoracic surgeons. Improvements in technique have significantly lessened the overall mortality figures, but it is still associated with major complications. In the cohort under discussion, an EPP was the most often used invasive surgical method. Median survival was 16.0 months for this group. One-year survival was listed at 61% and two-year survival at 25%. Slightly greater than 50% of this group experienced a major complication.

Surgical Breakdown: Total Pleurectomy

In most institutions, the two major surgeries performed for mesothelioma are an EPP and a total pleurectomy and there is still disagreement among surgeons regarding which procedure is the most effective. In the case of the Mayo Clinic, only 10 total pleurectomies were performed, so statistical comparisons in this data set are limited by the small sample size. That said, for those patients who received a total pleurectomy at the Mayo Clinic, median survival was 17.2 months, the one-year survival figure was listed at 80% and the two-year figure was listed at 35%, all of which were greater than the EPP group. Only 20% of this group (however, this was only 2 patients) experienced major complications, as compared to 50.7% for the EPP group. Again, though, the small sample size makes precise comparisons between procedures impossible.

Surgical Breakdown: Biopsy Alone

146 patients only underwent a biopsy. This was most commonly done for patients with very extensive disease or for patients with a very low performance status. All surgeries performed for mesothelioma are quite taxing on the body, so patients who present with the above description would only be treated in a palliative manner. The median survival was 9.2 months for this patient class. The one-year survival figure was listed at 36% and the two-year figure at 13%.

Surgical Breakdown: Exploration without Resection and Subtotal Pleurectomy

Neither of these procedures are official treatments. In all cases, the surgeon had planned for an EPP or a total pleurectomy, but interoperation discoveries prevented the full completion of either procedure so the surgeon’s work was limited by the patient’s presentation. The median survival figure for patients who underwent a subtotal pleurectomy was 8.1 months, with the one-year survival figure listed at 30% and the two-year figure at 15%. For patients who underwent an exploration without resection, the median survival time was 6.8 months, with a one-year survival figure of 45% and a two-year figure of 10%.

Conclusion

The results as presented by the Mayo Clinic are within the standard figures for most treatments of pleural mesothelioma. While individual procedures may be skew a little higher or a little lower as compared to other studies, the overall results still point to greater research being necessary before serious improvements are made for the management of mesothelioma.

Labels: mesothelioma