Disease staging is one of the fundamental steps in the development of a treatment plan for patients with mesothelioma. Effective measurement of tumor spread and the identification of distant metastases are important indications of long-term prognosis and, therefore, are determinate conditions in deciding which patients are eligible for radical surgery and which patients will be treated less invasively. Generally speaking, patients who are considered Stage I-III for pleural mesothelioma may be acceptable for “curative” surgeries such as extrapleural pneumonectomy, while patients with Stage IV disease are excluded from these procedures and will be treated palliatively. Staging is designed to separate out patients so those in the disease’s later stages do not undergo operations that are associated with significant surgical complications and extended recovery time when their long-term prognosis is not hopeful.

Historically, however, there have been difficulties in the accurate determination of stage because of mesothelioma’s unique behavior and morphological form. Unlike most other cancers which present as an individualized tumor with clear boundaries (even if there are multiple tumors, they generally fit this same individualized pattern), pleural mesothelioma presents as a diffuse malignancy that grows along tissue surfaces, with little distinction between malignant and non-malignant areas. This can make determining the full extent of tumor infiltration difficult to properly image. CT is the standard technology in diagnostic imaging for mesothelioma and MRI can be used to supplement its results, but these technologies have known limitations in determining a number of important tumor states, including tumor involvement of the chest wall and diaphragm, as well as a fundamental inability to identify distant metastatic events or to determine lymph node status. PET can be used to identify distant metastases, but it has poor spatial resolution, so precise localization is difficult. Mediastinoscopy is used to determine the status of the mediastinal lymph nodes, but it is an invasive procedure and is limited in its ability to target all of the important lymph nodes.

Because of these difficulties, some of which are common to all cancers and some of which are specific to pleural mesothelioma, researchers have developed a number of new technologies to aid physicians in their ability to accurately diagnose and stage malignant events. One of these new systems is integrated PET/CT, which combines PET’s ability to identify distant metastases with CT’s high resolution imaging of internal anatomic structures. A number of studies on this technology’s use for mesothelioma have been published and the results have been quite promising. Continuing this researching, researchers in Denmark have recently published an article on their use of PET/CT in the preoperative staging of patients with pleural mesothelioma. In their article, “Preoperative Staging of Mesothelioma by 18F-Fluoro-2-Deoxy-D-Glucose Positron Emission Tomography/Computed Tomography Fused Imaging and Mediastinoscopy Compared to Pathological Findings After Extrapleural Pneumonectomy,” the authors demonstrate PET/CT’s advancements over CT for pre-operative staging and they recommend its greater use in the staging of mesothelioma, but they also show that it cannot replace mediastinoscopy for the analysis of nodal status.

Overview of the Study

42 patients were enrolled in the study between October 2003 and October 2006. All patients had histologically-confirmed mesothelioma, epitheloid subtype. All patients received neoadjuvant chemotherapy prior to their staging assessments, which were conducted by CT and PET/CT. The results of the scans were interpreted separately and blinded from the other. Patients whose PET/CT results indicated any non-resectable tumor infiltration of the chest wall or of structures in the mediastinum, or any evidence of distant metastases, were not given surgery, although patients whose results indicated possible N2 or N3 metastases were still referred for mediastinoscopy for histological determination of stage. If these results also showed positive N2 or N3 metastatic status, the patients did not undergo surgery.

All other patients were referred for extrapleural pneumonectomy.

The study was interested in two major topics:

1. The ability of PET/CT compared to CT to detect inoperative stages of mesothelioma; and,
2. The validity of PET/CT's results for staging, when compared against mediastinoscopy and final staging determined at EPP

Results

CT vs. PET/CT for Preoperative Staging

The results of the CT vs. PET/CT analysis showed a clear benefit to PET/CT. Of the 42 patients who were screened, PET/CT discovered: T4 disease in 7 patients, while CT did not show any; 14 patients with N2 or N3 disease, while CT only showed 7 patients; and 7 cases of distant metastases, while CT, again, did not show any. These findings resulted in an “upstage migration” of 8 cases: CT disclosed only one case as Stage IV disease, while PET/CT identified nine Stage IV cases (including the one identified by CT). In total, PET/CT excluded 12 of the 42 cases as non-resectable due to T4/M1 status, while CT did not exclude any.

PET/CT vs. Mediastinoscopy

PET/CT identified 30 patients with potentially-resectable disease. Of these patients, 14 indicated possible N2/N3 status, but they were not excluded from surgical consideration without histological confirmation of the findings. All 30 patients were then referred for mediastinoscopy. 6 patients demonstrated histologically-confirmed N2 metastases, which reduced the number of patients eligible for extrapleural pneumonectomy to 24.

All of these patients then received an EPP.

PET/CT vs. Final EPP Staging Results

Of the 24 patients who underwent EPP, 2 had undiagnosed T4 disease that PET/CT missed. T-stage was lower in 1 patient, equal in 13 and higher in 10. These results led to the following stage migration: percentage of patients identified as Stage I was reduced from 63% to 21%, while Stage IV patients increased from 4% to 12%. When compared to both mediastinoscopy and EPP staging, PET/CT correctly identified a number of N-stage cases, but it was also less accurate then both: it under-staged 3 patients when compared to mediastinoscopy and 7 when compared to final staging completed during EPP.

Conclusion

Mesothelioma remains a very difficult disease to treat effectively, and only a subset of patients are eligible for the invasive procedures that are necessary to possibly extend survival times for the disease. The need for accurate staging technologies is not unique to the treatment of pleural mesothelioma, but the difficulties of the disease complicate it. CT has been used, but it has well-known limitations for mesothelioma staging. PET/CT has showed great promise in other studies and the authors of the article describing the present study conclude that PET/CT is an important advancement in the surgical staging of pleural mesothelioma, but that it doesn’t alleviate the need for invasive, yet more accurate, diagnostic techniques such as mediastinoscopy. PET/CT can improve the selection of patients for EPP, especially when compared with CT, but the authors state that more work needs to be done to develop more accurate, non-invasive techniques.

Labels: mesothelioma, pleuralmesothelioma, staging

The current system for staging cases of pleural mesothelioma is based on a TNM model, where the determination of disease stage is based on the relationship between tumor status (T stage), lymph node status (N stage) and the presence or absence of distant metastases (M stage). This system was proposed in 1995, validated through a number of reports and subsequently accepted as the standard mesothelioma staging system by the American Joint Committee on Cancer Staging System, as well as by the Union Internationale Contre le Cancer.

However, a number of questions regarding its underlying classification structure have existed since it was initially proposed. Writing in the journal The Journal of Thoracic and Cardiovascular Surgery, physicians from the Memorial Sloan-Kettering Cancer Center (MSKCC) in New York City state that the current staging system was designed to be adjusted as more and better data regarding the classification of nodal status was developed. The authors of the article note that the staging system uses the lymph node map developed for lung cancer staging, but that pleural mesothelioma may require a different pattern map because lymphatic drainage from the pleura may differ from that of the lung.

To answer these questions, as well as others regarding the nodal classification system in mesothelioma patients, the physicians from MSKCC conducted a study on patients with pleural mesothelioma who were treated at their institution and they have recently published their results in an article entitled “The Impact of Lymph Node Station on Survival in 348 Patients with Surgically Resected Malignant Pleural Mesothelioma: Implications for Revision of the American Joint Committee on Cancer Staging System.”

Overview of the Study

The staging system is only applicable to surgical patients, so the retrospective study that the physicians conducted was limited to those patients who underwent either extrapleural pneumonectomy (EPP) or pleurectomy/decortication (P/D). 348 patients were finally selected for analysis. The sample population, as is common with all forms of mesothelioma, was heavily male gender with the epitheloid histological subtype. 222 patients received EPP, while 126 underwent P/D. Most patients were Stage III at time of surgery.

These patient records were analyzed on a number of fronts, including nodal status (both individual and concurrent metastases), common nodal station involvement, surgical procedures and time to survival.

Results

Overall median survival for the entire patient cohort was 15 months, with significant variations in survival when patients were analyzed for differences in nodal status, as well as histological subtype and overall stage. Patients with N0 or N1 status demonstrated a 19-month median survival time, while patients positive for N2, N2/N1 or internal thoracic node metastases demonstrated a 10-month median survival. Patients with only N2 status did not differ significantly from patients who were positive for both N2 and N1, but multiple N2 nodal stations were indicative of more restricted median survival time.

Other variations in survival were also reported: epitheloid vs. non-epitheloid histology, with non-epitheloid disease associated with worse survival; male gender vs. female gender, with men demonstrating a worse prognosis then women; Stage III/IV patients were associated with shorter survival than were Stage I/II patients.

Conclusion

In the discussion section of the article, the authors considered the importance of their findings in relation to the current staging system. Their results show that pleural mesothelioma is most likely to metastasize to N2 nodes, rather than to N1 nodes. The authors also note that because patients positive for only N1 nodes were associated with longer median survival than were patients positive any form of N2 metastases, the staging system should likely be changed to incorporate this distinction.

These results also confirmed an earlier study these physicians conducted which found that nodal metastasis is common in patients with pleural mesothelioma—nearly 50% of the patient cohort demonstrated some lymph node involvement.

Along with the differences in survival between N1 and N2 status, the results also demonstrated that metastases in multiple N2 nodal stations correlates with a worse prognosis than does N2 status in only one station. Because of this, the authors also state that the staging system could possibly be adjusted to show that multiple N2 stations reflect a higher stage than does a single N2 station.

The authors close the article with a call for larger study on the impact of nodal status on mesothelioma prognosis. Their research indicates grounds for revision of the staging system, but a larger, multicenter study would be needed to confirm these findings.

Labels: mesothelioma, pleuralmesothelioma, staging

Advances in our ability to diagnose mesothelioma in its earlier stages are among the most important developments in the recent fight against the disease. Along with the development of more effective treatment agents, these diagnostic advances have allowed physicians to begin treatment earlier than they have previously been able to—which is a key factor in their ability to extend patient survival and to improve issues related to a patient’s quality-of-life.

These advances in these diagnostic and treatment techniques have been the result of innovative research into the disease’s underlying biological activity. As scientists and physicians have learned more about mesothelioma, they have also been able to identify prognostic indicators that have enabled them to better identify the patient classes that will respond best to aggressive treatments and those whose disease requires a more palliative therapeutic protocol. This distinction is important because aggressive treatment protocols require highly invasive surgical techniques and a significant recovery time, so patients who present with specific disease characteristics that indicate poor treatability should not be burdened with such regimens.

The quest to identify more precise prognostic indicators for mesothelioma patients has taken many forms and the variety of research that is being conducted shows the interest that international researchers are now taking in studies of pleural mesothelioma and peritoneal mesothelioma. The latest example of this research is a paper that that has been published from researchers in Turkey. In an articled entitled “Pleural Fluid Findings as Prognostic Factors for Malignant Pleural Mesothelioma,” published in the Journal of Clinical Laboratory Analysis, they report the results of a retrospective study they conducted that analyzed the characteristics of pleural fluid in patients with pleural mesothleioma for any prognostic indicators it may contain regarding overall patient survival.

Overview of the Study

The researchers report that only one previous study had analyzed pleural fluid for its prognostic benefits, but only 26 patients had been enrolled in that study. In this study, they examined 71 patient records. There were 33 males and 38 females in the study population, with a mean age of 59 years. 23 people were smokers. Even though smoking has not been shown to have any causative affect on mesothelioma genesis, it is known to be a causative factor for a number of other cardiovascular diseases.

The patients were diagnosed by cytological or histological analysis, usually with a immunohistochemical panel that tested for combinations of calretinin, epithelial membrane antigen (EMA), thrombomodulin, HBME-1, CD15, B72.3 or carcinoembryonic antigen (CEA). Pleural fluid was analyzed for a number of specific characteristics, including pleural fluid glucose levels, lactate dehydrogenase (LDH), albumin, protein-to-serum levels and pleural fluid leukocyte counts. For their reported survival figures, the authors defined survival from date of thoracentesis to time of death.

Results

When the authors analyzed the results of the entire patient cohort, they found two independent prognostic factors that were indicative of survival: the ratio of pleural fluid to serum LDH > 1.0 and total leukocyte count in the fluid. They found a mean leukocyte count of 648+-860/mm³ for the entire cohort, but a significant increase in survival for those patients with a count of >700/mm³. When patients who used diuretics were excluded from these results, they found that fluid glucose levels also achieved statistical significance as a predictor of survival.

Conclusion

This study has indicated another set of prognostic tests that physicians can use in their determination of survival and overall prognosis for patients with pleural mesothelioma. These results will need to be independently verified before their scientific and medical value can be fully validated, but this study provides valuable information about specific biological factors involved with mesothelioma. The authors also note that the low leukocyte mean suggests a “weak inflammatory reaction against the tumor” and they suggest the “stimulation of antitumor response” is a possible treatment avenue for mesothelioma patients.

Labels: diagnosis, mesothelioma, pleuralmesothelioma

Radiotherapy is not a general modality in the treatment of mesothelioma because the diffuse nature of the disease’s invasion pattern rarely presents a localized malignancy for the radiation to be applied to. Due to mesothelioma's widespread appearance, the radiation would have to be delivered over a very wide area at very high doses to be effective, but this would put vital organs such as the lungs, heart and kidneys at serious risk for radiation overexposure and sickness. There is, however, a very specific use of radiotherapy that has shown some efficacy in the treatment of pleural mesothelioma and peritoneal mesothelioma: localized application of radiation to drain sites and other instrumentation sites after treatment, or other medical intervention.

Metastases to areas of surgical intervention are a common problem in the treatment of a number of different cancers, but the problem seems especially acute with mesothelioma treatments. Different studies have reported different figures on the likelihood of this occurring, but most estimates report a 20-50% of chance of surgical site metastases following treatment. Prior studies have reported on the benefits of radiotherapy to prevent tumor seeding, but the treatment is still not deployed in many cases and research into this question continues on a number of fronts.

An article has recently been published in the journal Acta Oncologica that describes the results of a study conducted by Italian physicians on their use of radiation to prevent drain site metastases. That article will be summarized in the following sections.

Overview of the Study

To investigate the efficacy of radiation therapy for the prevention of tract site metastases in patients treated for pleural mesothelioma, the authors enrolled 32 patients with histologically-confirmed mesothelioma into their study. There were 24 men and 8 women, with the average age at diagnosis listed at 64 years-old. 25 patients presented with epithelial mesothelioma, 6 with sarcomatoid mesothelioma and there was 1 case of the biphasic subtype. When the patient cohort was analyzed by stage at time of diagnosis, the authors found that 2 patients were considered Stage IA, 3 patients were considered Stage IB, 20 patients were listed as Stage II, 4 presented as Stage III and 3 others as Stage IV.

The patients underwent a variety of procedures in their diagnosis and treatment: some were palliative in their intent, while others were curative, but all involved some type of surgical intervention, from the insertion of drainage tubes to radical pleurectomy to other procedures as well. After their wounds healed from the original operations, all of the patients then received radiation therapy to each area that was treated by the procedure. 21Gy were delivered in three daily fractions to each patient. After the completion of treatment, 20 patients received some form of chemotherapy.

Patients received clinical examinations every 3-4 months during the first two years of treatment and then at 6-8 months following the initial two-year period.

Results

The authors were quite pleased with the results of their study. They report that “after a mean follow-up of 13.6 months...from the end of radiation therapy, no patient developed subcutaneous nodules in the treated area.” They also report that the therapy was well tolerated, with 11 patients developing a temporary grade I erythema, which is a reddening and swelling of the skin, but seemingly nothing more serious and no late treatment effects were seen.

The one year survival for the patient cohort was reported as 68.9% and the two-year rate was reported as 30.3%—both of which are excellent results for pleural mesothelioma patients. 17 patients (52%) died of mesothelioma due to local progression after a mean survival of 12.6 months. The authors note that 13 patients (41%) are still alive after a 13.9 month mean follow-up and two others are alive “without evidence of disease after a mean follow-up of 16.5 months.”

Conclusion

Because of the results of their study, the authors conclude that radiotherapy following therapeutic treatment of pleural mesothelioma is an effective methodology to prevent tumor seeding in areas of surgical intervention. They note that although this procedure has not yet been incorporated into standard treatment protocols, their results, as well as the results of a number of other studies, demonstrate radiation therapy’s benefits for the treatment of mesothelioma and they propose that it be deployed as a standard therapy.

Labels: mesothelioma, pleuralmesothelioma, radiation, treatments

Italian biotechnology company MolMed has recently announced that ARENEGYR, its experimental anti-cancer drug that is being investigated for the treatment of mesothelioma and a number of other cancers, has been granted orphan drug status from the US FDA. This announcement follows on a similar designation given by the EU’s pharmaceutical regulatory agency in June. Orphan drug status is available to investigational treatment agents that focus on uncommon and/or rare diseases, specifically defined as pathologies that affect less than 5 in 10,000 people, and it confers a number of benefits to the manufacturer to reward their research.

Malignant pleural mesothelioma remains a very difficult disease to treat effectively. Even though contemporary multimodal treatment protocols have increased median survival time, the disease is still not curable, so research into more effective therapeutics continues on a number of fronts. ARENEGYR represents one of the most promising avenues of contemporary research. It is a vascular targeting agent that selectively targets and binds with a tumor’s blood vessels. Its mechanism of action is governed by two major elements: NGR, a “tumor homing peptide” that allows this binding to occur, and TNF, a cytokine known for its ability to trigger apoptosis, which is the principal mechanism for ARENEGYR’s antitumor activity.

Along with its proposed use for mesothelioma treatment, ARENEGYR is being investigated in single agent therapy for the treatment of colorectal cancer, hepatocellular carcinoma and small-cell lung cancer. Molmed is also exploring ARENEGYR in combination with cisplatin for mesothelioma treatment and with Xelox for colorectal cancer.

Labels: chemotherapy, mesothelioma, pleuralmesothelioma, treatments

Even as improvements in the therapies available for mesothelioma patients have been made in recent years, the disease remains without cure. Most patients are ineligible for curative surgeries, so investigations into improving the efficacy of chemotherapy are among the most common research programs in contemporary mesothelioma treatment studies. Combination chemotherapy using pemetrexed and cisplatin (Alimta therapy) is considered first-line chemotherapy because it has demonstrated the most effective improvement in median time of survival when compared to every other chemotherapy regimen that has been tried. However, at some point during treatment, the disease always takes the upper hand and the chemo’s attempt to control the mesothelioma becomes more and more ineffective, until the drugs are no longer able to restrict the disease at all. When this happens in other cancers, one of the standard responses is for an oncologist to attempt another course of chemotherapy using different agents. This type of treatment regimen is known as second-line chemotherapy. Unfortunately, research has not yet identified an effective second-line chemotherapy regimen for pleural mesothelioma. Even as research into it continues, most results have been disappointing.

A group of renowned mesothelioma specialists has recently released the results of a study they conducted in hopes of identifying an effective second-line chemotherapy for pleural mesothelioma. Their study investigated the use of erlotinib plus bevacizumab for this purpose and their results have recently appeared in the journal Cancer.

This article is a summary of their findings.

Overview of the Study

A number of different agents and treatment regimens have been studied for the second-line use of chemotherapy in pleural mesothelioma patients. No standard has been identified though, so research into this question continues in hospitals around the world. Much of this research is being conducted based on our growing understanding of the biological foundations of the disease.

Some studies have demonstrated that vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) are important co-factors in the growth and spread of mesothelioma, so the authors of the present study investigated whether agents that inhibit these growth factors would be effective for treatment of the disease. Erlotinib is an inhibitor of EGFR, while bevacizumab inhibits VEGF. Combination therapy using these agents has been shown to have clinical efficacy as second-line treatment for non-small cell lung cancer and the physicians were hopeful that it would demonstrate similar efficacy for pleural mesothelioma.

The treatment plan under study called for the daily administration of 150 mg of erlotinib and for the administration of 15 mg/kg of bevacizumab on Day 1 of a 21-day cycle. Patients would be assessed for individual reactions to the treatment at each administration, while tumor assessment would be conducted through CT every two cycles.

Results

A total of 24 patients were included in the final study. As in most mesothelioma-related studies, the majority of those studied were older Caucasian men. There were 15 men and 9 women, with an average age of 62.5 years. 23 of the patients were white and one was Hispanic. 8 of the patients began the study with a performance status of 0 and 16 began it with PS of 1. The authors report on a number of other breakdowns and classifications as well.

The overall results of the treatment were disappointing. This chemotherapy regimen was not nearly nearly as effective for mesothelioma patients as it was for patients with non-small cell lung cancer. There were no complete or partial responses, but temporary stable disease was achieved in 12 patients. The other 12 patients had had progressive disease throughout the study. Of the 12 patients who demonstrated stable disease, 7 (of 8) were from the group with the best performance status (0) and 10 (of 16) presented with epithelial mesothelioma, the form of the disease with the best prognosis.

The patient cohort demonstrated a median time-to-progression of 2.2. months and a median survival time of 5.8 months. When studied at 6- month and 12- month intervals, the time-to-progression percentages were 29% and 6%, respectively, and the survival rate percentages were 46% and 24%, respectively.

Conclusion

Because of mesothelioma’s unique behavior pattern, chemotherapy remains the most commonly deployed treatment modality and this situation is unlikely to change in the near future. Advancements in the available therapies have already led to increased survival time, but more research is needed before medicine truly turns the corner on its ability to effectively treatment pleural mesothelioma. Even though this study did not demonstrate any clinical efficacy, other studies have identified alternative agents as possible treatment candidates and results from those investigations are eagerly awaited by doctors and patients alike.

Labels: chemotherapy, mesothelioma, pleuralmesothelioma, treatments

Researchers have identified a number of factors in a patient’s presentation with mesothelioma that serve as important indicators of the disease’s treatability and overall prognosis. Two of the most significant indicators are the gender of the patient and the histological subtype of the disease. In terms of gender, studies have shown time and time again that men are more likely to be given a limited prognosis than are women. Regarding histology, other studies have shown that patients who are diagnosed with epitheloid mesothelioma have a better prognosis—in some cases, a much better prognosis—than do patients who are diagnosed with either biphasic mesothelioma or sarcomatoid mesothelioma, which are the other subtypes of the disease. This information is important to mesothelioma physicians as they develop individualized treatment plans because the particular forms these indicators take will dictate one particular therapy over another.

Even as researchers have confirmed the importance of these factors in numerous trials, they have also investigated if other presentational features can function in a similar manner. A feature of particular interest to physicians involves the relationship—if any—between overall asbestos burden and treatment outcomes. Researchers have known for almost one hundred years that asbestos is the only cause of mesothelioma and that longer exposures to its dust and particulate matter, especially in occupational settings, often correlate with a greater likelihood of developing the disease, but few quantitative studies have been completed that specifically addressed the relationship between asbestos burden and treatment outcome.

In response to this, a group of researchers from some of the finest hospitals and mesothelioma research programs in the United States conducted a study that addressed this question and have recently published their findings in the journal Environmental Health Perspectives.

This article is a summary of their findings.

Overview of the Study

To address the question of the relationship between asbestos burden and mesothelioma prognosis, the study looked at a population of 128 pleural mesothelioma patients that were treated in the International Mesothelioma Program at Brigham and Women’s hospital in Boston, MA. To analyze asbestos burden, the researchers used two sets of data: self-reported data from individual patients, or data given during interviews with a trained industrial hygienist, on their occupational histories and known asbestos exposures, as well as an analysis of actual lung and tumor tissue that was removed from the patients during surgery. Reported data was available for all 128 patients, while the tissue samples were available for 83 patients.

The researchers looked at a number of factors in relation to this data, including overall asbestos exposures, actual body burden of asbestos fibers, tumor characteristics and patient demographics. Each piece of information was analyzed singularly and in combination with the other factors.

Results

In the cohort of 128 patients, there were 98 males and 38 females, with a mean age of 62 years. There were 91 cases of epitheloid mesothelioma, 33 cases of biphasic mesothelioma and 4 sarcomatoid cases. When the researchers compared the relationships between histology and gender with survival time, they again confirmed the efficacy of these two factors as important indicators of survivability: epitheloid types were associated with significantly better survival times than the other histological types, and longer survival times were demonstrated, on average, by more women than men.

To compare asbestos burden levels between individuals, the researchers used the patient’s reported data as well as data from an analysis of actual tissues (when such tissues were available). They analyzed multiple samples from resected lung tissues to determine the number of asbestos bodies per gram of tissue (ABs/g lung). The median level for the entire cohort was 158 ABs/g lung. Three individuals demonstrated a radically higher ABs/g lung figure than all other patients, so their information was not included in any of the reported statistics. The researchers also created a three-tiered structure that identified different levels of exposure and categorized those levels using the following: low burden (0-99 ABs/g lung), moderate burden (100-1099 ABs/g lung) and high burden (> 1099 ABs/g lung).

The researchers did not find an overall relationship between self-reported asbestos exposures and survival times, but they did find a relationship between older age at diagnosis of mesothelioma and self-reported exposures. An analysis of asbestos body burden levels between genders showed that men had significantly-higher median fiber levels than did women (219 vs 20 ABs/g lung), which is not surprising given the greater number of men who worked in occupations with products containing asbestos.

When the researchers compared actual tissue burden levels to survival times, they were quite surprised to learn that burden level and survivability did not progress in a linear fashion. Instead, they found that those with moderate levels of exposure survived longer, on average, than those with low or high burdens. The researchers were not able to determine the reason why the low burden group demonstrated a greater risk of shorter survival than did the moderate burden group, but they suggest that if certain individuals have a natural susceptibility to the disease then they may be susceptible to a more aggressive form of it as well.

The researchers did find, however, a significant correlation between the high asbestos burden category and shorter survival times compared to the other two levels.

Conclusion

The researchers conclude that asbestos burden could be an important factor in mesothelioma prognosis, but they state that more research studies involving larger sample populations are necessary before a final determination can be established. Mesothelioma, especially its most common form of pleural mesothelioma,is a difficult disease to manage effectively and still remains an enigma in many ways. It is through the innovative research of dedicated physicians and scientists that we’ve learned all that we currently know about this terrible disease and it is through the continual renewal of this research that we’ll learn even more.

Labels: mesothelioma, pleuralmesothelioma