[Clinical and pathological profile of the pleural malignant mesothelioma: A retrospective study about 30 cases]

BACKGROUND

The malignant pleural mesothelioma (MPM) is a rare tumour usually associated to asbestos exposure. The delay between the exposure and the occurrence of the cancer can reach 40 years. This caused the pick of incidence described in many countries including Tunisia. The diagnosis is suspected based on clinical features but positive diagnosis is microscopic. Our aim was to describe the clinical and microscopic features of MPM through a single institution experience.

PATIENTS AND METHODS

We conducted a retrospective study about 30 MPM diagnosed over a 20-year-period (1995-2015). We included only patients with complete records including clinical, radiologic and microscopic features. All the microscopic diagnoses were reviewed by 2 pathologists. A mean of 12 slides per case was reviewed. The diagnosis was based on the 2015 WHO classification.

RESULTS

The mean age of the patients was 61 years, average 22 to 80 years. The sex ratio was 6,5. An asbetose exposition was reported in 21 cases. The most frequent symptoms was chest pain reported in 25 cases. Physical exam was normal in 9 cases. It revealed pleural syndorm in most patients (60 %). Imaging findings consisted mainly in diffuse pleural thickening in 17 cases. Twelve tumours were classified as stage I, 3 stage II, 14 stage III et 1 stage IV. Pleural biopsy was performed using needle in 18 cases, through thoracoscopy in 16 cases, thoracotomy in 3 cases and allowed the diagnosis in respectively 7 cases/18, 16 cases/16 and 3 cases/3. A lymph node biopsy was performed through mediastinoscopy in one case and yelded the diagnosis. The diagnosis was performed on surgical specimen in 2 patients: one bullectomy and one right upper lobectomy. The microscopic exam concluded to an EM in 17 cases, sarcomatoid mesothelioma (SM) in 4 cases and biphasic mesothelioma (BM) in 9 cases. Pan-cytokeratin antibody was used in all cases in association with 2 antibodies with positive diagnostic value and 2 antibodies with negative diagnostic value. It was repeated in 15 cases and the most used antibodies were the anti-calretinin and the TTF1. This was due to the lack of fixation in one case and in order to reach a quality criteria in the other cases. Surgical resection was possible in 2 patients. 15 patients were lost of view after a mean follow-up period of 3 months. Thirteen patients died before or during the follow-up.

CONCLUSION

This work was about a Tunisian experience in the diagnosis and management of MPM. The major limits faced were the incomplete databases, the small number of patients included. Microsocpic positive diagnosis necessitates a degree of expertise and every laboratory has to determine the most valuable antibodies through its experience in order to optimize the diagnosis and to reduce the delay of diagnosis.

[Malignant pleural mesothelioma: The role of surgery]

INTRODUCTION

Malignant pleural mesothelioma (MPM) is a rare and highly aggressive disease, whose incidence is increasing. Asbestos is the primary causal agent.

STATE OF KNOWLEDGE

Knowledge about MPM has evolved. Thoracoscopy is essential for diagnosis of MPM. It allows performing pleural biopsies, to study the extent of the disease and to relieve dyspnea. The pathological diagnosis is also better codified with immunohistochemistry and with analysis by expert of Mesopath group. Curative surgical treatments are pleurectomy decortication and extended pneumonectomy in combination with chemotherapy and/or radiotherapy. Those heavy treatments improve survival in highly selected patients. For the other patients, supportive measures will be considered to reduce pain and dyspnea.

PROSPECT

Radical surgical treatment is only offered in therapeutic trials or multimodal treatment. Its place is not formally established. New therapies associated to surgical treatment are being studied.

CONCLUSIONS

Surgical management of MPM has to be operated in specialized teams where the survival benefit and quality of life is discussed case by case.

[Anti-tumor immunotherapy in malignant pleural mesothelioma]

INTRODUCTION

Malignant pleural mesothelioma (MPM) is a quite rare cancer, but with increasing incidence, that is usually induced by previous asbestos exposure. Its prognosis is poor and there is no validated curative therapy to date. Surgery of MPM, done only by few expert teams within a multimodal treatment is of limited and still disputed value. The standard treatment of MPM, relying on first-line chemotherapy by combined cisplatin-pemetrexed is often poorly effective, even if combination with bevacizumab anti-VEGF antibodies has slightly improved the results. Moreover, no second line treatment is recommended in case of failure of this chemotherapy. Therefore, the search of new therapies or strategies is crucial and the recruitment of patients in clinical trials is highly encouraged.

BACKGROUND

Among the treatments under investigation, various anti-tumour immunotherapies, in particular immune checkpoints inhibitors (ICI), currently exhibit the most promising preliminary results. First data from the phase II, randomized "IFCT MAPS-2", recently presented during the 2017 ASCO meeting, confirmed the value of ICI in MPM patients in cases of chemotherapy failure.

OUTLOOK AND CONCLUSIONS

However, several exciting immunotherapies other than ICI are presently being evaluated in MPM and are reported in this article. Moreover, many questions still need to be answered about immunotherapy: what is its potential value as first line treatment? How to target the best candidates for these treatments? Which combinations between immunotherapy and standard chemotherapy, targeted therapies, surgery or radiotherapy? Finally, it is now essential that every clinician has sufficient knowledge about the possible toxicities of immunotherapy.

[Prophylactic radiotherapy in a single fraction of 10Gy at intervention pleural site in patient with malignant pleural mesothelioma: A retrospective monocentric cohort study]

PURPOSE

Prophylactic radiotherapy to prevent procedure-tracts metastases from malignant pleural mesothelioma remains controversial and clinical practice varies. The purpose was to assess the efficacy of local radiotherapy in a single fraction of 10Gy in preventing malignant seeding at intervention pleural site in patients with malignant pleural mesothelioma.

MATERIAL AND METHODS

This is a retrospective cohort study, including patients with histological confirmed malignant pleural mesothelioma treated by prophylactic irradiation to prevent interventional site metastases with a unique fraction of 10Gy with 6 to 18MeV, from January 1990 to December 2013 in the institut de cancérologie de Lorraine (Nancy, France).

RESULTS

Ninety-one patients were treated by irradiation in intervention site, involving 120 intervention pleural sites, 91 thoracoscopies, 17 thoracotomies with chest drain and 12 CT or ultrasound guided needle biopsies. The median follow-up was 7 months (interquartile between 3 and 15 months). The overall survival was 43.5% at 12 months. The local progression free survival was 43.7% at 12 month. The incidence of local recurrence was 8% at 12 months. The median interval from radiotherapy to local recurrence was 4 months (2; 32). No grade II or higher toxicity was observed.

CONCLUSION

Irradiation of pleural intervention sites with a single fraction of 10Gy is effective, well tolerated, simple, fast and cost effective.

High dose irradiation after pleurectomy/decortication or biopsy for pleural mesothelioma treatment

PURPOSE

The role played by radiation therapy after pleurectomy/decortication or surgical biopsy in malignant pleural mesothelioma is uncertain. We treated patients with accelerated hypofractionated radiotherapy using helical tomotherapy and intensity-modulated arc therapy in an attempt to keep lung toxicity to a minimum. The present study reports the feasibility and toxicity of this approach.

MATERIAL AND METHODS

Between 2008 and 2012, 36 patients with malignant pleural mesothelioma underwent accelerated hypofractionated radiotherapy to the hemithorax after pleurectomy/decortication (19 patients) or biopsy (17 patients). The prescription dose was 25Gy in five fractions over 5 consecutive days.

RESULTS

We observed three patients with G3 pneumonitis, five cases of grade 2 dyspnea and six cases of grade 2 cough. The median follow-up was 37 months (range: 3-54 months). The median overall survival for patients who underwent pleurectomy/decortication followed by radiotherapy was 21.6 months [95% confidence interval (95% CI): 15.5-24.1] compared to 19.4 months for patients not submitted to surgery.

CONCLUSION

Treatment of intact lung with pleural intensity-modulated arc irradiation in malignant pleural mesothelioma patients with malignant pleural mesothelioma proved safe and feasible, with an acceptable rate of pneumonitis. Survival rates were encouraging for both biopsy-only and pleurectomy/decortication groups. We are currently conducting a phase II dose escalation trial in a similar patient setting to prospectively evaluate the impact of radiotherapy on toxicity, disease-free survival and overall survival.

[Helical tomotherapy in the treatment of malignant pleural mesothelioma: The impact of low doses on pulmonary and oesophageal toxicity]

PURPOSE

To evaluate the adjuvant treatment of malignant pleural mesothelioma by helical tomotherapy and the impact of low doses on esophageal and pulmonary toxicity.

PATIENTS AND METHODS

Between June 2007 and May 2011, 29 patients diagnosed with malignant pleural mesothelioma received adjuvant radiotherapy by helical tomotherapy. The median age was 63 years (34-72). Histologically, 83 % of patients had epithelioid malignant pleural mesothelioma. Clinically, 45 % of patients were T3 and 55 % N0. Eighty six percent of the patients were treated by extrapleural pneumonectomy and 35 % received neoadjuvant chemotherapy with platinum and pemetrexed. The median dose in the pneumonectomy cavity was 50Gy at 2Gy/fraction.

RESULTS

The mean follow-up was 2.3 years after diagnosis. Overall survival at 1 and 2 years was 65 and 36 % respectively. The median survival from diagnosis was 18 months. Median lung volumes receiving 2, 5, 10, 13, 15 and 20Gy (V2, V5, V10, V13, V15 and V20) were 100, 98, 52, 36, 19 and 5 %. The median of the mean remaining lung dose was 11Gy. Two patients died of pulmonary complications, three patients had grade 3 lung toxicity, while esophageal grade 3-4 toxicity was observed in three other patients. No significant impact of clinical characteristics and dosimetric parameters were found on pulmonary toxicity, however a V10≥50 %, a V15≥15 % and mean lung dose of 10Gy or more had a tendency to be predictive of pulmonary toxicity (P<0.1). Moreover, in our analysis, the mean lung dose seems to have a significant impact on esophageal toxicity (P=0.03) as well as low doses to the controlateral lung: V5, V10 and V13 (P<0.05).

CONCLUSION

Helical tomotherapy is a promising technique in the multimodality treatment of malignant pleural mesothelioma. Low doses received by the contralateral lung appear to be the limiting factor. A dosimetric comparison with volumetric modulated arctherapy techniques would be interesting in this setting.

[Malignant pleural mesothelioma after radiation treatment for Hodgkin lymphoma]

Malignant mesothelioma is a relatively uncommon malignancy. Although the pathogenesis is primarily related to asbestos, the role of ionizing radiation is more controversial. We report the case of a 41-year-old male who developed pleural mesothelioma. He had both, a prior short asbestos exposure and a thoracic radiotherapy for Hodgkin's disease 26years before. The evidence for radiotherapy as cause for mesothelioma is expanding and the diagnosis of mesothelioma in patients who had previous irradiation should be kept in mind.