Malignant pleural mesothelioma (MPM) is a rare tumor with a poor prognosis. Treatment may include surgical resection, chemotherapy (CT), radiation therapy, or a combination of all 3. We report a descriptive retrospective study that evaluates clinical and pathological features, type of treatment, and survival in patients diagnosed with this disease in our region (Vallés Occidental, Barcelona) between 2008 and 2016.

There were 44 cases of MPM in total. Most patients were men (84%), and 56.8% were 70 years of age or older. Twenty-five patients had epithelioid type disease, 1 biphasic, 2 sarcomatoid, and 16 with no specific histology. Twenty-four (54.6%) were smokers. Nine (20.5%) had a history of asbestos exposure.

Most were in advanced stages at diagnosis, 35 (79.5%) in stages III and IV, and 9 (20.5%) in stages I and II. Twenty-three (52.3%) had performance status (PS) 0–1, and 21 (47.7%) had PS 2–3.

Surgery was indicated in 2 patients (4.5%); in 1 to limit symptoms and for disease diagnosis, and in the other due to very good response to systemic therapy and good PS in a young patient. The remaining patients were treated with talc pleurodesis. Twenty-one patients (47.7%) received first-line CT with cisplatin-pemetrexed, and 4 (9%) showed partial response or stable disease. Ten patients (47.6%) received a second line of treatment after progression, 5 (50%) with vinorelbine and 5 (50%) with gemcitabine.

Mean overall survival (OS), analyzed by the Kaplan–Meier method, was 14 months (95% CI: 11.6–16.4), with no differences between men and women (14 vs 16 months) (P=0.91). There were no significant differences in OS between patients with epithelioid tumors (15 months) and those with other histologies (14 months) (P>0.6). OS in terms of stages I/II/III/IV was 11, 15, 14 and 11 months, respectively (P>0.5). In patients treated with CT, OS was 15 months compared to 11 months in untreated patients (P>0.3).

MPM is a rare tumor that is difficult to diagnose and therapeutic options are limited. In up to 80% of cases, it is associated with occupational exposure to asbestos.1 Symptoms include the development of pleural effusion, dyspnea or pain.1

Computed tomography (CT) is the radiological diagnostic procedure of choice; it reveals diffuse pleural thickening and nodular lesions, although it lacks sensitivity in the assessment of mediastinal or contralateral involvement. The extension study can be completed with PET or a PET-CT.2 Cytological analysis of pleural fluid helps differentiate the diagnosis from metastatic tumors.1 Thoracoscopy is the technique of choice for obtaining guided biopsy samples. Better staging can be achieved with video-assisted thoracoscopy, and pleurectomy or decortication can be performed in selected cases.3 In our series, diagnosis was made using CT; the study can be completed with a PET in certain patients in whom surgery is proposed by the multi-disciplinary committee. The pathology analysis is performed on biopsies obtained by thoracoscopy or fine-needle aspiration and biopsy.

Histological types vary between epithelioid, sarcomatoid, and biphasic; other rare subtypes are desmoplastic, small cell, and lymphohistiocytoid.2

OS is estimated to be around 1 year4; in our series, it was 14 months. The benefit of surgery is controversial, as it seems to have little effect on survival in most studies, whereas associated morbidity and mortality are high.5 In 2011, Treasure et al.6 conducted a randomized study in the United Kingdom that had a high impact on clinical practice. They found no significant differences in survival, which was lower in operated patients, while interventions were associated with high morbidity and mortality. Given these results and those of other non-randomized trials, controversy regarding the role of radical surgery is rife. Ongoing studies, such as MARS2, are analyzing the role of decortication compared to radical surgery.7 The current evidence has prompted clinicians to reserve surgery for the local control of symptoms, pain, or pleural effusion.5 Surgery was indicated for the control of incapacitating pleuritic pain in 1 of the patients from our series; the other operated patient, who was young with a good PS, underwent surgery after good response to CT. Surgery was performed in these 2 highly selected patients only, taking into consideration the risk and the limited potential benefit of the intervention.

Prompt initiation of treatment improves prognosis.8 Radiation therapy can play an important role in the control of pain. OS is greater with combined cisplatin and pemetrexed9 than with single-agent cisplatin (12 vs 8–9 months).9,10 CT confers a limited increase in OS (15 months in our series), with improved control of symptoms. In case of progression, the second line of treatment can include pemetrexed as a single agent (if it was not used in first line), gemcitabine or vinorelbine.11

In addition to CT, studies with other agents have shown an improved prognosis in MPM patients. The combination of nintedanib (an anti-angiogenic tyrosine kinase inhibitor) and CT in a phase II study has shown an increase in progression-free survival, and a trend toward a longer OS compared to CT alone.12 Finally, other options currently under development for second and third-line treatment are based on anti-PD-1 agents, such as pembrolizumab13 or nivolumab, and its combination with ipilimumab, under study in a phase II trial in comparison with monotherapy.2

Despite its retrospective nature, our series provides experience in the surgical and systemic management and prognosis of a group of patients with this rare tumor. The best treatment for MPM is still to be determined. Surgery is associated with significant perioperative morbidity, and is performed only in highly selected cases in whom the risk of the procedure is understood. CT achieves a limited increase in survival, but it is associated with better control of symptoms. New systemic therapies could provide better outcomes in the prognosis of this disease.