Current Readings: Improvements in Intensity-Modulated Radiation Therapy for Malignant Pleural Mesothelioma

Pleural Mesothelioma: A Rapid Evolution of an Indolent Disease

Mesothelioma is a rare and insidious neoplasm and is characterized by its highly malignant and aggressive nature. The most common etiology is asbestos exposure, but there are some reports without known asbestos exposure and other factors leading to malignant pleural mesothelioma (MPM). Here, we present the case of a 58-year-old woman with pleuritic chest pain, dyspnea, and fever on presentation to the emergency department (ED), which caused several admissions to the ED in 20 days. The patient was then admitted to the internal medicine department with a diagnosis of community-acquired pneumonia with parapneumonic effusion. During hospitalization, a positron emission tomography (PET) scan, thoracic computed tomography (CT), and pleural biopsy were performed and a final diagnosis of malignant epithelioid pleural mesothelioma was made. Six weeks after the onset of symptoms, the patient presented with an exponential disease progression, dying two months after the diagnosis, despite the initiation of chemotherapy. MPM remains a diagnostic and therapeutic challenge with a very poor prognosis. However, studies show that mesothelioma patients who undergo treatment live at least twice as long as patients who do not receive treatment. This case report is particularly significant because, although it was epithelioid mesothelioma, multiple solid masses were noted on CT and the patient exhibited rapid disease progression, dying a few weeks after starting treatment.

Overview of treatment related complications in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive malignant neoplasm of the pleura related to asbestos exposure. Despite recent advances in therapy for MPM, the prognosis remains poor, with considerable treatment associated morbidity. Radiological assessment plays a central role in the timely identification and subsequent management of treatment related complications in MPM. This review highlights common and uncommon complications associated with and encountered in the post treatment phase.

Malignant mesothelioma of the pleura with desmoplastic histology: a case series and literature review

BACKGROUND

Desmoplastic malignant pleural mesothelioma (DMM) is rare histological subtype of diffuse malignant pleural mesothelioma (MPM), accounting for 5-10 % of cases. It has a poor prognosis, with direct invasion of the chest wall or lungs and distant metastases. Its pathological characteristics include dense collagen fibers in a storiform pattern. Its pretreatment pathological diagnosis is difficult, with fibrous pleuritis and reactive mesothelial hyperplasia as potential differential diagnoses.

CASE PRESENTATION

We retrospectively reviewed the medical charts of patients with MPM from 1996 to 2012. Among 60 patients with MPM, four patients with the desmoplastic subtype were identified and their clinical characteristics, including asbestos exposure, treatment, and prognosis, were reviewed. All of the patients with DMM were men, with a median age of 69 years (range: 63-74 years). All four patients had been exposed to asbestos. The definitive diagnosis was made histologically and the International Mesothelioma Interest Group classification was advanced (III/IV: 2/3) in all four patients. Three patients were treated with chemotherapy (two with cisplatin/pemetrexed and one with cisplatin/gemcitabine) and one patient underwent surgery. The median survival time in the patients with DMM was 3.8 months (range: 0.9-11.5 months), compared with 10.5 months in patients with other subtypes of MPM in our institution.

CONCLUSIONS

DMM continues to have a poor prognosis. It is important to recognize this variant and distinguish it from pleural plaques, non-specific reactive pleural fibrosis, pleurisy, and other lung diseases.

Advances in the diagnosis, treatment and prognosis of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a rare cancer originated from pleural mesothelial cells. MPM has been associated with long-term exposure to asbestos. The prognosis of MPM is poor due to the difficulty of making diagnosis in the early stage, the rapid progression, the high invasiveness and the lack of effective treatment. Although the incidence of MPM is low in China to date, it has a tendency to increase in the coming years. The variety of clinical features may cause the delay of diagnosis and high rate of misdiagnosis. The diagnosis of MPM is based on biopsy of the pleura and immunohistochemistry. As China has become the largest country in the consumption of asbestos, it would give rise to a new surge of MPM in the future. The current treatment of MPM is multimodality therapy including surgery, radiotherapy, chemotherapy and immunotherapy. Two surgical procedures are commonly applied: extrapleural pneumonectomy (EPP) and pleurectomy/decortication (P/D). Three dimensional conformal radiotherapy is used to denote a spectrum of radiation planning and delivery techniques that rely on the 3D imaging to define the tumor. Cisplatin combined with pemetrexed (PEM) is the first-line chemotherapy for MPM. The principal targets in immunotherapy include T cells (Treg), CTLA-4 and PD-1. The diagnosis, treatment and prognosis still remain a major challenge for clinical research and will do so for years to come.

Tomotherapy improves local control and changes failure patterns in locally advanced malignant pleural mesothelioma

PURPOSE

The purpose of the study was to determine whether intensity modulated radiation therapy delivered via helical tomotherapy improves local control (LC) after pleurectomy/decortication (P/D) for malignant pleural mesothelioma compared with 3-dimensional conformal radiation therapy (3D-CRT).

METHODS AND MATERIALS

Forty-five consecutive patients were treated with adjuvant radiation to 45 Gy in 1.8 Gy fractions after P/D between 2006 and 2014; 23 received 3D-CRT, and 22 received tomotherapy. Kaplan-Meier analysis was used to calculate overall survival, time to in-field or local failure (LF), and time to out-of-field failure. The Student t test and Fisher exact test were used to detect between-group differences.

RESULTS

Median follow-up time was 19.4 months and 12.7 months for the 3D-CRT and tomotherapy groups, respectively. Eighty-two percent of patients had T3/T4 disease, and 64% had positive nodes; 17.4% and 41% of patients in the 3D-CRT and tomotherapy groups had nonepithelioid histology, respectively. Mean planning target volume dose, percentage of planning target volume receiving 100% of the prescription dose, and lung doses were significantly greater with tomotherapy (P < .05), but toxicity rates (including radiation pneumonitis rates) were equivalent. LC was significantly improved with tomotherapy on Kaplan-Meier analysis with outcomes censored at 2 years (P < .05); uncensored, this became a trend (P = .06). Median time to LF was 19 months with tomotherapy and 10.9 months in 3D-CRT (the latter interval being less than the median follow-up in the tomotherapy group). On univariate analysis, treatment modality was the only significant predictor of LC (P < .05). Isolated LF was significantly more frequent with 3D-CRT (P < .05). Conversely, isolated out-of-field failure was significantly more frequent with tomotherapy (P < .05). Overall survival and out-of-field control were not significantly different.

CONCLUSION

Tomotherapy after P/D for malignant pleural mesothelioma is associated with improved target coverage that translates into improved LC compared with 3D-CRT. This is related to a change in failure patterns, with isolated LF being more common in the 3D-CRT group and isolated out-of-field failures predominating in the tomotherapy group.