Intensity modulated radiation therapy after extra-pleural pneumonectomy for malignant pleural mesothelioma is feasible without fatal pulmonary toxicity and provides good survival

AIM

To analyze patterns of failure, toxicity, relapse-free survival (RFS), and overall survival (OS) in malignant pleural mesothelioma (MPM) patients treated with intensity-modulated radiation therapy following extrapleural pneumonectomy (EPP).

METHODS

We reviewed 18 charts of patients with MPM from 2005 to 2014 who underwent EPP followed by hemithoracic intensity-modulated radiation therapy. Intensity-modulated radiation therapy dose delivery adhered to published lung dose constraints. Kaplan-Meier curves were used to assess the RFS and OS. Median survival times are reported for both RFS and OS.

RESULTS

Median age was 65 years (range: 40-76 years). Chemotherapy was administered in four neo-adjuvant and seven adjuvant patients. Pathological American Joint Committee on Cancer stages II, III, IV, surgical margin, lympho-vascular space, pericardium, and chest wall involvement were seen in 3, 12, 3, 9, 7, 12 and 3 patients, respectively. The majority of the patients received 45 Gy in 25 fractions. The mean lung dose was 7.14 Gy (range: 5 Gy-9.3 Gy). The mean V20 was 2.23%. At a median follow-up of 3 years, eight patients were alive (44%); 10 experienced relapse (56%). Median RFS and OS were 24.4 months (95% CI: >16.3 months) and 38.2 months (95% CI: 17.4-78.1 months), respectively. Acute toxicities were fatigue, dermatitis, nausea, esophagitis/dysphagia, cough, and dyspnea on exertion. No grade III, IV, or fatal pulmonary toxicities were observed.

CONCLUSION

Intensity-modulated radiation therapy following EPP for MPM resulted in RFS and OS comparable to the published literature without significant toxicity.

Role of new radiation techniques in the treatment of pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive neoplasm arising from the surface serosal cells of the pleural cavity. Surgery remains the main therapeutic standard in the treatment of MPM with the goal of complete gross cytoreduction of the tumor. Because MPM is a diffuse disease affecting the entire mesothelial lining of the hemithorax, surgery alone can rarely achieve adequate tumor-free resection margins. The surgical choices are pleurectomy/decortication (P/D) or extrapleural pneumonectomy (EPP). Radiotherapy (RT) is usually applied postoperatively with the aim to improve local control. However, the efficacy of RT is limited by the large volume of the target to be irradiated (tumor and pleural cavity) and the radiosensitivity of the nearby organs (heart, liver, lung, spinal cord, and esophagus). These factors have historically limited the effective radiation doses that can be given to the patient. There is no role for radical RT alone, but the role of RT as part of multimodality therapy is discussed. After EPP adjuvant RT to the entire hemithorax can reduce the recurrence rate and is well tolerated if strict limits to the dose to contralateral lung are applied: the V20 and V5 (the percent volume of the lung receiving more than 20Gy and 5Gy of radiation) correlate with increased lung toxicity. The use of modern sophisticated techniques allows good target coverage, more conformal high dose delivery, and clinically relevant normal tissue sparing.