Promising early local control of malignant pleural mesothelioma following postoperative intensity modulated radiotherapy (IMRT) to the chest.
OBJECTIVE
Malignant pleural mesothelioma often recurs locally in spite of aggressive resection by extrapleural pneumonectomy and conventional radiotherapy. This may be due to failure to recognize the extent of clinical target volume (CTV) or suboptimal dose delivery to a target that abuts the heart, esophagus, liver, lung, kidney, and spinal cord. We report how these geometric/dosimetric constraints were overcome by exploiting intensity-modulated radiotherapy in the first cohort patient.


METHODS
Twenty-eight patients who had undergone extrapleural pneumonectomy were treated with intensity-modulated radiotherapy. The CTV included the surgically violated inner chest wall, insertion of diaphragm, pleural reflections, and deep margin of the incision. CTV delineation was facilitated by intraoperative radio-opaque marking. Motion was assessed. CTV doses were 45-50 Gy with boosts taken to 60 Gy.


RESULTS
Despite the large, irregular CTV (median, 4151 cc; range, 2667-7286 cc), an average of 97% of the CTV was covered to the target dose (range, 92%-100%). Respiratory motion was minimal because of immobility of the prosthetic diaphragm. Normal tissue dose constraints were met. The commonest effects were nausea/vomiting (89%) and dyspnea (80%). Esophagitis was absent (59% of patients) or mild (34% grade 1/2). At median follow-up of 9 months (range, 5-27 months), local control within the contoured target was 100%. One-year survival, disease-specific survival, and disease-free survival are 65%, 91%, and 88%, respectively.


CONCLUSIONS
Intensity-modulated radiotherapy after extrapleural pneumonectomy is tolerable and seems effective, at least at this early point. As local control improves, systemic metastases become more common, and it may be appropriate to add novel agents to further improve the therapeutic ratio.
Ahamad
Anesa
A
Department of Radiation Oncology, Section of Thoracic Molecular Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
Stevens
Craig W
CW
Smythe
W Roy
WR
Liao
Zhongxing
Z
Vaporciyan
Ara A
AA
Rice
David
D
Walsh
Garrett
G
Guerrero
Thomas
T
Chang
Joe
J
Bell
Brent
B
Komaki
Ritsuko
R
Forster
Kenneth M
KM
D000328:Adult; D000368:Aged; D001918:Brachytherapy / Q000379:methods; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008654:Mesothelioma / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery; D008875:Middle Aged; D010997:Pleural Neoplasms / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery; D011013:Pneumonectomy / Q000379:methods; D011879:Radiotherapy Dosage; D018714:Radiotherapy, Adjuvant; D016019:Survival Analysis; D016896:Treatment Outcome