Rationale for and preliminary results of proton beam therapy for mediastinal lymphoma.
OBJECTIVE
To evaluate the potential of three-dimensional proton beam therapy (3D-PBT) for reducing doses to normal structures in patients with mediastinal lymphomas compared with conventional photon radiation therapy (RT).


METHODS
We treated 10 consecutive patients with mediastinal masses from lymphomas with 3D-PBT between July 2007 and February 2009 to 30.6-50.4 cobalt-Gray equivalents (CGE). Of those patients, 7 had primary refractory or recurrent disease, and 8 had Hodgkin lymphoma. Dosimetric endpoints were compared with those from conventional RT plans.


RESULTS
PBT delivered lower mean doses to the lung (6.2 vs. 9.5 Gy), esophagus (9.5 vs. 22.3 Gy), and heart (8.8 vs. 17.7 Gy) but not the breasts (5.9 vs. 6.1 Gy) than did conventional RT. Percentages of lung, esophagus, heart, and coronary artery (particularly the left anterior descending artery) volumes receiving radiation were consistently lower in the 3D-PBT plans over a wide range of radiation doses. Of the 7 patients who had residual disease on positron emission tomography before PBT, 6 (86%) showed a complete metabolic response.


CONCLUSIONS
In patients with mediastinal lymphomas, 3D-PBT produced significantly lower doses to the lung, esophagus, heart, and coronary arteries than did the current conventional RT. These lower doses would be expected to reduce the risk of late toxicities in these major organs.
Li
Jing
J
Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
Dabaja
Bouthaina
B
Reed
Valerie
V
Allen
Pamela K
PK
Cai
Haihong
H
Amin
Mayankkumar V
MV
Garcia
John A
JA
Cox
James D
JD
D000328:Adult; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001940:Breast / Q000528:radiation effects; D003331:Coronary Vessels / Q000528:radiation effects; D004947:Esophagus / Q000528:radiation effects; D005260:Female; D006321:Heart / Q000528:radiation effects; D006689:Hodgkin Disease / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D008168:Lung / Q000528:radiation effects; D016403:Lymphoma, Large B-Cell, Diffuse / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D016399:Lymphoma, T-Cell / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008479:Mediastinal Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy / Q000532:radiotherapy*; D058958:Organs at Risk / Q000528:radiation effects; D011522:Protons; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000009:adverse effects / Q000379:methods*; D047368:Tumor Burden
D011522:Protons