Invasive thymoma: postoperative mediastinal irradiation, and low-dose entire hemithorax irradiation in patients with pleural dissemination.
BACKGROUND
We evaluated the results of postoperative mediastinal radiotherapy (MRT) for invasive thymoma and low-dose entire hemithorax radiotherapy (EHRT) for pleural dissemination.


METHODS
Sixty patients were treated with a nearly uniform policy. Generally, we administered 30 to 40 Gy MRT after surgery at 2 Gy daily fractions for Masaoka stage II tumors or suspected residual diseases, and 50 to 55 Gy MRT for stage III tumors and for highly-suspected or macroscopic residual diseases. Since 1992, we have administered EHRT in patients with pleural dissemination, with 11.2 Gy in 7 fractions or 15 to 16 Gy in 10 fractions after removal of disseminated lesions in addition to MRT. We treated 52 patients with MRT alone and 8 with EHRT and MRT. In addition, we gave EHRT to four patients who developed pleural dissemination later.


RESULTS
For all 60 patients, the overall and cause-specific survival and local and pleural-dissemination control rates at 5 years were 79, 87, 86, and 69%, respectively. Both Masaoka stage and tumor resectability were associated with prognosis. In stage IVa patients, pleural dissemination control rate was 71% at 3 years after EHRT, whereas it was 49% in patients receiving MRT alone (p = 0.38). Grade 2 or higher radiation pneumonitis was observed in only 3 of 52 patients (5.8%) undergoing MRT initially. In 12 patients who underwent EHRT, 3 patients (25%) experienced grade 2 or 4 pneumonitis.


CONCLUSIONS
Postoperative MRT appeared to prevent local recurrence with acceptable toxicity. EHRT is generally safe and may contribute to control of pleural dissemination.
Sugie
Chikao
C
Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Mizuho-ku, Nagoya, Japan. chikao@bg8.so-net.ne.jp
Shibamoto
Yuta
Y
Ikeya-Hashizume
Chisa
C
Ogino
Hiroyuki
H
Ayakawa
Shiho
S
Tomita
Natsuo
N
Baba
Fumiya
F
Iwata
Hiromitsu
H
Ito
Masato
M
Oda
Kyota
K
D000328:Adult; D000368:Aged; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008482:Mediastinum / Q000000981:diagnostic imaging / Q000528:radiation effects*; D008875:Middle Aged; D009367:Neoplasm Staging; D010997:Pleural Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011379:Prognosis; D011859:Radiography; D016019:Survival Analysis; D013909:Thorax / Q000528:radiation effects*; D013945:Thymoma / Q000145:classification / Q000175:diagnosis* / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D013953:Thymus Neoplasms / Q000145:classification / Q000175:diagnosis* / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D013997:Time Factors; D016896:Treatment Outcome; D014944:World Health Organization