Radiation-induced bronchiolitis obliterans organizing pneumonia (BOOP) syndrome in breast cancer patients is associated with age.
BACKGROUND
Radiation-induced bronchiolitis obliterans organizing pneumonia (BOOP) syndrome is a rarely observed phenomenon characterized by infiltration of the lungs outside of the radiation field, differentiating it from radiation pneumonitis (RP).The risk factors for radiation-induced BOOP (RT-BOOP) remain unclear and controversial. We retrospectively analyzed the incidence and risk factors for RT-BOOP associated with radiation therapy (RT) after breast conserving surgery (BCS) and post-mastectomy radiation therapy (PMRT).


METHODS
We analyzed 1,176 breast cancer patients treated with RT after BCS or PMRT between March 2005 and September2008 at the cancer institute hospital of the Japanese foundation for cancer research. Chest radiographs were routinely obtained every three to six months for at least 12 months after surgery, as well as when the patients experienced respiratory symptoms or fever.


RESULTS
RT-BOOP syndrome was diagnosed in 16patients (1.4%), including12BCS patients (1.3%) and four PMRT patients (1.8%). An older age (≥52 years old) was significantly associated with the incidence of RT-BOOP syndrome in a univariate analysis (p =0.023). The type of treatment (BCS or PMRT) and irradiated lung volume at 20 Gy (V20) were not significantly associated with the incidence of RT-BOOP syndrome in the entire patient cohort. In the multivariate analysis, age and smoking were the significant factor associated with RT-induced BOOP syndrome (p =0.044 and 0.049, respectively).


CONCLUSIONS
RT-BOOP syndrome was a rarity, and the incidence for BCT cases was similar to that for PMRT cases. The irradiated lung volume was not significantly associated with RT-BOOP syndrome. An older age can predict the incidence of RT-BOOP syndrome.
Department of Radiation Oncology, University of Tsukuba, Ibaraki, Japan. keiko.nemoto@jfcr.or.jp.|Department of Radiation Oncology, Cancer Institute Hospital, The Japanese Foundation for Cancer Research, Tokyo, Japan. keiko.nemoto@jfcr.or.jp.
Keiko Nemoto
KN
Murofushi
Department of Radiation Oncology, Cancer Institute Hospital, The Japanese Foundation for Cancer Research, Tokyo, Japan. oguchi@jfcr.or.jp.
Masahiko
M
Oguchi
Department of Clinical Trial and Clinical Epidemiology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki Prefecture, Japan. mgosho@md.tsukuba.ac.jp.
Masahiko
M
Gosho
Department of Radiation Oncology, Cancer Institute Hospital, The Japanese Foundation for Cancer Research, Tokyo, Japan. takuyo.kozuka@jfcr.or.jp.
Takuyo
T
Kozuka
Department of Radiation Oncology, University of Tsukuba, Ibaraki, Japan. hsakurai@pmrc.tsukuba.ac.jp.
Hideyuki
H
Sakurai
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D018270:Carcinoma, Ductal, Breast / Q000473:pathology / Q000532:radiotherapy*; D018549:Cryptogenic Organizing Pneumonia / Q000209:etiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011379:Prognosis; D017564:Radiation Pneumonitis / Q000209:etiology*; D011878:Radiotherapy / Q000009:adverse effects*; D012189:Retrospective Studies; D013577:Syndrome; D055815:Young Adult