Multivariate analysis of pulmonary fibrosis after electron beam irradiation for postmastectomy chest wall and regional lymphatics: evidence for non-dosimetric factors.
OBJECTIVE
To evaluate the factors associated with pulmonary fibrosis after postmastectomy electron beam irradiation of chest wall and regional lymphatics in patients with breast cancer.


METHODS
From July 1987 through July 1994, 109 women with stage II and III breast cancer receiving modified radical mastectomies were managed by postoperative electron beam irradiation. Doses of 46 to 50.4 Gy were delivered to the chest wall covered with bolus, internal mammary nodes, supraclavicular nodes and axillary lymph nodes via 12 or 15 MeV single portal electron beam. Seventeen patients received additional 10-16 Gy surgical scar boost via 9 MeV electron beam. Comparison of pre-treatment and post-treatment chest X-ray films were used to monitor the development of pulmonary fibrosis.


RESULTS
Only Grade 1 radiation-induced late pulmonary toxicity was noted in 33 patients (29%). Twenty-six patients (24%) developed pulmonary fibrosis under unbolused chest wall. Lung fibrosis under bolused chest wall was noted in 11 patients (10%). Statistical difference (P<0.01) was noted between the incidence of fibrosis in these two sites. In multivariate analysis of lung fibrosis under unbolus-covered chest wall, the independent prognostic factors are low body mass index (BMI) (P<0.01), tamoxifen taking (P=0.03), and no treatment interruption (P=0.03). No independent factor was associated with lung fibrosis under bolus-covered chest wall in multivariate analysis.


CONCLUSIONS
In the analysis of pulmonary fibrosis induced by unbolused electron beam, BMI rather than body weight and body height is a strong prognostic factor. Tamoxifen and short overall time can predispose the development of lung fibrosis.
Huang
E Y
EY
Department of Radiation Oncology, Chang Gung Memorial Hospital, 123 Ta-Pei Road, Niao-Sung Hsiang, Kaohsiung Hsien, Taiwan.
Wang
C J
CJ
Chen
H C
HC
Sun
L M
LM
Fang
F M
FM
Yeh
S A
SA
Hsu
H C
HC
Hsiung
C Y
CY
Wu
J M
JM
D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D017024:Chemotherapy, Adjuvant; D016009:Chi-Square Distribution; D003520:Cyclophosphamide / Q000008:administration & dosage; D003561:Cytarabine / Q000008:administration & dosage; D004307:Dose-Response Relationship, Radiation; D015251:Epirubicin / Q000008:administration & dosage; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008198:Lymph Nodes / Q000528:radiation effects; D015412:Mastectomy, Segmental; D008727:Methotrexate / Q000008:administration & dosage; D008875:Middle Aged; D009367:Neoplasm Staging; D011446:Prospective Studies; D011658:Pulmonary Fibrosis / Q000453:epidemiology / Q000209:etiology*; D011829:Radiation Dosage; D011836:Radiation Tolerance; D018714:Radiotherapy, Adjuvant / Q000009:adverse effects; D011882:Radiotherapy, High-Energy / Q000009:adverse effects* / Q000379:methods; D012307:Risk Factors; D018709:Statistics, Nonparametric; D013909:Thorax / Q000528:radiation effects
D003561:Cytarabine; D015251:Epirubicin; D003520:Cyclophosphamide; D005472:Fluorouracil; D008727:Methotrexate