Long-term results of hypofractionated radiation therapy for breast cancer.
BACKGROUND
The optimal fractionation schedule for whole-breast irradiation after breast-conserving surgery is unknown.


METHODS
We conducted a study to determine whether a hypofractionated 3-week schedule of whole-breast irradiation is as effective as a 5-week schedule. Women with invasive breast cancer who had undergone breast-conserving surgery and in whom resection margins were clear and axillary lymph nodes were negative were randomly assigned to receive whole-breast irradiation either at a standard dose of 50.0 Gy in 25 fractions over a period of 35 days (the control group) or at a dose of 42.5 Gy in 16 fractions over a period of 22 days (the hypofractionated-radiation group).


RESULTS
The risk of local recurrence at 10 years was 6.7% among the 612 women assigned to standard irradiation as compared with 6.2% among the 622 women assigned to the hypofractionated regimen (absolute difference, 0.5 percentage points; 95% confidence interval [CI], -2.5 to 3.5). At 10 years, 71.3% of women in the control group as compared with 69.8% of the women in the hypofractionated-radiation group had a good or excellent cosmetic outcome (absolute difference, 1.5 percentage points; 95% CI, -6.9 to 9.8).


CONCLUSIONS
Ten years after treatment, accelerated, hypofractionated whole-breast irradiation was not inferior to standard radiation treatment in women who had undergone breast-conserving surgery for invasive breast cancer with clear surgical margins and negative axillary nodes. (ClinicalTrials.gov number, NCT00156052.)
Whelan
Timothy J
TJ
McMaster University and Juravinski Cancer Centre, Hamilton, ON, Canada. tim.whelan@jcc.hhsc.ca
Pignol
Jean-Philippe
JP
Levine
Mark N
MN
Julian
Jim A
JA
MacKenzie
Robert
R
Parpia
Sameer
S
Shelley
Wendy
W
Grimard
Laval
L
Bowen
Julie
J
Lukka
Himu
H
Perera
Francisco
F
Fyles
Anthony
A
Schneider
Ken
K
Gulavita
Sunil
S
Freeman
Carolyn
C
D001940:Breast / Q000033:anatomy & histology / Q000528:radiation effects*; D001943:Breast Neoplasms / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery; D019583:Dose Fractionation, Radiation; D004954:Esthetics; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D057194:Intention to Treat Analysis; D053208:Kaplan-Meier Estimate; D015412:Mastectomy, Segmental; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology; D016016:Proportional Hazards Models; D018714:Radiotherapy, Adjuvant / Q000009:adverse effects / Q000379:methods; D016896:Treatment Outcome