A Randomized Trial Comparing Two Fractionation Schedules for BreastIrradiation Postlumpectomy in Node-Negative Breast Cancer
Presenter: Timothy J. Whelan
Affiliation: Hamilton Regional Cancer Ctr, Hamilton, ON, Canada; Toronto Sunnybrook Regional Cancer Ctr, Toronto, ON, Canada; McMaster Univ, Hamilton, ON, Canada; Kingston Regional Cancer Ctr, Kingston, ON, Canada; Ottawa Regional Cancer Ctr, Ottawa,
Many women with early stage breast cancer choose lumpectomy plus definitive breast irradiation for treatment. Typically in the US, radiation is delivered to a dose of 46 - 50 Gy to the whole breast followed by a boost to about 60 Gy, all over a course of 6 weeks. This study evaluates the possibility of increasing the daily fraction size and reducing the number of treatment days by using a dose that is biologically equivalent to standard therapy.
- 1234 women with node negative breast cancer and clear surgical margins following lumpectomy were randomized to either:
Arm 1. 42.5 Gy of whole breast irradiation in 16 fractions over 22 days
Arm 2. 50 Gy of whole breast irradiation in 25 fractions over 35 days
- All treatment was delivered 5 days per week with 2 tangential fields
- No breast boost was used in this study
- Median followup was 4.6 years
- The 5-year actuarial breast recurrence rate was 2.9% in each arm.
- The 5-year diease-free survival rates were 88% vs. 90% (p=NS) in Arm 1 vs. Arm 2.
- The 5-year overall survival was 93.5% vs. 94.3% (p = NS) in Arm 1 vs. Arm 2.
- The cosmetic outcome at both 3 and 5 years was not significantly different.
- These data suggest that a shorter course of radiation is an acceptable alternative to the current standard of practice.
- Such a schedule is more attractive because it is more convenient for patients and less resource-intensive for the facility.
- In general, increasing the daily radiation dose can be associated with worse cosmetic outcome and a higher probability of normal normal tissue complications involving the heart, brachial plexus and lung.
- The control arm of this trial did not use a breast boost typically administered at most US centers.
- This study shows an equal efficacy in tumor control and cosmetic outcome between the two arms.
- The relatively short followup of this study must be taken into account when evaluating for local control, late toxicity and cosmesis.