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A Randomized Trial Comparing Two Fractionation Schedules for Breast Irradiation Postlumpectomy in Node-Negative Breast Cancer

William Levin, MD
OncoLink Assistant Editor
Last Modified: May 22, 2000

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,

Background:
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.

Materials and Methods:

• 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.