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Impact of a boost dose of 16 Gy on the local control and cosmesis in patients with early breast cancer: The EORTC boost versus no boost trial

Li Liu, MD
OncoLink Assistant Editor
Last Modified: October 23, 2000

Presenter: H. Bartelink
Affiliation: The Netherlands Cancer Institute

Summary:

Breast conservation therapy (BCT) is a standard of care in the management of patients with early stage breast cancers. BCT results have consistently shown survival equivalence to mastectomy. However, the question remains whether boost is necessary for local tumor control and what its impact is on cosmesis as part of a breast conserving therapy is still unknown. In this study, researchers at the European Organization for Research and Treatment of Cancer (EORTC) reported a phase III randomized trial evaluating the impact of a boost dose of 16 Gy on outcome of patients with early stage breast cancers.

Methods:

• In this phase III study, a total of 5318 patients with early stage breast cancers who underwent a microscopically complete excision were randomized between no boost or a 16 Gy boost following whole breast irradiation of 50 Gy.
• Median follow-up was 5.1 years.

Results:

• For all patients as a whole, younger age (< 40 years) was the single most significant predictor for local recurrence in the multivariate analysis.

• 5-year actuarial local recurrence rate was 6.8% in the no boost group as compared to 4.3% in the boost group (p<0.0001), favoring the boost group.

• There was no survival difference between the two groups.

• Cosmetic results appeared to be better in the no boost group, but the difference was not statistically significant.

Author's Conclusions:

• 16 Gy boost reduced the local recurrence by 41% (4.3% vs. 6.8%).

• 16 Gy boost resulted in a slight reduction of cosmetic outcome that was not statistically significant.

• With a median follow-up of 5.1 years, there was no difference in survival between the boost and the no boost group.

• Longer follow-up is needed to draw any definitive conclusions.