Presenter: A. Fyles Presenter's Affiliation: Princess Margaret Hospital Type of Session: Scientific
The standard of care for women with invasive breast cancer who were treated with lumpectomy is adjuvant radiation therapy and tamoxifen in patients with ER (+) tumors with no contraindications.
This is a study investigating the elimination of radiation therapy and treating patients (>50 years old with T1/2N0 disease) with tamoxifen alone.
The rationale for breast irradiation after lumpectomy is a decreased relapse with modest toxicity.
The rationale for treating patients with tamoxifen alone is that the majority will not relapse and patients can be spared radiation therapy.
760 women were randomized to either tamoxifen 20 mg/d alone or tamoxifen 20 mg/d with adjuvant radiation therapy.
Radiation was given using tangential fields 40 Gy in 16 fractions followed by a boost of 12.5 Gy/5 fractions to the tumor bed.
All were pT1-2, with negative axillary nodes, ER/PR (+) or unknown
Median age was 68 years
636 patients had T1 tumors, 131 had T2 tumors
Median follow up of 34 months
Overall ipsilateral breast relapse rate was 3% (0.3% in the tamoxifen + radiation group and 6% in the tamoxifen alone group, p=.0009)
Overall DFS was 91% (94% in the tamoxifen + radiation group and 89% in the tamoxifen alone group)
There was no difference in distant relapse or OS (94.7% vs 92.8%)
Tamoxifen + radiation results in a significantly lower rate of breast relapse than tamoxifen alone
There was a trend toward a difference in DFS, though by the study's definition, this did not reach statistical significance.
Longer follow-up is needed to determine long term breast control rate after salvage therapy.
A low risk group for breast relapse is yet to be determined.
Clinical/Scientific Implications This study supports the use of routine breast irradiation even in those patients who have a low risk of relapse (i.e.-older patients, ER (+), T1-2N0). These resluts are early, with a low number of events, so the extent of the difference is yet to be seen. However, these results mirror those of the EORTC, which also showed a larger relapse rate in those patients not irradiated.
Oncolink's ASTRO Coverage made possible by an unrestricted Educational Grant from Bristol-Myers Squibb Oncology and Pharmacia Oncology.
May 25, 2010 - In older women with stage I, estrogen receptor-positive, node-negative breast cancer, those who undergo lumpectomy and receive tamoxifen may safely forgo radiation therapy, according to a study released May 20 in advance of the American Society of Clinical Oncology's 46th Annual Meeting, to be held June 4-8 in Chicago.