Preliminary Results of a Randomized Study of Tamoxifen Alone or Tamoxifen and Breast Radiation in Women over 50 Years of Age with T1/2 N0 Disease

Ryan Smith, MD
University of Pennsylvania Cancer Center
Last Modified: November 6, 2001

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Presenter: A. Fyles
Presenter's Affiliation: Princess Margaret Hospital
Type of Session: Scientific

Background

  • 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.

    Materials and Methods

  • 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

    Results

  • 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%)

    Author's Conclusions

  • 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.

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