The Role of Radiotherpay and Tamoxifen in the Management of Node Negative Invasive Breast Cancer </= 1.0 cm Treated with Lumpectomy: Preliminary Results of NSABP Protocol B-21

James Metz, MD
OncoLink Associate Editor
Last Modified: May 21, 2000

Presenter: N. Wolmark
Affiliation: NSABP

Although definitive radiation therapy after lumpectomy has been standard of care for breast conservation for breast cancer, there has been some debate if radiation therapy is needed for small tumors (< 1.0cm) when the patient is treated with Tamoxifen. This study was performed to determine if Tamoxifen alone is as effective as radiation therapy is preventing recurrences in the breast. Also, this study was designed to evaluate whether the addition of Tamoxifen to radiation therapy is superior to either treatment alone after lumpectomy.

Materials and Methods:

  • From 6/89 - 12/98 1,009 patients were entered into this prospective trial. All women had lymphnode negative breast cancer with a small < / = 1.0 cm treated with lumpectomy and axillary lymphnode dissection.
  • Patients were then randomized to:
    • Arm 1 - Tamoxifen alone (5 years)
    • Arm 2 - Radiation therapy + placebo
    • Arm 3 - Radiation therapy + Tamoxifen
  • The median follow-up time was 68.3 months.
  • 5-year survival was 97% in all 3 arms.
  • Risk of ipsilateral breast recurrence was:
    Arm 1 - Tam alone 10.7% } p = .01
    Arm 2 - XRT 4.8% } p = .007
    Arm 3 - XRT + Tam 2.0%
  • Cumulative incidence of contralateral breast tumors was reduced by Tamoxifen from 3.0% to 0.6%
Authors' Conclusions
  • Tamoxifen cannot replace radiation therapy in the management of even this very favorable subset of patients for the reduction of ipsilateral breast recurrences.
  • Combination of Tamoxifen and radiation is superior to radiation therapy alone for the reduction of ipsilateral breast recurrences.
  • Tamoxifen reduces the incidence of contralateral breast cancer in this group.
Clinical/Scientific Implications:
  • This study continues the long tradition of the NSABP in completing influential trials that effect breast cancer treatment.
  • When this study is evaluated in combination with the other NSABP trials, one can conclude the following:
    • There is no subset of patients treated with breast conserving therapy that does not benefit from the addition of radiation therapy to reduce ipsilateral breast recurrencies.
    • Although Tamoxifen cannot replace radiation therapy, the combination of radiation and Tamoxifen improves the local control of radiation alone.
    • Tamoxifen reduces the chance of developing a contralateral breast cancer.