Preliminary Results Of A Randomized Study Of Tamoxifen +/- Breast Radiation In T1/2 N0 Disease In Women Over 50 Years Of Age

Diana Stripp, MD

University of Pennsylvania Cancer
Last Modified: May 15, 2001

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Presenter: Anthony Fyles
Affiliation: Princess Margaret Hospital, Toronto, ON, Canada

Background:

    1. Breast radiation (RT) shows definitive reduction in local relapses, however, with moderal toxicity and without a survival benefit.
    2. In Tamoxifen (TAM) treated pts, majority have no relpase without RT. With RT, TAM further decreased rate of relapse as compared to pts treated with RT alone.
    3. Salvage for breast conservation therapy (BCT) is overall effective.
    4. This study was designed to determine whether tamoxifen (Tam) resulted in similar disease-free survival (DFS) as Tam and breast radiation (RT) in women over 50 with T1 and T2 node negative breast cancer. Secondary endpoints included ipsilateral breast tumour relapse (IBTR) and overall survival (OS).

Materials and Methods:

    1. 769 women were randomized to Tam 20 mg daily for 5 years or Tam + RT.
    2. Median age was 68 years, 638 patients had pT1 lesions and 131 pT2 tumors. 634 pts had pathologically negative nodes and 135 over age 65 were clinically node negative. 699 pts were estrogen receptor (ER) +.
    3. Median follow-up was 3.4 years and patient and tumour characteristics were well balanced between the two arms. A planned interim analysis was performed in particular to assess patterns of relapse.

Results:

    1. Overall, there were 36 relapses from breast cancer in the Tam arm and 19 in the Tam + RT arm.
    2. IBTR was seen in 22/384 (5.7%) patients in the Tam arm compared to 2/385 (0.5%) in the Tam + RT group.
    3. At 4 years, the ipsilateral breast relapse- free rate was 94% for Tam and 99.7% for Tam + RT (p=0.0009).
    4. There was no difference in relapse at regional or distant sites, nor in the contralateral breast.
    5. No difference was seen in the number of deaths due to breast cancer (8 and 9 for Tam + RT and Tam, respectively), nor in OS (94.7% and 92.8% at 4 years).

Authors' Conclusions

    1. Tamoxifen and breast RT results in a significantly lower rate of breast relapse than Tam alone in women over 50 with node-negative breast cancer.
    2. No significant different in disease free survival between the 2 arms.
    3. Further follow-up will determine the long- term breast control rate following salvage therapy.

Clinical/Scientific Implications:

    1. Combination of Tam + RT decreased the IBTR rate compared with Tam alone, however, it did not show an advantage in DFS or OS. In pts with co- morbidity, or in places where acess to a RT facility is limited, treating this group of pts with Tam without RT may be reasonable alternative.
    2. Preferences of the treatment will eventually be an individual issue as salvage therapies could be either mastectomy or repeat lumpectomy with RT in women treated with Tam alone.

ASCO Abstract 92

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