Radiation Therapy Benefits All Early-Stage Hormone-Receptor-Positive Breast Cancer

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The risk of recurrence (the cancer coming back) was lower when early-stage hormone-receptor-positive, HER2-negative breast cancer at low risk of recurrence was treated with radiation and hormonal therapy after surgery, compared to treatment with hormonal therapy alone, according to a study.

The research was presented on April 28, 2019, at the European Society for Radiotherapy and Oncology (ESTRO) Congress in Milan, Italy. Read the abstract of "Antihormones with or without irradiation in breast cancer: 10-year results of the ABCSG 8A trial."

Doctors call treatments given after breast cancer surgery adjuvant treatments.

Doctors want to make sure women diagnosed with breast cancer receive only the treatment they need and are not overtreated. So, researchers wanted to know if there were any groups of women who might not benefit from radiation therapy after lumpectomy to remove early-stage hormone-receptor-positive, HER2-negative disease.

How the study was done

The study was done by the Austrian Breast and Colorectal Cancer Study Group and included 869 postmenopausal women diagnosed with early-stage hormone-receptor-positive, HER2-negative breast cancer between 1996 and 2004. All the cancers were considered to have a low risk of recurrence, meaning they were grade 1 or grade 2, were smaller than 3 centimeters (cm), and there was no cancer in the lymph nodes.

All the women had lumpectomy to remove the cancer. After surgery, the women were randomly assigned to receive either:

  • hormonal therapy alone
  • hormonal therapy and whole breast radiation

Whole-breast radiation therapy is usually given as one treatment per day, 5 days a week, for 5 to 7 weeks. A Gray (Gy) is the unit radiation oncologists use to measure the dose of radiation. In this study, all the women received a total dose of 50 Gy, likely over 5 weeks (2 Gy at each treatment). Additionally, 71% of the women received a supplemental “boost” dose of 10 Gy that targeted the area where the cancer was at the end of the treatment regimen.

Half the women were followed for more than 10 years, and half were followed for shorter periods of time.

During follow-up:

  • 10 women treated with hormonal therapy and whole-breast radiation had a breast cancer recurrence
  • 31 women treated only with hormonal therapy had a breast cancer recurrence

Disease-free survival rates were:

  • 94.5% for women treated with hormonal therapy and whole-breast radiation
  • 88.4% for women treated with hormonal therapy alone

Disease-free survival is how long the women lived without a recurrence.

The researchers calculated that whole-breast radiation was linked to a 73% reduction in the risk of recurrence. This difference was statistically significant, which means that it was likely due to the difference in treatment and not just because of chance.

"We believe that the additional benefits of postoperative radiotherapy have been confirmed in hormone receptor positive patients, regardless of whether or not they are at high risk of breast cancer recurrence," lead author Gerd Fastner, M.D., of Paracelsus Medical University in Salzburg, Austria, said in a statement. "Our findings show that radiotherapy is still highly effective in significantly improving local control and disease-free survival in combination with anti-hormones, compared to anti-hormones alone. This remains true after long-term follow-up of breast cancer patients with a good prognosis. In our analysis the omission of whole breast irradiation turned out to be the main predictor for in-breast recurrences."

Fastner added that only frail, elderly women who would not be able to tolerate radiation therapy should consider skipping the treatment.

What this means for you

The results of this study support current North American standard-of-care treatment guidelines after lumpectomy for early-stage hormone-receptor-positive, HER2-negative breast cancer.

If you’ve been diagnosed with early-stage hormone-receptor-positive, HER2-negative breast cancer and are deciding on treatments after lumpectomy, it’s likely that your doctor will recommend hormonal therapy and radiation therapy. If your doctor recommends hormonal therapy alone, you may want to ask why and talk about the results of this study.

Together, you and your doctor will figure out the best treatment plan for you and your unique situation.

For more information on radiation therapy and how it is given, visit the Breastcancer.org Radiation Therapy pages.

To talk with others about radiation therapy, join the Breastcancer.org Discussion Board forum Radiation Therapy - Before, During, and After.

Written by: Jamie DePolo, senior editor


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