Can Certain Younger Post-Menopausal Women With Low-Risk Breast Cancer Skip Radiation?

Post-menopausal women aged 50 to 59 diagnosed with stage I, hormone receptor-positive, HER2-negative breast cancer with an Onctoype DX Breast Recurrence Score of 18 or lower who take hormonal therapy after lumpectomy may be able to skip radiation after surgery, according to a study. Still, you and your doctor need to consider several factors when making decisions about treatment after surgery.

The research was presented on Dec. 7, 2023, at the San Antonio Breast Cancer Symposium (SABCS) and published simultaneously in the Journal of Clinical Oncology. Read:

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  the SABCS media release and abstract of “Five-year outcomes of the IDEA trial of endocrine therapy without radiotherapy after breast-conserving surgery for post-menopausal patients age 50-69 with genomically-selected favorable Stage I breast cancer”

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  the Journal of Clinical Oncology abstract of “Omission Of Radiotherapy After Breast Conserving Surgery For Women With Breast Cancer With Low Clinical and Genomic Risk: 5-Year Outcomes of IDEA.”

People diagnosed with early-stage, hormone receptor-positive breast cancer are commonly prescribed radiation therapy and hormonal therapy after lumpectomy to reduce the risk of recurrence (the cancer coming back).

Research shows that lumpectomy plus radiation offers the same outcomes as mastectomy. Still, radiation therapy may be inconvenient for some people because it usually involves daily trips to the treatment center for three to seven weeks. Radiation therapy also can cause side effects.

Hormonal therapy also can cause side effects. Research has shown that about 25% of women who are prescribed hormonal therapy to reduce the risk of recurrence either don’t start the medicine or stop taking it early because of troubling side effects.

Doctors are always looking for ways to effectively treat breast cancer with as few treatments as possible.

Results from the LUMINA study, published in August 2023, suggested that certain older post-menopausal women diagnosed with early-stage, hormone receptor-positive, HER2-negative breast cancer with a very low risk of recurrence could take hormonal therapy alone after lumpectomy and skip radiation therapy. 

The researchers did this study for two reasons:

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  to see if certain younger post-menopausal women diagnosed with the same type of breast cancer as the older women in the LUMINA study could take hormonal therapy alone after lumpectomy

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  to see if using the Oncotype DX Breast Recurrence Score would be a good way to identify these women

Called IDEA (Individualized Decisions for Endocrine therapy Alone), the study included 200 post-menopausal women diagnosed with stage I, hormone receptor-positive, HER2-negative breast cancer:

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  60 women were aged 50 to 59

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  140 women were aged 60 to 69

The women joined the study between June 2015 and October 2018.

All the women had Onctoype DX Breast Recurrence Score testing and had a Recurrence Score of 18 or lower, which means the cancer has a low risk of coming back (recurring).

All the women took at least five years of hormonal therapy after lumpectomy to remove the cancer.

This analysis included information from 186 women after five years of follow up. The other 14 women had been followed for less than 56 months, so weren’t included in the analysis.

At five years, 184 women were alive and only two women had a breast cancer recurrence.

Of the two women that died, one left the study and the researchers couldn’t determine her cause of death. The other woman died from something other than breast cancer.

Of the two women who had a recurrence:

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  one recurrence was in the lymph nodes on the same side as the original breast cancer about two years after diagnosis

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  the other was a new breast cancer in the same breast 49 months after initial diagnosis

The researchers plan to follow the women for a total of 10 years.

It’s important to know that estrogen receptor-positive breast cancer has a higher risk of recurring more than 10 years after diagnosis than hormone receptor-negative breast cancer.

“These findings indicate that younger post-menopausal patients with stage I breast cancer who skip radiotherapy after breast-conserving surgery have a very low risk of disease recurrence within five years,” said lead author Reshma Jagsi, MD, DPhil, during a media briefing on the study. “However, five years of follow-up is an early time point for this population, and longer-term follow-up of this study and others will be essential to determine whether this option can be safely offered to women in this age group.

“We also have to recognize that advances in radiation therapy have substantially reduced both the burdens of side effects and time, since this trial was started,” Dr. Jagsi added. “This has implications for the risk-benefit ratio of receiving radiation. I would encourage any women who meet the criteria for IDEA to consider enrolling in the NRG BR007: Evaluating De-escalation of Breast Radiation (DeBRa) trial, which is a randomized study comparing two groups: one that gets radiation and anti-estrogen therapy and one that gets anti-estrogen therapy alone. On-going research is essential to helping us determine if the option of skipping radiation therapy can be offered to a broader group of women than current guidelines recommend.”

If you’re a younger post-menopausal woman diagnosed with stage I, hormone receptor-positive, HER2-negative breast cancer with a very low risk of recurrence and are deciding on treatments after surgery, this study offers some encouraging results.

Still, it’s important to remember that this study was what’s called a single-arm study. There was no group of women who received radiation, so we don’t know if they would have better outcomes than the women who didn’t receive radiation.

It’s also important to remember that these  results come after only five years of follow-up. Dr. Jagsi was very emphatic that longer follow-up and randomized studies are needed before treatment standards change.