Genetic test could help some breast cancer patients avoid radiation after lumpectomy

By Denise Mann Health Day Reporter

FRIDAY, Dec. 9, 2022 (HealthDay News) — A new genetic test could help determine which people with breast cancer can safely skip radiation after breast-conserving surgery to remove their tumor.

People with invasive breast cancer who had low scores on an experimental gene panel were just as likely to experience a recurrence whether or not they received radiation therapy after breast-conserving surgery, Swedish researchers report.

As it stands, people with this type of breast cancer usually have surgery to remove the cancer, followed by radiation therapy, to reduce the risk of their breast cancer coming back in the same place.

“For the first time, a genetic screening test can predict which patients may miss radiation,” said study author Dr. Per Karlsson. He is Professor of Oncology at the Sahlgrenska Comprehensive Cancer Center and at the University of Gothenburg in Sweden.

More research is needed before this genetic test is ready for prime time, Karlsson said.

“We’ll confirm the results in new cohorts, and we’ll also start prospective trials to be sure this is correct, but it looks really promising,” he added.

For the study, researchers assessed the predictive power of POLAR (Profile for the Omission of Local Adjuvant Radiotherapy), a 16-gene panel that was developed based on differences between people with and without local recurrence after surgery. conservative breast.

The study included 623 people from three trials whose cancer had not spread to their lymph nodes. Their breast cancers were also estrogen receptor positive and HER2 negative. Their tumors were analyzed after surgery to see which genes were expressed.

Each person received a POLAR score based on this analysis, and then researchers looked at the benefits of radiation therapy in people with high and low scores.

The main finding? People with a high POLAR score may benefit from radiation therapy, while those with lower scores may likely skip it, according to the study results.

People with high POLAR scores who received radiation therapy after breast-conserving surgery had a 63% lower risk of local recurrence than those who did not receive radiation therapy. In contrast, there was no difference in the recurrence rates seen in people with low POLAR scores, whether or not they received radiation. After 10 years, 5% of people with low scores who received radiation had a local recurrence, compared to 7% of those who did not, investigators found.

It’s a win any time a person can avoid radiation without risking cancer recurrence, Karlsson said. “There are side effects for a small percentage of people, and if in the future we can omit radiation for some patients, that will be good for quality of life,” he noted.

In addition to being time consuming, radiation can cause fatigue as well as skin side effects such as rashes, pain, redness and swelling.

The results were to be presented Friday at the breast cancer symposium in San Antonio. Research presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.

Breast cancer experts who reviewed the new study agreed that doctors are entering a new era in the diagnosis and treatment of breast cancer.

This type of genetic profiling of breast tumors is the future, said Dr. Julia Smith, a medical oncologist at NYU Langone Perlmutter Cancer Center in New York. “We try to minimize the number of treatments we give to certain subgroups based on the molecular and genetic profiles of their cancer.”

This study helps define a subgroup of people who may not need radiation, she said.

“People with this type of breast cancer tend to do well initially,” Smith noted. “We need a larger group of women who we can follow for longer because people with these types of breast cancer usually don’t recur until 10 to 15 years later.”

Doctors don’t want to overtreat people, agreed Dr. Katherina Zabicki Calvillo, breast surgeon and founder of New England Breast and Wellness in Wellesley, Mass. ” she says.

“It may be safe to omit radiation in certain populations. Although well tolerated, radiation still has adverse side effects and affects quality of life and return to work,” Calvillo explained. There may also be cost savings, she noted.

Calling the new study “interesting and important”, Dr Marisa Weiss said the results can help tailor treatment recommendations regarding radiation therapy. She is the chief medical officer and founder of Breastcancer.org in Ardmore, PA.

“The POLAR 16-gene genomic test shows great promise in Swedish women,” Weiss said. “It will be important to test its validity in the much more heterogeneous population of the United States before it can be applied to diverse populations with confidence.”

SOURCES: Per Karlsson, MD, professor of oncology, Sahlgrenska Comprehensive Cancer Center, University of Gothenburg, Sweden; Julia Smith, MD, medical oncologist, NYU Langone Perlmutter Cancer Center, New York; Katherina Zabicki Calvillo, MD, Founder, New England Breast and Wellness, Wellesley, Mass.; Marisa Weiss, MD, Chief Medical Officer, Founder of Breastcancer.org, Ardmore, PA; presentation, San Antonio Breast Cancer Symposium, December 9, 2022

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