It may be possible for some postmenopausal women to avoid some breast cancer treatment without compromising survival, according to two new studies presented at the San Antonio Breast Cancer Symposium (SABCS), hosted by UT Health San Antonio, the American Association for Cancer Research, and the Dan L. Duncan Comprehensive Cancer Center at Baylor College of Medicine.
The meeting was held virtually December 8 to 11.
One study found that postmenopausal women with early-stage breast cancer who were at low risk of recurrence can skip chemotherapy after surgery. The other found that older patients may be able to skip radiation therapy following breast-conserving surgery.
The studies reflect a resolve in the oncology field to avoid overtreatment of disease, sparing patients from some of the side effects that can accompany treatments like chemotherapy and radiation.
“We’re looking to move beyond a one-size-fits-all approach,” said the presenting author of the first study, Kevin Kalinsky, MD, director of the Glenn Family Breast Center at Winship Cancer Institute of Emory University. “This is another step forward in trying to achieve precision medicine.”
Dr. Kalinsky’s study followed women with hormone receptor-positive (HR positive), HER2-negative breast cancer — the most common form of breast cancer — for about five years following treatment.
The 5,083 study participants had early-stage lymph node-positive cancer (meaning the cancer had spread to one to three lymph nodes) and a recurrence “score” of 25 or lower.
Breast cancer recurrence scores are based on the presence of 16 cancer-related genes and can range from 0 to 100.
All the study participants received endocrine therapy following surgery, while about half were randomly assigned to receive chemotherapy as well.
The study, which was organized by the SWOG Cancer Research Network and is called RxPONDER, found that while additional chemotherapy improved disease-free survival rates by about 5 percent for premenopausal women, postmenopausal patients gained no added benefit.
“This will save tens of thousands of women the time, expense, and potentially harmful side effects that can be associated with chemo infusions,” Kalinsky said.
Questions remain about whether chemotherapy has different biological effects based on menopausal status, or simply exerts its effect by shutting down ovarian function.
In the second study, known as PRIME II, researchers found that older patients with HR-positive breast cancer may be able to skip radiation treatment after breast-conserving surgery.
The study enrolled 1,326 women ages 65 and older who had HR-positive breast cancer that had not spread. All of the women had breast-conserving surgery and received hormone therapy. Half of the study participants were assigned to also receive radiation therapy after surgery.
Previous research has suggested a higher risk of cancer recurrence among patients who do not receive radiation therapy. However, the new study found no significant differences in survival, metastasis (disease spread), or new breast cancers among the two groups after five years of follow-up.
The study is important because many postmenopausal women are diagnosed with less-aggressive breast cancers but still receive whole-breast radiation therapy following breast-conserving surgery.
“Over half the patients diagnosed with breast cancer in developed countries are over the age of 65 years,” said Ian Kunkler, MBBCh, a professor of clinical oncology at the Western General Hospital at the University of Edinburgh in Scotland. “We were interested in determining whether older patients with low-risk breast cancer could be spared radiation therapy.”
“We found that omitting postoperative radiation therapy did not compromise survival or increase the risk of distant metastasis,” Dr. Kunkler said. “Based on these results, we believe that omission of radiation therapy after breast-conserving surgery should be an option for older patients with localized, HR-positive breast cancer who are receiving adjuvant hormone therapy and meet certain clinico-pathological criteria.”
The study findings may not be applicable to patients with high-grade tumors or tumors larger than 3 centimeters, he said, because there were only a few patients with grade-three tumors in the study.
In Other News From SABCS
Verzenio Benefits Women With High-Risk, Early-Stage Breast Cancer
A fresh analysis of the landmark phase 3 monarchE clinical trial showed adding Verzenio (abemaciclib) to endocrine therapy significantly benefits patients with high-risk, lymph-node positive, early-stage breast cancer that’s classified as HR-positive, HER2-negative.
Many patients with HR-positive, HER2-negative early-stage disease will not experience a recurrence of cancer with endocrine therapy alone, said the study presenter, Priya Rastogi, MD, associate professor in the department of medicine at the University of Pittsburgh and medical director of the National Surgical Adjuvant Breast and Bowel Project (NSABP) Foundation.
But about 20 percent of patients will experience a recurrence of the disease within 10 years of their initial diagnosis. These recurrences are typically diagnosed as incurable metastatic breast cancer, she said.
An earlier release of data from the trial, which includes 5,637 patients, showed the addition of Verzenio to endocrine therapy curbed the risk of invasive disease recurrent by about 25 percent. The new data, which followed patients for longer, showed that those who received Verzenio experienced a 28.7 percent reduced risk of invasive disease.
Since some women experience relapse several years after their initial treatment, it will be important to gather long-term data on the treatment regimen, said SABCS codirector C. Kent Osborne, MD, professor in the department of medicine, hematology, and oncology at Baylor College of Medicine in Houston. Dr. Osborne was not involved in the study.
The study will continue with a longer-term assessment of overall survival rates among the two groups.
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Radiation-Related Side Effects May Be Overlooked
Women with breast cancer who undergo radiation therapy may have side effects that go unreported or unnoticed by healthcare providers, according to a study from the University of Michigan.
The study was comprised of 9,868 patients with breast cancer who were treated with radiation therapy. Researchers compared the patients’ reports of side effects with those assessed by their physicians.
The study showed physicians tended to under-recognize pain severity as well as itching (pruritus), swelling, and fatigue. Among the 5,510 patients who reported at least one substantial symptom during radiation therapy, 53.2 percent had under-recognition of at least one of the four symptoms.
“Recognition of symptoms is necessary for appropriate supportive care,” said Reshma Jagsi, MD, DPhil, the Newman Family Professor and deputy chair of the department of radiation oncology and director of the Center for Bioethics and Social Sciences in Medicine at the University of Michigan in Ann Arbor.
“This work reveals that [physicians] systematically miss substantial symptoms in certain patients, including patients who are younger or of Black or other race.”
The study points to the need for physicians to improve the way they assess side effects in patients, said SABCS codirector Virginia Kaklamani, MD, a professor of medicine in the division of hematology and medical oncology, University of Texas Health Sciences Center in San Antonio. Dr. Kaklamani was not involved in the study.
“It’s really quite surprising to me that in 30 percent of cases there was under-recognition compared to what patients are reporting,” she said. “We need to do a better job.”
“I think the key here is improving physician-patient communication,” she said. “That involves a spectrum of potential interventions which begins with addressing our own unintentional biases.”
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