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HealthDay reporters
FRIDAY, Dec. 3, 2021 (HealthDay News) – A genetic test could identify older breast cancer patients who may refuse chemotherapy after surgery, even if the cancer has spread to nearby lymph nodes. clinical trial.
“For decades, women with breast cancer that has spread to the axillary area [armpit] lymph nodes were treated with chemotherapy after surgery to reduce the risk of recurrence, “said Dr. Francisco Estreva, head of medical breast oncology at Lenox Hill Hospital in New York.
However, the findings show that postoperative chemotherapy may not be necessary for all patients, so the study “represents a paradigm shift in medical oncology,” said Estreva, who was not involved in the new study.
The study was led by Dr. Kevin Kalinski, a SWOG researcher and medical breast oncologist at the Winship Cancer Institute at Emory University in Atlanta. SWOG is a group of clinical cancer trials funded by the US National Cancer Institute. The findings were published on December 1 in New England Medical Journal.
The study was conducted at 632 sites in nine countries and included more than 5,000 women with HR +, HER2- breast cancer, which has spread to as many as three lymph nodes.
HR + means that the breast tumor contains hormone receptors (HR) that make it sensitive to hormones such as estrogen. Most breast cancers are HR +. HER2 is short for “human epidermal growth factor receptor 2”, which plays a role in how quickly breast cancer cells multiply. Tumors that are negative for HER2 are considered less aggressive than HER2 + tumors.
According to the study’s authors, in about one-third of HR + patients with HER2 breast cancer, the cancer had already spread to their lymph nodes at the time of diagnosis. These women have a higher risk of cancer recurrence after treatment.
But do they all need chemotherapy? To help understand, the HR + / HER2 tumors of the women in the study were tested for the expression of 21 genes in tumor tissue to assess their risk of recurrence of breast cancer. The test used is called the Oncotype DX multigene test.
All women had a gene (RS) repeat score of 25 or lower on a scale of 0-100, indicating a low or intermediate risk of recurrence, Kalinski’s team found.
After cancer surgery, half of the women receive chemotherapy followed by endocrine (hormone) therapy, while the other half receive only endocrine therapy.
Five years after treatment, there were no clinically significant or statistically significant differences between the two groups in terms of the incidence of recurrence of breast cancer or new invasive primary cancer.
However, there was a clear difference when they focused only on younger premenopausal women, who accounted for about a third of patients. In this group of women, those who received chemotherapy plus endocrine therapy had a 40% higher chance of developing new primary cancer than those who received endocrine therapy alone.
In contrast, chemotherapy does not provide additional benefits for postmenopausal women, according to the study.
In premenopausal patients, the five-year recurrence rate was 89% for women who received endocrine therapy alone, compared with 93.9% for those who received chemotherapy and endocrine therapy. In postmenopausal patients, the five-year recurrence rate is 91.9% versus 91.3%, a difference that is not statistically significant, Kalinski’s group said.
“These are clinically significant and impactful data,” Kalinski told SWOG.
The finding that postmenopausal women with a certain prevalence of lymph node cancer and a low gene-based risk score may miss postoperative chemotherapy is good news, he added.
“This will save tens of thousands of women the time, cost and potentially harmful side effects that can be associated with chemotherapy,” Kalinski said.
On the other hand, premenopausal patients with lymph node involvement and low-risk outcomes “are likely to benefit from chemotherapy,” he said.
Estreva agreed.
“Based on the results of this study, a significant number of postmenopausal women with hormone-positive breast cancer and lymph node involvement [up to 3 positive lymph nodes] “Chemotherapy can be spared with the Oncotype DX multigenic test,” he said. specific therapies in individual patients. “
The results of further analysis of the study will also be presented at the Breast Cancer Symposium in San Antonio in 2021 on December 8.
More info
The National Cancer Institute of the United States has more information on breast cancer.
SOURCES: Francisco Estreva, MD, Chief, Medical Breast Oncology, Lenox Hill Hospital, New York; SWOG, press release, 1 December 2021
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