Mayo Clinic experts highlight advances in breast cancer research: Decreasing the need for chemotherapy and reducing the intensity of radiation therapy

ROCHESTER, Minn. — Lifesaving cancer therapies can cause serious side effects, both immediately and later in life. "It is essential to continue to study innovative approaches that will eradicate the disease but won't diminish the quality of life for patients diagnosed with cancer," says Roberto Leon-Ferre, M.D., a breast medical oncologist at Mayo Clinic. With breast cancer rates rising among younger people, the need for treatments that provide excellent outcomes with fewer side effects is only increasing.

Mayo Clinic Comprehensive Cancer Center experts highlight breast cancer research that may reduce or eliminate the need for chemotherapy and endocrine treatments and may allow for shorter and less intense radiation therapy courses.

Prognostic Biomarker Identified in Triple-Negative Breast Cancer: Potential to Reduce Chemotherapy Use

Dr. Leon-Ferre's research team recently identified a prognostic biomarker in patients diagnosed with triple-negative breast cancer (TNBC), a type of breast cancer that does not have estrogen or progesterone receptors and that does not have excessive expression of HER2. The researchers found that patients with high levels of naturally existing immune cells called tumor-infiltrating lymphocytes (TILs) within their tumors may have a lower risk of cancer recurrence and better survival rates, even when chemotherapy is not administered.

"This is an important finding because triple-negative breast cancer is a particularly aggressive form of breast cancer that does not respond to hormonal therapies or drugs targeting the HER2 protein," says Dr. Leon-Ferre. "This means treatment options are more limited, often more intense and harsher for patients. However, some patients with TNBC can be cured without chemotherapy, and the key is identifying who those patients are ahead of time." He adds that future research will explore whether TILs can be used to decide who may need and may not need chemotherapy after a TNBC diagnosis.

Study Explores Necessity of Chemotherapy in Premenopausal Women with Intermediate-Risk Breast Cancer

In a separate ongoing trial, Tufia Haddad, M.D., breast medical oncologist at Mayo Clinic, is co-chair of a study comparing two treatment regimens in premenopausal women with intermediate-risk breast cancer: one group with chemotherapy plus ovarian suppression and hormone therapy, and another group without chemotherapy but with ovarian suppression and hormone therapy. The study aims to determine whether chemotherapy's benefits come from its ability to suppress ovarian function (thereby reducing estrogen production) or from its direct cancer-fighting effects. "The results could determine if chemotherapy is necessary or if ovarian suppression and hormone therapy alone are enough in this group of patients, sparing them from the side effects of chemotherapy," says Dr. Haddad.

Endoxifen: A Potent Therapy for Estrogen-Receptor-Positive Breast Cancer Explored by Mayo Clinic

Matthew Goetz, M.D., a breast medical oncologist and director of the Mayo Clinic Breast Cancer Specialized Programs of Research Excellence (SPORE), and the Erivan K. Haub Family Professor of Cancer Research Honoring Richard F. Emslander, M.D., has spent more than a decade studying the use of endoxifen for the treatment of patients with estrogen-receptor-positive breast cancer (ER-positive breast cancer or ER+), the most common subtype of breast cancer.

Endoxifen, the most potent byproduct of tamoxifen, stops the growth of estrogen-dependent cancer cells and blocks protein kinase C, which may contribute to the aggressiveness of some cancers. Premenopausal patients with ER+ breast cancer are treated with ovarian function suppression and aromatase inhibitors to lower estrogen levels and slow cancer growth. While effective, this regimen causes significant side effects from deep estrogen suppression. Dr. Goetz's SPORE-funded study explores whether endoxifen alone can eradicate cancer cells, potentially eliminating the need for more toxic treatments like chemotherapy. He is also studying the role of protein kinase C in ER+ breast cancer.

Mayo Clinic Study Finds Shortened and Less Intense Radiation Therapy Effective for Breast Cancer Patients

Radiation therapy can be an essential part of a person's breast cancer treatment plan; however, it can lead to changes in the appearance of the skin, swelling, pain and other complications. These side effects can be detrimental to a patient's quality of life. In a recent study, Mayo Clinic breast cancer researchers found they can safely reduce the intensity and shorten the course of radiation treatment to three days for select patients with breast cancer following their lumpectomy.

"Normally, this treatment takes five to 15 days and can sometimes cause unwanted side effects, including changes in how the breast looks. However, this new method administers a lower dose of radiation over just three sessions using either photons, protons or brachytherapy," says Robert Mutter, M.D., a Mayo Clinic radiation oncologist and lead author of the study. "The new personalized approach was well-tolerated by the patients and resulted in excellent cancer control with better long-term aesthetic results compared to what has previously been reported with longer treatments."

Collectively, this research is leading to innovative approaches and helping clinicians and patients make informed treatment decisions, potentially sparing patients from some of the more severe side effects of chemotherapy, endocrine therapy and radiation.

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About Mayo Clinic Comprehensive Cancer Center 
Designated as a comprehensive cancer center by the National Cancer Institute, Mayo Clinic Comprehensive Cancer Center is defining the cancer center of the future, focused on delivering the world's most exceptional patient-centered cancer care for everyone. At Mayo Clinic Comprehensive Cancer Center, a culture of innovation and collaboration is driving research breakthroughs in cancer detection, prevention and treatment to change lives.