Do you always need chemotherapy for breast cancer?
Oncologist explains research that informs, personalizes treatment options for women
BY AMBER SMITH
Results of an international study — which includes some Central New York women who are patients at Upstate — are helping oncologists determine which breast cancer patients can skip chemotherapy.
“There is a subset of patients who will benefit from chemotherapy, but the majority of patients might not have to go that route,” explains Upstate oncologist Abi Siva, MD. She‘s referring only to women with hormone-positive breast cancer that has not spread to the lymph nodes. The research does not apply to all women diagnosed with breast cancer.
Women with hormone-positive breast cancer typically have surgery to remove their tumor. Then a sample is sent to a specialized laboratory where the tumor cells are analyzed for specific genetic mutations in a test called Oncotype.
The test predicts the likelihood of recurrence and whether chemotherapy would help.
Women with a low score are considered low-risk and not recommended for chemotherapy. Those with a high score are recommended for chemotherapy. What about those in between?
“It was challenging for physicians to make a decision about chemotherapy for these women because we really didn‘t know what to do until this study came out,” Siva says. “Now we are more confident.
“This is very personalized treatment for each patient, based on her score. We think now we are able to spare about 70 percent of the patients who fall into this category from chemotherapy.”
For the study, led by a cancer researcher at Montefiore Medical Center in New York City, half of the women received chemotherapy and endocrine therapy. The other half received just endocrine therapy. Both groups fared well, with one exception — women under age 50, whose cancer is likely to be more aggressive, were found to derive benefit from chemotherapy.
The study, which began in 2006 and has involved more than 10,000 women, was published in the New England Journal of Medicine and presented at the American Society of Clinical Oncology in Chicago this past spring. Paid for largely by the United States and Canadian governments and philanthropic groups, the research received some funding from Genomic Health, the company that makes the Oncotype tumor test, according to The New York Times.
This is important information because chemotherapy —used to treat a variety of cancers — can take a toll. Side effects can include infections, alterations to kidney and liver function, nausea and vomiting, hair loss and neuropathy, or tingling in the hands and feet. Long-term effects may include difficulty with focused thinking, heart and/or lung problems, muscle weakness, bone and joint problems and secondary cancers or blood disorders.
After surgery to remove the tumor, a woman with hormone-positive breast cancer may face chemotherapy or radiation, both or neither. Regardless, she will receive endocrine therapy, which is designed to suppress the effect of the hormone estrogen.
“Even though we know the surgeon was able to remove the breast tumor, our concern is that there could be microscopic cells left behind in the breast or elsewhere in the body that could come back as a problem, five or 10 years down the road,” Siva explains.
Hormone-positive breast cancers in young women are driven by the ovaries, where estrogen is made. Often these patients receive the medication Tamoxifen, which works by blocking estrogen receptors in breast cancer cells.
In post-menopausal women, cholesterol can be converted into androgens and then estrogens, so doctors often use an aromatase inhibitor medication to block that conversion and decrease the amount of estrogen production.
Siva say studies are underway to determine how many years women should take aromatase inhibitors for the best protection against recurrence.
This article appears in the summer 2018 issue of Cancer Care magazine. Hear a podcast/radio interview with Abi Siva, MD, in which she discusses which breast cancer patient can skip chemotherapy.