As you know, the go-to method of treatment is often chemotherapy—the use of strong drugs to target and kill cancer cells. It’s a taxing treatment, with side effects like nausea, hair loss, and a score of other symptoms.
Let’s backtrack a bit: Chemotherapy is a course of action that’s only taken when absolutely necessary. But it’s not always easy for doctors to make that judgment call. They’ll usually conduct a test—known as Oncotype DX—that analyzes 21 genes and assigns a “recurrence score” between 0 and 100: The higher the number, the more likely the cancer is to recur. Women who score under 10 typically aren’t treated with chemo following surgery or radiation therapy, and women who score over 25 are.
However, majority of women score between 11 and 25, which makes it tough for doctors to decide on a method of treatment. Consequently, many women may be put through chemo when they’d be able to safely recover without it.
The study involved 10,273 women who were in the early stages of breast cancer—specifically, hormone-receptor-positive, HER2-negative breast cancer, which makes up about half of all breast cancer cases in the U.S.
Of the 9,719 eligible women with follow-up information, 69 percent scored between 11 and 25. Then, they were separated into two groups. One of the groups was treated with endocrine therapy, which lowers the chance of recurrence by stopping the hormones estrogen and progesterone from boosting cancer cell growth. The other group was treated with both chemotherapy and endocrine therapy.
The treatments were found to be equally effective, and researchers determined that women over 50 with hormone-receptor-positive, HER2-negative breast cancer especially could safely forego chemo. Women 50 or under who scored 15 or below could also safely skip chemo. But those with a score of 16-25 benefitted from chemo; the treatment was necessary. Those findings translate to some pretty big numbers in the U.S. alone.
“This is a major finding,” Larry Norton, M.D., a medical oncologist at Memorial Sloan Kettering Cancer Center in New York, told Reuters. “It means that maybe 100,000 women in the United States alone do not require chemotherapy.”
They key factor in the study is women’s recurrence score, meaning that to figure out how best to treat each individual’s case, women need to undergo a gene test such as Oncotype DX. For more on gene testing and breast cancer, check outbreastcancer.org.
