When Do You Need Chemo for Early-Stage Breast Cancer?
One of the first questions that many people have when planning their treatment for early-stage breast cancer is: Will I need chemo? Although experiences with chemo side effects vary a lot, many people would prefer to just avoid chemo if they can. Advances in cancer research and treatment are making that more of a possibility.
Chemo is still an effective, necessary treatment for some breast cancers. But treatment guidelines have changed so that chemo isn’t recommended for as many people as it was 20 years ago. Today, tests that are done on the tumor tissue — especially genomic tests such as Oncotype DX — can help some people determine their individual risk of the cancer returning after surgery and whether chemo would be beneficial in lowering that risk.
Chemo is still recommended for certain invasive breast cancers that are stage I, II, III, or IV and have a high risk of recurring or spreading. It isn’t used for stage 0 (non-invasive) breast cancers.
Why is chemo recommended for some breast cancers?
Chemo medicines work by killing breast cancer cells or stopping them from multiplying. When given after surgery, chemo can destroy microscopic breast cancer cells that weren’t visible to the surgeon and may be remaining in the body. This is how chemo can lower the chances of the cancer coming back. (Chemo is also sometimes given before surgery to shrink a larger tumor or to see how the tumor responds to particular chemo medicines and help determine which treatments would be needed after the surgery.)
Read more of our special series to learn about chemo side effects, ways to reduce them, and how to talk with your treatment team about chemo dosing options.
Chemo side effects are often worse than those of other medicines because chemo damages not only rapidly dividing cancer cells but fast-growing, healthy cells throughout the body, as well.
“The reason chemo has stuck around so long is that we know it works,” says Evanthia Roussos Torres, MD, PhD, a medical oncologist and researcher at the Keck School of Medicine of USC, in Los Angeles. “We want to replace it with treatments that work as well but are less toxic. But for now, it’s still the standard of care for some patients.”
Some people whose doctors recommend chemo may consider turning it down because they would prefer more natural or less toxic treatment approaches. However, says Sameer Gupta, MD, MPH, a medical oncologist at Bryn Mawr Hospital in Bryn Mawr, PA, it’s important that they fully understand the risks of skipping chemo in their individual situation.
“Once you’ve made the decision, you can’t go back in time and change it,” he says. “For some people, not choosing chemo may increase the chance of the cancer coming back.”
Which early-stage breast cancers may not need chemo?
Many people diagnosed with early-stage (stage I, stage II, or stage IIIa) invasive, hormone receptor-positive, HER2-negative breast cancer can safely skip chemotherapy after surgery if their test results:
show they have a relatively low risk of recurrence and
suggest that chemo is likely to not be beneficial
In most cases, their oncologist will recommend that they still take hormonal therapy for five to 10 years after surgery to reduce their recurrence risk.
Which early-stage breast cancers usually do need chemo?
Oncologists are more likely to recommend adding chemotherapy to the treatment plan of a person with early-stage breast cancer if:
the cancer has characteristics that make it more aggressive, such as being hormone receptor-negative, triple-negative, or HER2-positive (in many of these cases, chemo before surgery may be recommended)
the person is assigned female at birth and has not gone through menopause (since breast cancer is often more aggressive in these cases)
the cancer is of a larger size, making surgery difficult (in which case, chemo before surgery may be recommended)
If there are cancer cells in the lymph nodes near the affected breast, that also increases the likelihood that chemo would be recommended, particularly in people who are younger than age 35.
However, some people with early-stage, hormone receptor-positive, HER2-negative breast cancer, who have cancer cells in the lymph nodes near the affected breast, may have the option of taking the targeted therapy Verzenio (chemical name abemaciclib) and hormonal therapy instead of receiving chemotherapy.
How has breast cancer treatment evolved?
It used to be that breast cancer treatment decisions were mainly based on the stage of the cancer — its size and whether and how much it had spread in the body. This started to change during the 1970s and 1980s, as researchers learned that not all breast cancers behave the same way. For example, certain breast cancers are fueled by the hormones estrogen and/or progesterone and/or by the protein HER2. And triple-negative breast cancer isn’t fueled by any of those substances. These different types of breast cancers are known as subtypes.
A better understanding of breast cancer subtypes has allowed treatment to become much more tailored to a person’s diagnosis. It has led to the development of the biomarker tests that are now routinely done on breast tumors (to identify hormone receptor status, HER2 status, and other tumor characteristics). It has also led to many new treatments, such as hormonal therapies to treat hormone receptor-positive breast cancer and Herceptin (chemical name: trastuzumab) and Perjeta (chemical name: pertuzumab) to treat HER2-positive breast cancer.
In 2004, genomic tests started to become a standard part of care for people diagnosed with early-stage, estrogen receptor-positive, HER2-negative breast cancer. The tests can provide even more information about the benefits of adding chemo to an individual’s treatment plan.
“[Genomic testing] probably cut the use of chemo in half among people with stage I and stage II breast cancer,” says Debu Tripathy, MD, professor of medicine and chairperson of the Department of Breast Medical Oncology at the University of Texas MD Anderson Cancer Center in Houston, TX. “Before we had gene expression profiling [genomic testing], we were treating some patients with chemo who didn’t need it. We didn’t have a way of knowing who they were.”
Which tests help determine whether chemo is needed for early-stage breast cancer?
Doctors use a number of different tests — done on samples of tumor tissue removed during a biopsy or surgery — to help decide whether or not to recommend chemo.
These tests provide information on the characteristics of the tumor, including:
The results of these tests are included in your pathology report.
Unlike the standard pathology tests, genomic tests are only used for certain diagnoses.
One of the genomic tests that’s most often used in the U.S. (and that has the most research behind it) is the Oncotype DX Breast Recurrence Score Test. You may be a candidate for it if you’ve been diagnosed with early-stage, hormone receptor-positive, HER2-negative breast cancer that has either not spread to the lymph nodes or has spread to no more than three lymph nodes.
The test analyzes the activity of 21 genes in the tumor and assigns a score (a number between 0 and 100) that predicts the risk of the cancer recurring (coming back). It also calculates the benefits, if any, of chemo. In most cases, if you receive a high recurrence score, your oncologist will recommend that you receive chemo in addition to hormonal therapy after surgery. Chemo is more likely to be beneficial if there is a higher risk that the cancer could recur.
Sometimes the benefits of chemo aren't as clear because you've received a "borderline" recurrence risk score on a genomic test. In that situation, your can work with your oncologist to gather more information and make a decision together about whether chemo makes sense for you.
What’s the future of chemo for breast cancer?
Experts say that in the future, chemo will likely be used less in breast cancer treatment than it is today.
“We’re working towards moving away from moving chemo as the primary drug of choice,” says Dr. Roussos Torres. The goal, she explains, is to develop more targeted therapies that are better at eliminating tumors and have fewer side effects.
Targeted therapies are directed at certain molecules (often proteins) in breast cancer cells. They are usually less likely to harm normal, healthy cells than chemo is.
Breast cancer researchers are also focused on making treatment more personalized and minimizing the toxicity of treatment by:
gaining a better understanding of the factors that contribute to breast cancer recurrence risk and which individuals have a low, intermediate, or high risk
expanding the use of genomic tests to more people, especially those with stage III and stage IV breast cancer
discovering more breast cancer biomarkers (proteins, genes, or other molecules in blood, tissue, or cells) that new treatments can potentially target
“I think that all across the board, we’ll be making more personalized treatment decisions in the future, especially as we keep learning more and more about tumor genetics and about inherited (germline) genetic changes that play a role in breast cancer management,” says Dr. Tripathy.
This content is made possible, in part, by AstraZeneca, Gilead, Lilly, and Pfizer.
— Last updated on February 1, 2025 at 7:16 PM