Women’s cancers: scan-guided plan let some with breast cancer skip chemo

Here is some good news from the world of women’s cancers. For some women with early HER2-positive breast cancer, a scan taken early in treatment showed that chemotherapy could be left out, and they were still doing very well five years later.

If you or someone you love faces this diagnosis, that is a real reason for hope. Chemotherapy can be hard on the body, and this research shows that a smarter plan can spare some women from it. Of course, decisions about treatment belong to you and your oncologist. This article gives you something useful to bring to that conversation.

How the study worked

PHERGain was a randomized phase 2 trial of women with early, operable HER2-positive breast cancer, followed for a median of 5.6 years. The results were published on Oct. 29, 2026, in Nature Medicine. The 92.4% figure below describes a group of women sorted after the trial began, so it shows how those women did rather than proving that skipping chemotherapy works for everyone.

What does “scan-guided” mean?

HER2 is a protein on the surface of some breast cancer cells that pushes them to grow. Two medicines, trastuzumab and pertuzumab, block it. Usually they are given together with chemotherapy.

In this trial, one group of women got the usual chemotherapy plus those two medicines. The other group, called group B, started with the two medicines alone, plus hormone therapy if the tumor needed it. After two cycles, a PET scan checked whether the tumor was responding. Women who responded kept going without chemotherapy. Women who did not respond, or who still had cancer in the tissue after surgery, got chemotherapy.

What they found

About 9 in 10 women in group B were free of invasive disease at five years. The exact figure was 89.5%, among 267 women.

The best news came from the women who responded on the PET scan and had no cancer left at surgery, all without chemotherapy. There were 86 of them. About 9 in 10 were free of invasive disease at five years, exactly 92.4%. Only one of those women had the cancer return in a distant part of the body.

The researchers also looked at circulating tumor DNA. These are tiny pieces of tumor DNA that show up in the blood. Women with detectable tumor DNA did worse. Women whose tumor DNA cleared were more likely to have no cancer left at surgery, and they did better over the long run. This suggests a simple blood test could one day help fine-tune treatment for each woman.

Why this matters

Chemotherapy can bring side effects that last, such as fatigue, hair loss, nerve damage and, in some women, heart problems. A way to spot the women who do not need it, using a scan early in treatment, could spare many of them. These five-year results continue to support that approach.

What you can do today

If you or someone close to you has early HER2-positive breast cancer, take one minute to write this question in your phone’s notes app: “Can my treatment be adapted to how the tumor responds, and is there a clinical trial that does this?” Bring it to your next oncology visit. You can also look up trial NCT03161353 on ClinicalTrials.gov to see how this study was described.