ESMO 2025 Breast Cancer Research Takeaways

The European Society for Clinical Oncology (ESMO) Congress 2025 will take place Oct. 17-21 in Berlin, and will be attended by thousands of people who all have one goal: providing the best care for people with breast cancer.

The ESMO 2025 Breast Cancer meeting, a companion conference focused on breast cancer, took place May 14-17 in Munich.

We’re bringing you the top breast cancer research highlights from both meetings.

Among more than 6,230 women with a BRCA mutation who were diagnosed with early-stage breast cancer while pregnant, one out of three went on to have another pregnancy, according to an analysis of information from a large international study. When compared with women who didn’t have another pregnancy, there were no differences in survival among the women. “No safety concerns emerged regarding material or fetal outcomes,” said Marta Perachino, MD, medical oncologist and clinical investigator at Vall d’Hebron Institute of Oncology, who presented the research.

Doctors have been wondering what the best treatments are for people diagnosed with advanced-stage estrogen receptor-positive, HER2-negative breast cancer that came back (recurred) or grew during or after treatment with a CDK4/6 inhibitor. Would another CDK4/6 inhibitor offer benefits? Should it be combined with another medicine?

The latest results from the EMBER-3 study show another CDK4/6 inhibitor can be effective. The combination of Verzenio (chemical name: abemaciclib), a CDK4/6 inhibitor, and imlunestrant, a new selective estrogen receptor downgrader (SERD), offers better progression-free survival (the amount of time a person lives without the cancer growing), (9.3 months), than imlunestrant alone (3.7 months) in people who previously received a CDK4/6 inhibitor (Ibrance, also known as palbociclib, in most cases).

Final survival results from the APHINITY study continue to show that adding Perjeta (chemical name: pertuzumab) to Herceptin (chemical name: trastuzumab) and chemotherapy after surgery for early-stage HER2-positive breast cancer reduces the risk of the cancer coming back (recurrence) and improves survival.

After 10 years of follow-up, overall survival rates were 91.6% with Perjeta, Herceptin, and chemo, compared to 89.8% with just Herceptin and chemo. Adding Perjeta also reduced the risk of recurrence. Ten-year disease-free survival rates (the percentage of people who were alive with no recurrence after 10 years) were 87.2% for people who received the three medicines and 83.8% for people who received only Herceptin and chemo.

No new heart side effects were seen with longer follow-up.

“After 10 years, the APHINITY trial clearly shows a statistically significant and clinically meaningful improvement of the overall survival,” said Sibylle Loibl, MD, PhD, chair of the German Breast Group who presented the research. “Adding Perjeta to a standard adjuvant treatment is most beneficial for people with HER2-positive breast cancer with lymph node-positive disease who are at high risk of recurrence.”

Gaining more than 5% of body weight after a breast cancer diagnosis increased the risk of dying from the disease for women living with healthy weight or overweight before diagnosis.

The results come from an analysis of more than 6,800 women in the Nurses’ Health Study.

The women were diagnosed between June 1978 and June 2018. They were followed for about four to 15 years.

Before diagnosis, women with a BMI of less than 25 (healthy weight) who gained more than 5% of their body weight had a 32% higher risk of dying from breast cancer than women who didn’t gain that much weight. Women with a BMI of 25-29.9 (overweight) before diagnosis had a 37% higher risk of dying from the disease if they gained more than 5% of their body weight. In contrast, women with obesity didn’t have a higher risk if they gained weight.

The researchers found that losing weight or gaining less than 5% of body weight didn’t affect the risk of dying from breast cancer. They’re not sure why this is.

“We aimed to identify specific weight gain thresholds associated with the risk of breast cancer mortality to provide guidance for professionals managing breast cancer patients,” said Sixten Harborg, MD, a physician and PhD fellow at Aarhus University Hospital in Denmark, who presented the research.

What is the future for young women with breast cancer? What are their unique needs and challenges? What questions do they have that older women don’t have? Anne Partridge, MD, MPH, addressed these issues during her keynote address, “A decade of BCY [Breast Cancer in Young Women]: What we have done and where we are going?”

Partridge is interim chair of the Department of Medical Oncology at the Dana-Farber Cancer Institute, where she also serves as director of the Adult Survivorship Program and co-founder and director of the Program for Young Adults with Breast Cancer.