Could weight loss medication prevent breast cancer recurrence?

There are so many physical changes people experience after breast cancer treatment: fatigue, joint pain, bone loss, hormonal fluctuations and weight gain. A groundbreaking new study might offer hope on two fronts—both for your weight management and your cancer recovery journey.

In a first-of-its-kind clinical study—TRIM-EBC—researchers at Baylor Scott & White are investigating whether tirzepatide, the active ingredient in certain popular weight loss medications, might prevent breast cancer from returning (known as recurrence) in people with overweight or obesity.

Through a better understanding of how weight and breast cancer are connected, this research could help people live better, for longer. Let’s find out how.

What is tirzepatide?

Tirzepatide is a medication that mimics two natural hormones: GLP-1 and GIP. GLP-1 and GIP are hormones your body produces to help regulate insulin levels, manage blood sugar and control your appetite. The medication works by binding to receptors in your brain that regulate hunger, making you feel fuller faster and for longer periods. It also slows stomach emptying, which helps control your blood sugar levels and reduces food cravings.

In the body, tirzepatide influences your metabolism, improves how your body responds to insulin and can lead to weight loss. Originally developed for people living with type 2 diabetes, it's now also FDA-approved specifically for weight management in people with obesity or who are overweight with weight-related health conditions.

Tirzepatide and breast cancer

So, what could be the link between weight loss and breast cancer?

Researchers want to understand how weight loss might affect cancer growth, hormones, metabolism and the immune system, for people who have a high risk of cancer recurrence.

"We hope this study will advance our understanding of breast cancer treatment and how to prevent breast cancer recurrence," said Joyce O’Shaughnessy, MD, a medical oncologist at Baylor University Medical Center, part of Baylor Scott & Health, and Celebrating Women Chair in Breast Cancer Research. Dr O'Shaughnessy is the co-investigator of the study with Ronan Kelly, MD, Director of Oncology at the Baylor Scott and White – Charles A. Sammons Cancer Center.

The research team is looking at something quite specific: whether tirzepatide-induced weight loss can prevent cancer from spreading within two years after detecting circulating tumor DNA (ctDNA) in the blood. ctDNA refers to small pieces of DNA that are released from cancer cells into the bloodstream. Detecting it can help doctors and researchers find cancer cells that aren’t visible on imaging scans.

How common is breast cancer recurrence?

Despite successful initial treatment, breast cancer recurrence remains a significant concern. 1 in 8 women in the United States will be diagnosed with breast cancer in their lifetime, so it’s quite likely you know someone who has been personally affected by breast cancer. Current strategies to prevent recurrence typically involve hormone therapy, chemotherapy or other cancer-specific treatments.

Understanding both how common recurrence is and what factors might increase your risk can help inform your treatment decisions and lifestyle choices. Here's what research shows about the risk of recurrence and the key factors that influence your personal risk:

• Overall recurrence rates: Approximately 25 to 30% of those with cancer experience recurrence at some point after initial treatment.
• Timing: Half of recurrences happen within the first 5 years after diagnosis, with the risk greatest in years 2 to 3 for high-risk cancers.
• Stage at diagnosis: Higher-stage cancers, which are more advanced when found, have greater recurrence risk, particularly those involving lymph nodes or larger tumors.
• Age: Younger people (under 35 to 40) often have more aggressive cancers with higher recurrence rates.
• Weight and lifestyle: Obesity and physical inactivity are associated with increased recurrence risk, particularly for hormone receptor-positive cancers. Hormone receptor-positive cancers grow in response to hormones, such as estrogen or progesterone, and excess body fat can increase hormone levels, which may “feed” the cancer.

The weight-cancer connection

If you've been treated for breast cancer and struggle with weight management, this research could be significant. The link between weight and breast cancer isn't new information; one study of over 180,000 women above age 50 demonstrated that sustained weight loss was linked to a lower risk of developing breast cancer in the first place . For overweight women who have a diagnosis of breast cancer, finding effective interventions has been challenging.

"Obesity is a well-established risk factor for breast cancer, and research suggests that weight gain after diagnosis increases the risk of the cancer being fatal," Dr. O'Shaughnessy said. This new study takes that knowledge a step further by exploring whether medication-assisted weight loss could actually prevent cancer from returning or spreading in women at higher risk.

Finding the right participants for the study

In November 2024, Baylor Scott & White began recruiting approximately 500 women for the study. As not everyone has detectable ctDNA in their blood, the selection process is quite specific.

“We will need to recruit roughly 500 women to find 48 patients who test positive for ctDNA and are eligible to receive treatment," Dr. O'Shaughnessy said. "After the first 20 patients receive treatment, we will pause recruitment to see how well the treatment is working and determine if we can enroll the next 28 patients."

To find eligible patients, researchers consider if the person has:

• Early breast cancer that is ER-positive, which is sensitive to estrogen
• Early breast cancer that is HER2-negative, which means it doesn’t contain proteins that fuel growth
• Early breast cancer that is lymph node-positive, which means it has spread to nearby lymph nodes
• A body-mass-index (BMI) of 27 kg/m² or above
• ctDNA-positivity on testing provided by the study
• No evidence or clinical suspicion of metastatic breast cancer

Eligible people who receive tirzepatide treatment in the study aren't required to reach or maintain a specific BMI. Instead, researchers will measure the percentage of weight that people lose based on their starting weight. This approach recognizes that each person's body and weight journey is unique, focusing on improvement rather than arbitrary numbers.

Long-term follow-up and potential impact

During the Baylor Scott & White study, participants will be followed for five years to monitor whether the cancer returns and spreads to other parts of the body. This long-term perspective is crucial for understanding the lasting effects of the intervention.

"The research could impact the tens of thousands of people who are overweight or obese and are diagnosed with high-risk breast cancer each year," Dr. O'Shaughnessy said. This could help many people who are living with breast cancer and also dealing with excess weight, which is a common challenge.

Looking ahead

While the study is still in its early stages, it represents an innovative approach to cancer and plays a key part in how Baylor Scott & White is working to improve early detection at the Texas Cancer Interception Institute.

For those currently in breast cancer treatment or recovery, maintaining open communication with your healthcare team about managing your weight is important. And while not everyone will qualify for this specific study, the findings could eventually inform care guidelines that benefit many more people.

If successful, this research could open new doors for using weight loss medications not just for managing weight, but as part of a strategy to prevent cancer recurrence— giving breast cancer survivors another tool in their recovery journey and helping them thrive after their diagnosis.

Find out if the TRIM-EBC clinical trial is right for you.