The Strongest Support in Metastatic Breast Cancer: Exercise

Supervised aerobic and resistance exercise can improve physical performance and muscle strength in patients living with metastatic breast cancer. These findings are based on data presented by Dr. Anne May at the Advanced Breast Cancer Eighth International Consensus Conference, namely new data from the PREFERABLE-EFFECT study.

“Exercise is already known to be effective in non-metastatic disease. The PREFERABLE-EFFECT study is the largest study to date investigating whether physical exercise is a feasible and effective option for patients with advanced breast cancer,” said Dr. May. She is Professor of Clinical Epidemiology of Cancer Survivorship at University Medical Center Utrecht and the Netherlands Cancer Institute in the Netherlands.

Study Details

There is a great need for interventions that can improve health-related quality of life for patients with metastatic breast cancer. Physical exercise has been shown to reduce side effects such as fatigue in this population.

The multinational, randomized and controlled PREFERABLE-EFFECT trial was designed to evaluate the effects of exercise on fatigue and health-related quality of life in patients with metastatic breast cancer. The study enrolled patients from five European countries and Australia, 357 patients in total. Most of these patients were receiving first- or second-line treatment, and most had bone metastases. All patients were enrolled between 2019 and 2022.

Patients were randomized to receive standard care or to participate in a 9-month exercise program delivered using an activity tracker. The exercise program included aerobic, strength and balance training with an instructor twice weekly for the first 6 months, followed by more semi-supervised sessions and a recommendation to be active for at least 30 minutes a day. Previous results from the study had shown that the exercise program improved both physical fatigue and measures of health-related quality of life.

Key Study Findings

New data from the study showed that patients randomized to the exercise arm had increases in muscle mass, muscle strength and physical performance. In patients in the exercise arm, muscle mass in the arms and legs increased compared with the control group by an average of 0,6 kg at month 3 and 0,48 kg at month 6. The skeletal muscle mass index increased in the intervention arm by an average of 0,22 kg/m² at month 3 and 0,18 kg/m² at month 6.

“Until now, evidence that physical exercise can increase muscle mass and strength in patients with metastatic cancer has been limited, because these patients were usually excluded from studies,” said Dr. May. “Treatments for the disease can cause serious side effects that affect quality of life, such as fatigue, nausea and pain. When the underlying disease, treatment itself and physical inactivity come together, skeletal muscle mass decreases. This adversely affects body composition, muscle strength and functional performance.”

“In patients receiving chemotherapy for localized or advanced breast cancer, low muscle mass has been associated with increased treatment-related toxicities, more frequent dose reductions, and poorer treatment outcomes and survival. Hormonal therapies are also linked to low muscle mass,” she added.

Patients in the exercise group reported better balance and experienced fewer falls in association with the increase in muscle mass and strength.

“The results of our study are important because lean body mass is associated with better treatment tolerance, a better prognosis and better overall health. Increased muscle strength is linked to better quality of life and a lower risk of mortality. These findings support the call to make supervised exercise, particularly resistance exercise, part of standard cancer care for patients with metastatic breast cancer,” said Dr. May.

Looking ahead, the ABC Global Alliance plans to create a Physical Activity Resource Center for patients with metastatic breast cancer, their caregivers, and exercise/health professionals in early 2026.

Conclusion

The PREFERABLE-EFFECT study shows that supervised aerobic and resistance exercise significantly increases muscle mass, muscle strength, balance and quality of life in patients with metastatic breast cancer. By reducing treatment-related muscle loss, exercise improves patients’ treatment tolerance and daily functioning. The findings strongly support that exercise is safe and effective for this patient group and should be part of standard care.