Patients with metastatic breast cancer suffer less from their disease and the side effects of their treatment if they engage in physical training. They, for instance, are less tired, feel less pain and have increased their endurance. As a result, patients experience a better quality of life. This was shown in a comprehensive international study led by UMC Utrecht.

The study (PREFERABLE-EFFECT) was coordinated by the Julius Center of UMC Utrecht, led by Anne May, professor of clinical epidemiology of cancer survivorship.

UMC Utrecht collaborated on this research with healthcare centers from five European countries (Germany, Poland, Spain, Sweden, the Netherlands) and Australia. The Netherlands Cancer Institute is one of the partners in this consortium.

Complaints and side effects

Increasingly, we are able to cure cancer. But more and more, we are also living longer with cancer. In the latter case, people can no longer be cured. They remain under treatment but at the same time continue their ‘normal’ life as much as possible. They run a family, go to work and have an active social life. This is often complicated by the symptoms of their disease and the side effects of the treatments. They are tired, short of breath, in pain and in poor physical condition, for instance. These health problems affect their quality of life in an enormous way, which also applies to women and men with metastatic breast cancer.

Quality of life

Many studies have already shown that physical training has a positive effect on people with cancer. International guidelines already recommend physical training for patients whose breast cancer has not already spread. But for the first time, researchers are now investigating whether training also helps with metastatic cancer.

“Every year, about 3,500 people are diagnosed with metastatic breast cancer in the Netherlands,” Anne says. “The patients cannot be cured anymore. Their average survival is now two to three years, but one in four patients is still alive after five years. And there are also people known to survive as long as 15 years. They will remain under treatment for the rest of their lives and will thus have to keep on dealing with the symptoms. We want to help them to maintain their quality of life as much as possible.”

Nine months of training

357 patients (including two men) with metastatic breast cancer participated in the PREFERABLE-EFFECT trial. They were, on average, 55 years old, and many had bone metastases. Participants were randomly divided into two groups.

One half (the control group) received standard care, as well as exercise advice and a fitness watch. The other half (the exercise group) followed a nine-month exercise program, consisting of fitness, strength and balance training. The exercises included indoor cycling, bench presses and squats, for example. They worked out twice a week under the guidance of a physical therapist specialized in oncology, and once a week in the last three months.

Of course, when people are tired and in pain, it is quite difficult to motivate themselves to exercise. Anne: “During the project, we distributed questionnaires asking women and men with metastatic breast cancer: ‘What is a barrier for you to exercise?’ Some participants said they were afraid that working out would actually increase their pain. Now, we know that exercise can actually reduce pain. And, in terms of fatigue, it turned out that the participants actually felt better when they had participated in a workout.”

The patients in the exercise group therefore missed few workout classes, the researchers noted. “Every participant trained close to home, which also made it easier to keep up working out. And they usually exercised in a group, guided by the same physical therapist.”

Less complaints

After three, six and nine months, the groups were compared. They completed questionnaires, which were checked according to internationally recognized scientific criteria. As it turned out, participants in the exercise program were less tired and reported a better quality of life. Furthermore, they experienced less pain and shortness of breath.

“Based on these results, we recommend that people with metastatic breast cancer follow an exercise program supervised by a physical therapist. In addition, we would like to achieve that physicians make their patients more aware of the importance of exercise,” Anne says.

Even after the nine-month exercise program, many participants continued to exercise. “They were very motivated to continue. And that is precisely our intention. We think a program like this helps people to incorporate exercise into their daily routine. This study lasted only nine months, but we hope people will then make exercise a regular part of their treatment and daily life.”

What could be the underlying physical cause of this positive effect of exercise? “Several mechanisms in the body may play a role in this. For example, we think that exercise reduces inflammation levels in our body. We will investigate this further using blood samples that we have collected from our participants,” Anne clarifies.

Other types of cancer?

The exercise program is aimed at breast cancer patients but is it also suited for patients with other sorts of metastatic cancer? “We think exercise plays an important role in all types of cancer,” Anne explains. “But the symptoms may differ in each cancer type, and the treatments and associated side effects can also be different. For example, patients with breast cancer often get hormone therapy, experiencing other side effects than people having chemotherapy against colon cancer. For each sort of cancer, the type of symptoms and side effects must be looked at specifically. In the Netherlands, a comparable study is currently conducted for people with metastatic colon cancer (site in Dutch).”

Delighted with results

On 7 December 2023, Anne presented the first results of the PREFERABLE-EFFECT trial on the main stage of the leading San Antonio Breast Cancer Symposium in the United States. The results of the study will soon be submitted, for peer review, to a scientific journal.

The Dutch Breast Cancer Society is very pleased with the initial results of PREFERABLE-EFFECT. “As difficult as it can be for metastatic breast cancer patients to keep exercising, this study shows that it is worth challenging yourself,” responds Cristina Guerrero Paez, director of the Dutch Breast Cancer Society.