Stretching Reduces Tumour Growth in a Mouse Breast Cancer Model

A research found that mice with breast tumour who performed 10 min./day of yoga-inspired stretching had 52% less tumour growth (compared with the control animals),  in only 4 weeks.

There is growing interest in developing non-pharmacological treatments that could boost natural defenses against cancer and contribute to primary and secondary cancer prevention. Recent studies from Osher Center for Integrative Medicine at Harvard Medical School have shown that gentle daily stretching for 10 minutes can reduce local connective tissue inflammation and fibrosis.

Helene Langevin, MD, one of the authors of a new study said “We know, generally, that physical activity is beneficial in cancer patients but not why that is. Some animal models of exercise show benefit, others don’t.”

As mechanical factors within the stroma can influence the tumor microenvironment, the researchers investigated whether stretching would reduce the growth of tumors implanted within locally stretched tissues. They tested this hypothesis on mice.

Female FVB mice (N = 66) underwent bilateral injection of p53/PTEN double-null primary mouse mammary tumour cells into the third mammary fat pad. Mice were randomized to stretch vs. no stretch, and treated for 10 minutes once a day, for four weeks.

The researchers used an established protocol for stretching in mice in which the animals are held by the tail and gently lifted, allowing their front paws to grasp a bar. With minimal training, mice can hold this position without struggling for 10 minutes.

Stretching inhibits mammary tumour growth: (A) Downward facing mouse stretching, arrow indicates location of tumour. (B) tumour volume at euthanasia (N = 33  per group). (C) Tumour growth from weeks 2–4.  From Berrueta et al. 2018. CC

Tumour volume at end-point was 52% smaller in the stretch group, compared to the no-stretch group in the absence of any other treatment. Cytotoxic immune responses were activated and levels of Specialized Pro-Resolving Mediators were elevated in the stretch group.

These results suggest a link between immune exhaustion, inflammation resolution and tumor growth. However, the researchers still don’t understand the mechanism how stretching reduces tumor growth.

The authors suggested that stretching is a gentle, non-pharmacological intervention that could become an important component of cancer treatment and prevention. But they caution that this pre-clinical research in no way suggests that cancer patients should stretch instead of receiving cancer treatment. The research is at an early, investigative stage, and before it can be translated into a human protocol for clinical trials, further pre-clinical safety testing and dosage testing is needed. The team also wants to look at animal models with more advanced cancer that could metastasize to understand whether stretching may increase or decrease the spread of the disease.

Comment by Joseph Muscolino

I find so much of the controversy about stretching in recent years to be overblown; and I feel that many people are jumping to conclusions that are unwarranted in their interpretation of studies involving stretching. The overriding conclusions from most every study I have ever read show that stretching done on a regular basis does, in fact, increase flexibility of soft tissues, which must have a positive effect on movement function of the body. What I find fascinating about this research study is that we are looking at the possible benefits of movement and stretching to not only the musculoskeletal system, but to visceral pathologic conditions, like cancer. Movement therapists should LOVE this study!

The fact that simple stretching for only 10 minutes per day could reduce cancer tumour growth by 52% in this study involving mice is pretty amazing! Being a manual and movement therapy physician,  it is clear to me that the human body needs movement. And although, there are many wonderful aspects to our modern culture, the fact that we do not move anywhere near as much as we once did is certainly unfortunate. It is often said nowadays that “sitting is the new smoking.”

I would love to see more research studies that investigate all the possible parameters that movement and stretching might have to benefit our health with respect to cancer, and indeed all other life-threatening diseases. These studies might examine not only whether movement and stretching can help treat cancer once it has occurred, but also whether movement and stretching might be able to prevent the formation of cancer in the first place.