Surprise Finding: Sport and Exercise May Shrink Tumors

A notable study published on 1 February 2022 reported that neoadjuvant (preoperative tumor-shrinking) chemotherapy combined with a structured "prehabilitation" exercise program in patients with esophageal (food pipe) cancer produced tumor shrinkage. Compared with a control group of patients who did not exercise, these patients showed significant tumor regression (shrinkage) and tumor downstaging.

British Journal of Sports Medicine published the research, whose lead author Andrew Davies of Guy's and St. Thomas' Hospitals says, “The strength of the findings came as a surprise to us” and adds:

“We were aware of some evidence from animal models supporting that exercise increases the benefit of chemotherapy, but this was not the first interesting outcome of this study. However, when the chemotherapy response results started coming in, it became impossible not to see the differences between the groups."

The team states in the study: “Tumor downstaging and response to chemotherapy are the most important predictors of disease course in esophageal cancer. These structured exercise programs may benefit advanced cancers through improved immunological and/or inflammatory regulation.”

Exercise as a Cancer Drug

The study included 40 patients with esophageal cancer: 21 followed a structured prehabilitation exercise program, while 19 continued standard care. The two groups had comparable main characteristics. All patients completed four cycles of neoadjuvant chemotherapy with epirubicin, cisplatin and 5 fluorouracil (ECF), followed by surgery.

All had been diagnosed with operable adenocarcinoma of the lower esophagus or gastroesophageal junction, and all received advice on nutrition, physical activity and smoking cessation from specialist nurses, dietitians and physiotherapists. Patients who agreed to prehabilitation also undertook aerobic and strength training in a gym 5-6 times a week. This totaled 150 minutes per week until the last day before surgery.

The team analyzed all clinical data and found tumor shrinkage. Compared with the control group (7 of 19 patients, 36.8%), this shrinkage was observed in far more patients in the exercise group (15 of 20 patients, 75%).

These are the first results from a clinical trial in esophageal cancer to show that exercise contributes significantly to tumor shrinkage.

However, the study is limited by its small patient group and nonrandomized patient selection.

What Role Does Exercise Play in Tumor Shrinkage?

Davies says the mechanisms by which exercise may improve tumor control probably involve many factors and are somewhat complex.

“In the simplest terms, a plausible theory is that patients who exercise can deliver more blood and oxygen to peripheral tissues, which in turn increases delivery of chemotherapy to a target tumor.”

Davies also noted that the study revealed “some important differences in body composition and markers of immunity and inflammation,” all of which are “associated with chemotherapy response rates at the basic-science level.” In other words, exercise may positively modulate the immune system against the tumor.

Patients in the exercise group had a higher mean T-lymphocyte count after neoadjuvant chemotherapy than controls, and the groups differed in markers of immunity and inflammation, including interleukin-6, interferon gamma and tumor necrosis factor alpha.

The exercise group also showed significant improvement in Fat-Free Mass Index. However, although Davies describes the differences as “very interesting” and “hypothesis-generating,” he stresses that they “do not want to overstate these associations.”