A new study explains how aerobic and resistance exercise can increase life expectancy for individuals who have successfully finished breast cancer treatment.

According to National Cancer Institute estimates, there were about 252,710 new diagnoses of breast cancer in the United States in 2017. The life expectancy following treatment for this type of cancer is quite good, with a 5-year survival rate of 89.7%.

However, cancer treatment is often associated with the onset of metabolic syndrome, a cluster of related conditions including heart disease, hypertension, obesity, high blood sugar, and insulin resistance. Metabolic syndrome has also been linked to a poorer survival rate among breast cancer survivors.

That is why researchers from the University of Southern California in Los Angeles, CA, have set out to see how post-treatment life expectancy might be prolonged through regular exercise, which can help to tackle or prevent the onset of metabolic syndrome.

"Many people don't know the no. 1 cause of death for breast cancer survivors is heart disease, not cancer," says lead author Christina Dieli-Conwright, explaining why regular exercise might help to increase life expectancy.

The study's findings were published yesterday in the Journal of Clinical Oncology.

'Exercise is a form of medicine'

"In breast cancer patients, metabolic syndrome is exacerbated by obesity, a sedentary lifestyle, and receipt of chemotherapy," Dieli-Conwright explains.

In their paper, the authors also note that individuals experiencing metabolic syndrome have a 17% higher chance of being diagnosed with breast cancer. They may also be more likely to experience cancer recurrence after treatment, and may have a shorter life expectancy.

Taking these considerations into account, the research team hypothesized that adherence to a regular exercise schedule might improve the long-term survival rate by addressing weight gain and its associated disorders.

Dieli-Conwright and team conducted a randomized trial, working with 100 individuals who had successfully undergone breast cancer treatment less than 6 months before the study was due to begin.

At the start of the study, approximately 46% of participants were deemed obese, while approximately 77% had been diagnosed with metabolic syndrome.

The intervention consisted of three, weekly one-on-one training sessions over a period of 4 months, including weight-lifting exercises and a minimum of 150 minutes of moderate aerobic exercise.

Following the 4-month training program, the participants who engaged in this routine experienced significantly improved health; only 15% of them were found to have metabolic syndrome, compared with 80% of the study participants in the control group.

The researchers also noted that the women who participated in the fitness program gained muscle mass and shed excess fat, and that regular exercise reduced participants' risk of developing heart disease.

Moreover, fitness program participants also saw a 10% decrease in blood pressure and a 50% increase in high-density lipoprotein (HDL), or the so-called "good cholesterol," which absorbs other types of cholesterol, carrying them back to the liver to be eliminated from the system.

Dieli-Conwright points out that obesity can cause inflammation, which, in turn, might facilitate tumor growth and cancer recurrence following treatment.

A study Dieli-Conwright conducted last year, in which she looked at blood samples and fat biopsies sourced from 20 cancer survivors with obesity, showed that individuals who engage in regular exercise see less inflammation in blood cells, and they also have a better overall inflammation response.

The researcher stresses the importance of exercise to maintining good health, adding that she and her team are committed to conducting further studies addressing the therapeutic potential of such routines.

"Exercise is a form of medicine. Both of these studies support that idea, and we will continue to conduct studies to supplement traditional cancer therapies."

Christina Dieli-Conwright