Exercise during breast cancer treatment helps preserve CV function
A structured cardiovascular (CV) exercise programme during adjuvant breast cancer treatment provides significant protection against decline in CV function related to chemotherapy-induced cardiotoxicity, according to the EBBA*-II trial presented at SABCS 2018, indicating that physical activity during treatment for breast cancer can benefit patients.
“Treatment-induced cardiotoxicity is a major concern, and CV disease is a competing cause of death among breast cancer survivors,” said lead author Prof Inger Thune from Oslo University Hospital in Oslo, Norway, who noted that although survival rates for breast cancer have improved, many survivors have to deal with a declining CV function.
The multicentre, assessor-blinded, parallel-group study randomized 375 patients aged 18–75 years (mean age 55.2 years) with stage I/II breast cancer to either the intervention group (n=187) or the control group receiving usual care (n=188), 3 weeks after surgery. Fifty-seven percent of the women were on adjuvant chemotherapy, 67 percent were on endocrine therapy, and 78 percent received radiotherapy, with some patients receiving more than one treatment type. [SABCS 2018, abstract GS5-02]
The intervention involved a 12-month exercise programme consisting of supervised training sessions of 60 minutes twice a week for 12 months, which included moderate-to-high intensity stretching, weight bearing exercise led by physiotherapists, in addition to at least 120 minutes of home-based exercise. The exercise programme was individually tailored based on the CV fitness of each participant, as indicated by VO2max.
At 6 months, the exercise group did better than the control group at preserving their CV function, with a smaller decline in VO2max from baseline (2.7 percent vs 8.9 percent). Noting that both groups experienced a decreased VO2max nonetheless, Thune explained that this was expected in the months following surgery.
At 12 months, the exercise group had significantly improved VO2max by 2.3 percent from baseline (p=0.001), thus meeting the study primary endpoint, while O2max in the control group was 3.8 percent below baseline (p<0.001).
Among the patients receiving chemotherapy (n=295), those in the exercise programme almost returned to their presurgery CV strength at 12 months compared with those in the control group whose VO2max was still 6.4 percent below baseline (p<0.001).
In particular, the protective effect of the exercise programme extended to a subgroup of 212 patients who received taxane, who saw their VO2max rebounded to about 1.4 percent below presurgery levels at 12 months compared with 7.3 percent below baseline in the control group, even though this subgroup of patients had a greater decline in CV function at 6 months than the overall chemotherapy group.
“All subgroup of patients benefited from physical activity during breast cancer treatment,” Thune observed. She believed that exercise may also help improve quality of life and reduce fatigue, in addition to its CV benefits.
“Patients should discuss their plans with their doctor, but in general, our study supports incorporation of supervised clinical exercise programmes into breast cancer treatment guidelines,” she concluded. “Breast cancer patients receiving chemotherapy should be offered a tailored exercise programme based on pretreatment levels of physical function.”