Exercise during anthracycline or anti-HER2 therapy: evidence is thin and inconsistent

Design

Systematic review and meta-analysis of randomised trials; RoB 2 and GRADE applied

Population

513 women with breast cancer on anthracyclines and/or anti-HER2 therapy (7 trials; 2 pooled)

Primary outcome

LVEF, global longitudinal strain and cardiac biomarkers at about 4 months

Effect

LVEF MD 0.07 (95% CI -1.38 to 1.52); GLS MD -0.10 (95% CI -0.79 to 0.58)

This meta-analysis asked whether structured exercise preserves ejection fraction, global longitudinal strain or cardiac biomarkers in women with breast cancer on anthracyclines or anti-HER2 therapy. Seven randomised trials (513 women) were included, but only two could be pooled, and most had some concerns or high risk of bias.

There was no difference in LVEF (mean difference 0.07, 95% CI -1.38 to 1.52) or GLS (-0.10, -0.79 to 0.58) at the end of anthracycline treatment, about 4 months. The intervals were wide, compatible with benefit, no effect or harm. Biomarker results were too varied to pool. Clinical events, survival and heart failure with preserved ejection fraction were not reported.

Exercise remains reasonable for general health and fatigue in cancer treatment, but this review does not show a cardioprotective effect. It is better read as a gap in the evidence than as evidence that exercise does nothing.

• Continue to monitor LVEF or strain in line with your cardio-oncology protocol; exercise does not replace it.
• Encourage activity for general health, but do not promise cardioprotection.
• Ask for exercise to be started only after oncology agrees, particularly with low counts or symptoms.
• Avoid quoting this as proof of no effect; it was underpowered.

Why it matters

It stops a popular cardio-oncology idea being taken as established, and names what future trials must measure.

Don't overread it

Only two small trials were pooled with low-certainty evidence, so this does not show that exercise is ineffective.

The statistics, in plain English

A mean difference of 0.07 LVEF points with an interval of about -1.4 to +1.5 means the pooled result was close to zero, but with only two trials the interval is too wide to rule out a clinically useful gain or a small loss.

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