The Benefits of Exercise After Breast Cancer Diagnosis but Before Treatment

Research in recent years has demonstrated the positive effects of exercise on patients during and after cancer treatment. However, studies examining the long-term effects of exercise after a breast cancer diagnosis but before treatment begins are limited. CANTO is a large multicenter study conducted to address this gap. Its findings suggest that increasing exercise levels before treatment may reduce the risk of distant recurrence in patients with primary breast cancer. This article discusses the CANTO results and how exercise may contribute to survival in breast cancer.

The CANTO Study

Published on June 5, 2024, in the Journal of Clinical Oncology , the French CANTO study by Soldato and colleagues found that increasing exercise before treatment contributed to a longer distant recurrence-free interval in patients with breast cancer. A "distant recurrence-free interval" is the period during which cancer does not return at a site distant from the original treatment area. The study demonstrates particularly clear benefits of exercise in certain patient groups.

Study Details

This multicenter prospective cohort analysis—a study following a group over time—included 10,359 patients enrolled in CANTO between 2012 and 2018. Their exercise levels after diagnosis but before treatment began were assessed using the Global Physical Activity Questionnaire-16 (GPAQ-16). Exercise levels were standardized and expressed as metabolic equivalent task hours expended per week (MET-h/week). This unit makes patients' physical activity more objectively measurable and comparable.

Key Findings

During a median follow-up of 5.4 years, 502 of the 10 thousand patients experienced distant recurrence, meaning cancer spread to a site away from the original treatment area.

Across the entire patient group, the relationship between exercise level and distant recurrence-free interval was nonlinear. Exercise levels above 5 MET-h per week were associated with an inverse linear decline in distant recurrence-free interval events up to approximately 25 MET-h/week. Beyond this threshold, however, additional exercise provided no further benefit. Based on this finding, patients were analyzed according to exercise levels of < 5 MET-h/week (4,205 people, 40.6%) and ≥ 5 MET-h/week (6,154 people, 59.4%). Those exercising for 5 MET-h per week or more had a hazard ratio for distant recurrence-free interval of 0.82 (95% confidence interval [CI] = 0.61–1.00) compared with those exercising less.

This indicates that exercising for 5 MET-h per week or more, compared with exercising less, was associated with an 18% reduction in the risk of distant recurrence .

The benefit of exercise was evident in certain patient subgroups. The hazard ratios for distant recurrence-free interval comparing ≥ 5 MET-h/week with < 5 MET-h/week of exercise were:

• 0.59 (95% CI = 0.38–0.92) among 984 patients with hormone receptor (HR)-negative / HER2-negative disease
• 0.37 (95% CI = 0.14–0.96) among 392 patients with HR-negative / HER2-positive disease
• 0.64 (95% CI = 0.48–0.86) among 3,602 premenopausal patients

Conclusion: Exercise Is a Cancer Drug!

In conclusion, exercise after a breast cancer diagnosis but before treatment appears to reduce the risk of distant recurrence. The study also found that exercise was beneficial up to a certain level, beyond which there was no additional benefit. Its effect on distant recurrence-free interval varied according to cancer subtype and menopausal status. For example, the benefits were more evident in patients with hormone receptor-negative or HER2-positive disease and in premenopausal women.

Exercise is considered a very important cancer drug, with strong evidence supporting its role in cancer prevention and improving disease outcomes after diagnosis. Research shows that regular physical activity not only reduces cancer risk but also improves survival after diagnosis and lowers the risk of recurrence. Exercise is therefore regarded as an important therapeutic tool for breast cancer patients, improving both their physical health and the course of their disease.