Exercise: A Powerful Tool in the Fight Against Cancer and Heart Disease
Exercise is a game-changer for cancer patients and survivors, offering a non-pharmaceutical approach to enhance cardiovascular health and improve overall well-being.
While advancements in cancer treatment have led to increased survival rates, they've also brought new challenges, including cancer therapy-related cardiac dysfunction (CTRCD) and subsequent cardiovascular disease (CVD) among survivors. This is a critical issue, as recent data shows that CVD-related deaths often surpass cancer-related deaths beyond 5-7 years post-diagnosis, highlighting the urgent need for effective cardioprotective strategies.
But here's where it gets controversial... While pharmacological interventions are well-established for certain cancer therapies, the role of non-pharmacological interventions, particularly exercise, is gaining significant traction.
Exercise has proven benefits for cancer patients, improving fatigue, quality of life, and physical functioning. This has led to guideline recommendations for oncologists to prescribe aerobic and resistance exercises during treatment to mitigate adverse effects.
The CV Benefits of Exercise in Cancer Patients
Exercise plays a crucial role in addressing cardiovascular risk and improving outcomes for cancer patients. It enhances skeletal muscle metabolic efficiency, leading to better glycemic control, and favorably alters body composition by reducing fat mass and increasing lean muscle.
Additionally, exercise improves cardiorespiratory fitness, as evidenced by a recent meta-analysis showing significant improvements in peak oxygen consumption (VO2peak) after 8-12 weeks of exercise training in breast cancer patients exposed to anthracyclines and/or trastuzumab. This aligns with other studies, suggesting that exercise not only prevents a decline in VO2peak during cancer treatment but can even enhance cardiorespiratory fitness beyond pretreatment levels.
And this is the part most people miss... While exercise consistently improves cardiorespiratory fitness, its effects on cardiac function are more nuanced. Several studies have shown no significant difference in resting left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS) following exercise training. However, exercise training can improve exercise cardiac reserve, which may be a more sensitive marker of CTRCD than resting cardiac function.
A study on pediatric cancer survivors found that exercise cardiac reserve could differentiate survivors with impaired cardiorespiratory fitness from those without, despite similar resting cardiac function. Similarly, a randomized controlled trial in breast cancer patients showed that while resting echocardiographic LVEF and GLS remained unchanged, exercise cardiovascular magnetic resonance detected greater improvements in cardiac reserve in the exercise group.
These findings suggest that dynamic assessments of cardiac function, rather than static measures, may better capture the impact of exercise training on preventing CTRCD.
Exercise also influences biomarkers used for early detection of CTRCD. A recent RCT demonstrated that exercise attenuated chemotherapy-induced elevations in troponin levels, indicating a potential cardioprotective effect. However, B-type natriuretic peptide (BNP) levels remained unchanged. In contrast, another study found that structured exercise during adjuvant chemotherapy in breast cancer patients resulted in significantly lower N-terminal pro-BNP levels at 1-year follow-up.
These findings suggest that the timing of troponin measurement is critical for detecting acute changes in cardiac stress. Further research is needed to determine if exercise provides long-term protection against BNP elevation, a key biomarker for myocardial stretch or volume overload and a critical factor in diagnosing and assessing the severity of both systolic and diastolic heart failure.
The Survival Advantage of Exercise
Emerging data suggests that exercise training post-cancer treatment may confer a survival benefit, driven by improvements in cancer-related outcomes. In a recent trial, individuals who underwent surgery and adjuvant chemotherapy for colon cancer were randomly assigned to either a 3-year supervised exercise and behavioral support intervention or health education only. Over an 8-year follow-up, the exercise group had a 37% reduction in mortality compared to the health education group.
The disease-free survival benefit from exercise was primarily due to reduced liver recurrence and new primary cancers. Participants in the intervention group achieved a mean of 10 MET-hours per week of exercise, equivalent to approximately 150 minutes of brisk walking weekly, which was associated with significant improvements in cardiorespiratory fitness.
Conclusion
Exercise is a recommended therapy during and after cancer treatment due to its effectiveness in improving fatigue, physical functioning, and quality of life. It's an essential intervention in cardio-oncology for mitigating CTRCD and improving survival in select cancer patients. The strongest evidence is in breast cancer, where exercise has been shown to improve cardiorespiratory fitness, reduce CVD risk factors, and enhance exercise cardiac reserve in patients treated with conventional therapies.
Looking ahead, integrating exercise into oncology care presents new opportunities, especially with the increasing use of T-cell therapies and targeted treatments. Investigating whether exercise can mitigate the off-target CV effects of these novel therapies is a key area for future research. Additionally, innovative approaches to prescribing and delivering exercise, such as personalizing interventions with artificial intelligence, require further exploration.
Finally, integrating exercise into comprehensive cancer care plans is crucial. It should be used not only for symptom management but also as a proactive strategy to preserve and protect cardiovascular health throughout the cancer journey.
