Heart disease patients are less likely to die of cancer if they are fit, suggests an observational study in more than 12 000 patients presented today at EuroEcho-Imaging 2017.
"There is evidence that higher levels of physical activity are associated with lower risk of several cancers," said lead author Dr Jesus Peteiro, a cardiologist at University Hospital A Coruna, A Coruna, Spain. "However, this association comes mainly from observational studies in which people self report their physical activity."
This study examined the association between physical fitness assessed by exercise echocardiography and death due to cancer. The study included 12,615 patients with known or suspected coronary artery disease referred for exercise echocardiography. Patients were 62 years old on average and 63% were men.
Exercise echocardiography was performed using a treadmill. For each patient the achieved metabolic equivalents (METs), which is a measure of oxygen consumption by the heart, was calculated.
Good functional capacity was defined as ten METs or more, based on previous studies that reported overall mortality of less than 1% per year in patients achieving ten METs during exercise echocardiography. Ten METs is equivalent to walking 12 minutes at maximal capacity on a treadmill (by a standard Bruce protocol). Patients were divided into two groups according to whether they had good functional capacity (ten METs or more) or not (less than ten METs).
Patients were followed up for death due to cancer. The association between functional capacity and death due to cancer was calculated after adjusting for clinical characteristics and resting echocardiography.
During an average follow-up of 4.7 years, 669 patients died of cancer. The researchers found that a worse functional capacity was significantly linked to a higher risk of cancer-related death. Cancer-related death was half in patients with good functional capacity (0.8%) compared to those without good functional capacity (1.5%; p<0.001).
Older age, male gender, and smoking were also associated with increased risk of death due to cancer, with hazard ratios of 1.05 (per year difference), 2.15, and 1.52, respectively.
Other measurements during exercise echocardiography that mainly assess the presence and extent of coronary artery disease, such as ischaemia or fixed wall motion abnormalities, were not associated with cancer-related death.
Dr Peteiro said: "The 'exercise part' of an exercise echocardiography study predicts cancer-related death in patients referred for this test. Fit patients, as demonstrated by exercise testing, have less chance of death due to cancer. These patients can be reassured that their mortality rate is lower than that of patients with lower functional capacity, not only due to a lower rate of cardiac-related mortality, but also due to a lower rate of cancer-related death."
"We knew from previous studies that being fit is a good idea for patients with coronary artery disease because of the beneficial cardiovascular effects," said Dr Peteiro.2 "Now we can see that this is also good for decreasing the risk of cancer-related death."
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