Are you at risk for cancer? Chances are if you eat a diet high in saturated fat, don’t exercise regularly, smoke cigarettes daily, and can be classified as obese, you are at extremely high risk of developing and dying from cancer (not to mention heart disease and/or diabetes).
But if you are reasonably physically active, eat a relatively healthy diet, don’t smoke cigarettes, and are within striking distance of normal weight for a person of your height and build, what are you odds then? One recent study showed that men with these characteristics were 62 percent less likely to die from cancer and were likely to live 12 years longer than men who were inactive, smokers and obese.
This would seem to indicate that following a healthy lifestyle over the long-term confers significant protection against dying from cancer. That’s all well and good, but figuring out whether you are doing enough to achieve this long-term cancer death protection is a little tougher. There is no precise prescription offered by scientists that defines how much exercise, how much healthy food, and what exact weight level offers optimum protection.
Some studies show benefit from low-intensity exercise while others show benefit for high-intensity exercise. Other studies examine the benefits of a Mediterranean-style diet versus a Japanese-style diet. Weight-related research shows some benefit from being a little overweight versus being underweight.
It would be nice to have a shorthand way of assessing one’s cancer risk that was easy and quick to measure regardless of what lifestyle choices one makes. And guess what, there is such a measure: resting heart rate.
Regular Peak Health Advocate readers will recall we wrote recently about the strong diagnostic value of resting heart rate as it relates to all-cause mortality risk and cardiovascular disease mortality risk. Well, this month a new study was published online ahead of print that specifically examined the risk of cancer death in men using resting heart rate as the primary diagnostic measure. This study found that men with the highest resting heart rates (greater than 73 beats per minute) were 140 percent more likely to die from cancer than those with the lowest resting heart rates (less than 60 beats per minute).
To determine your resting heart rate in the same manner as was done in this study, first lie down for five minutes to put your body at rest. Then, while still lying down with your face up, place two fingers on your wrist to detect your pulse (or on your neck where the carotid artery runs along your windpipe) and count the number of beats your heart registers in a 60-second period. For greater precision, you can use a pulse rate monitor (typically a watch-like device that has electric sensors in it, or wirelessly picks up signals from a chest band sensor) or a pulse oximeter (a fingertip device that records pulse rate and the oxygen level of your blood).
In this study, 6,101 French men with an average age of 48 had their resting heart rates assessed at the outset of the study (along with a number of other diagnostic measures). The study participants were then followed over a 25-year period, periodically returning to provide fresh diagnostic measures.
At the end of the 25-year period, researchers determined 1,625 men had died with 771 of those deaths related to cancer (47 percent of all deaths during the follow-up period). As an aside, only 435 of the deaths were related to cardiovascular disease (27 percent).
The researchers then plotted the resting heart rates taken at the outset of the study and found a striking connection between baseline resting heart rate and cancer mortality risk (as well as cardiovascular disease mortality risk and all-cause mortality risk). The researchers expressed this connection by comparing the relative number of cancer deaths in four quartiles of resting heart rate. The relative cancer death risk rates for quartiles 2-4 are shown below in comparison to quartile 1:
- Quartile 1: Less than 60 beats per minute
- Quartile 2: 60-66 beats per minute — 60 percent higher risk
- Quartile 3: 67-73 beats per minute — 60 percent higher risk
- Quartile 4: Greater than 73 beats per minute — 140 percent higher risk
One caution to readers, the study authors noted these results are applicable to men only. That said, other studies have shown a strong connection between resting heart rate and premature death risk in both men and women. In one such study, a different group of researchers found increasing all-cause mortality risk at successively higher resting heart rate ranges in both men and women, although there were modest differences between men and women in each qvuartile (and the specific heart rate quartiles were not the same as the quartile ranges discussed in this article).
The Cancer Connection
So what is the underlying connection between resting heart rate and cancer death risk?
It’s a good question because researchers are unsure of the precise underlying connection. The authors of the cancer risk/heart rate study explained, “The mechanisms that could explain the association between heart rate and cancer mortality are unclear. Is heart rate a marker of risk for developing cancer, or a marker of risk of dying if one individual develops cancer?
“One possibility is that heart-rate increase might be a marker of chronic stress and anxiety, which may in turn be related to an increased risk for cancer. Recent data suggest that the link between chronic stress and cancer might be related to genetic instability as a consequence of telomere length reduction and telomerase activity decrease. [Editor’s note: A telomere is a portion of our DNA strands that is disrupted/corrupted in cancerous cells.]
“Another possibility is that low-grade inflammation which is present in certain malignant conditions may play a role although it is not known to what extent such inflammation might be associated with heart-rate increase.”
Yet despite the unknown connection, the researchers indicated that resting heart rate was a more effective measure of cancer death risk than most other researched measures, “With the exceptions of tobacco exposure for lung cancer and familial history for colorectal malignancy, there have been few risk factors associated with cancer death which confer as substantial a relative risk, as did heart rate in the present study.”
What to Do If You Are at Risk
So as we each continue our efforts to live a healthier lifestyle, it makes good sense to periodically check our resting heart rates. This study combined with others on the same topic has clearly shown that high resting heart rate levels are strongly correlated to premature death.
For male and female readers with high resting heart rates, research studies have shown that losing weight, cutting down on the saturated fat content of one’s diet, and increasing physical activity all contribute to lowering resting heart rate. Substantial improvements in resting heart rate can be achieved (5-10 beats per minute) in a relatively short time period (3-6 months) if such lifestyle improvements are aggressively pursued.
For example, a 2009 study examining the effects of a 12-week aerobic exercise program in 58 obese men and women found that the subjects, on average, lowered their resting heart rate by 5-9 beats per minute by the end of the program. The exercise protocol followed was not described in great depth in the study results – participants exercised five times a week over the 12-week period (presumably on an exercise cycle) at an intensity level of 70 percent of maximum heart rate for as long as it took each subject to burn 500 calories during each workout session (many treadmills, stationary cycles and elliptical training machines record calories burned based on your entered body weight).
 Lee CD, et al. Combined Impact of Lifestyle Factors on Cancer Mortality in Men. Ann Epidemiol. 2011 Jun 15. [Epub ahead of print]
 Jouven X, et al. Heart Rate and Risk of Cancer Death in Healthy Men. PLoS ONE 6(8): e21310. [Epub ahead of print]
 Tverdal A, et al. Heart rate and mortality from cardiovascular causes: a 12 year follow-up study of 379,843 men and women aged 40–45 years. European Heart Journal (2008); 29: 2,772–2,781.
 King NA, et al. Beneficial effects of exercise: shifting the focus from body weight to other markers of health. Br J Sports Med 2009; 43: 924-927.