Aging and Cancer

Elizabeth C. Clipp, PhD, RN

Wendy Demark-Wahnefried,
PhD, RD, LDN

Wendy Demark-Wahnefried, PhD, RD, LDN
Department of Surgery
Center for Aging
School of Nursing

Elizabeth C. Clipp, PhD, RN
Center for Aging
School of Nursing
Department of Medicine

Duke University Medical Center
Durham, North Carolina

Although cancer occurs at all ages, the highest incidence and mortality rates occur in those over 65 years of age. Research continues to assess the best prevention and early detection efforts in this age group. The elderly are the most likely, compared to other age groups, to have pre-existing health problems, such as chronic conditions, physical limitations, and decreased physiological functioning. Coupled with the reduced economic status and medical insurance coverage, these individuals often face obstacles to effective cancer prevention strategies. These include efforts to prevent not only primary, but also secondary malignancies.


More Older Americans, More Older Cancer Survivors

Currently, there are over 10 million cancer survivors in the US, comprising 3%--4% of the total population. Because cancer is associated with aging, a clear majority of these cancer survivors-65%--are = 65 years old.(1) The aging of the American population-now at 35 million in the = 65 years group and expected to double by 2030(2)--coupled with improved cancer cure rates, forecasts a future of increasing numbers of older cancer survivors-a group that is expected to double over the next 50 years,(3) leading to profound implications for cancer prevention (both primary and secondary) in the coming decades.

Obviously, then, faced with this large looming public health concern, these data call for significant efforts aimed at prevention and early detection in the older population. The first half of the 21st century will witness not only increasing numbers of older Americans, but also older American cancer survivors. Clinicians and investigators will thus be presented with a heretofore unseen challenge to prevent cancer in these two ever-growing populations. The challenge is to successfully develop and integrate cancer prevention strategies into the daily lives of the elderly.


Secondary Prevention a Prime Concern for the Elderly

Although the dramatic increase in the numbers of older cancer survivors is encouraging, there is a downside. The impact of cancer on the elderly is significant and associated with several long-term health and psychosocial sequelae.(4) Compared to age-matched controls, this population is at greater risk for other cancers, as well as cardiovascular disease, osteoporosis, diabetes, and functional decline.(3-5). One recent study suggests that older cancer survivors have almost a two-fold increase in having at least one functional limitation; with a single additional co-morbid condition this risk increases to 5.06 and up to 11.80 in the presence of more than one co-morbid factor.(5) At all times, but particularly following a cancer diagnosis, adherence to healthful lifestyle behaviors may be one way that older cancer survivors can maintain or regain higher levels of physical functioning while at the same time minimizing risk of recurrence or new malignancy.

Secondary cancer prevention efforts, therefore, become of prime importance in this population. There is a growing body of evidence demonstrating that there are indeed benefits to cancer patients and cancer survivors if they adjust their lifestyles to reflect measures that can prevent future recurrence and the incidence of new cancers. However, it must be noted that in many instances, rising health care costs, minimal health insurance coverage, and reduced economic status impact older patients' access to early detection/screening programs as well as their ability to adhere to healthy lifestyles aimed at prevention of malignancies.


Following Cardiology’s Established Lead

Cardiology has shown oncology the way in providing effective guidelines to increase survival times and decrease the likelihood of a second attack on "good health." It is standard practice for a victim of a heart attack or angina to begin antihypertensive and lipid-lowering medications, tobacco cessation, a "heart-healthy" diet, and an exercise program, trying to make up for what he/she had neglected prior to the initial cardiovascular event. Studies have shown that these measures can be very effective and are, in effect, better late than never. This is known as secondary prevention, and we are learning that it may be equally important in cancer survivors. Just as secondary prevention can do much to prevent subsequent cardiovascular events, these strategies may be integral to staving off cancer recurrence or other diseases for which cancer suriviors are at increased risk.

For example, in general, regular physical activity is consistently associated with higher levels of physical functioning in older adults,(6) and more recently among those who specifically are cancer survivors. A recent review found that older cancer survivors who regularly exercise have more favorable scores in functional status (e.g., improved functional capacity, flexibility and reduced risk of falls); body composition (e.g., preserved lean body mass, reduced body fat, and improved bone mineral density); disease risk (e.g., reduced prevalence of hypertension and hyperlipidemia); and mental health and quality of life (e.g., reduced prevalence of depression and anxiety).(7) Of great interest are the results of another recent study of over 5,000 breast cancer patients that suggests that survivors who exercise at least 3.5 hours a week have significantly higher rates of disease-free and overall survival, thus providing even stronger evidence of the benefits of exercise among cancer survivors.(8)

More limited data exist for other lifestyle factors. However, in a recent cross-sectional study of 688 elderly patients with newly diagnosed breast or prostate cancer, lower dietary fat intakes, increased fruit and vegetable intake, and regular exercise were all significantly and independently associated with improved physical functioning.(9) Indeed, a plant-based diet high in fruits and vegetables and low in saturated fat, coupled with an active lifestyle and the achievement of desirable weight, is the foundation of the American Cancer Society's Guide for Diet and Physical Activity among Cancer Survivors.(10) Therefore, while all cancer survivors may benefit from healthy lifestyle interventions, older cancer survivors may derive particular benefit from interventions aimed at attaining normal weight and those positively influencing functional status, such as routine exercise and increased consumption of fruits and vegetables.

Data suggest, though, that survivors over age 65 may be less likely to adhere to these guidelines at the time of diagnosis and less likely following diagnosis to pursue or maintain healthful changes in lifestyle behaviors.(11) Figure 1 depicts lifestyle characteristics of older versus younger cancer survivors from the FRESH START diet and exercise trial.12 These data suggest that most breast and prostate cancer survivors do not smoke, regardless of age. On the other hand, few practice goal behaviors for exercise (e.g., 30 minutes/day = 5 days a week) and diet (e.g., fruit and vegetable consumption of 7 servings/day for women and 9 servings/day for men). Furthermore, the study suggests that the majority of cancer survivors are overweight or obese (BMI > 25). Although older survivors are significantly more likely than younger survivors to adhere to a low saturated fat diet (< 10% of calories from saturated fat), a significantly higher proportion are overweight or obese. These data derive from a large sample of cancer survivors who demonstrated a willingness to participate in a diet and exercise trial and may therefore be biased. Yet, it must be noted that the percentage of older cancer survivors reporting regular exercise (21.9%) at baseline is similar to the 24.9% observed among older survivors participating in the National Health Interview Study.(13)

Figure 1. Percentages of prostate and breast cancer survivors adhering to guidelines for weight and lifestyle behaviors: younger (n = 486) versus older survivors (n = 192).

** P<0.01
***P<0.001


Oncologists’ Role

Although oncologists clearly are in a key position to promote healthful lifestyle changes, research suggests that less than one quarter of them discuss prevention with their patients.(11) One barrier to providing such guidance has been the relative dearth of evidence-based diet and exercise guidelines for cancer survivors. This, however, is an area where data are rapidly accumulating and where established guides for informed choices now exist.(10) Additional barriers, such as limited time, resources, and expertise in delivering effective lifestyle interventions may be overcome by developing partnerships with allied health personnel (e.g., registered dietitians, exercise physiologists, or nurse practitioners) or with behavioral researchers working to establish effective interventions specifically for these older cancer survivors.(14) Several lifestyles trials are underway, including the RENEW (Reach Out to Enhance Wellness RENEW@geri.duke.edu) trial, which is currently enrolling breast, prostate, and colorectal survivors greater than 65 years of age (five years postdiagnosis), and represents a pioneering effort aimed specifically at improving the long-term health of this population.

Thus in summary, older cancer survivors and older cancer-free individuals represent a rapidly expanding and vulnerable population at risk for several co-morbid conditions and functional decline. Based on current evidence, diet and exercise interventions hold significant potential to improve overall health and to positively reorient trajectories of physical functioning. Similar secondary prevention efforts have become routine in the arsenal of cardiologists in treating their patients with coronary artery disease and myocardial infarction.

Oncologists can play an important role in promoting these healthful lifestyle changes among older patients with cancer. Yet, only 20% provide such guidance.(15) Oncologists can efficiently bring about and considerably impact cancer prevention success in the elderly by partnering with allied health personnel and/or behavioral researchers to facilitate healthy lifestyle changes in this expanding population at high risk and with high levels of need.

References

1. National Cancer Institute Office of Cancer Survivorship. Cancer Control and Population Sciences: Research Findings.
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