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Smoking Cessation, Diet, and Exercise May Influence
Survival in Cancer Survivors
Roxanne Nelson
April 13, 2008 (San Diego) — Smoking, exercise, and diet are
behavioral aspects of health that are of increasing interest,
because they might influence survival and disease risk in cancer
survivors, researchers reported here at the American Association for
Cancer Research 2008 Annual Meeting. The nature and role of health
habits and lifestyle is an emerging area of translational
research.
"One of the opportunities that this meeting provides for us is to
look at some of the more social science research," said Jimmie C.
Holland, MD, Wayne E. Chapman Chair in psychiatric oncology at
Memorial Sloan-Kettering Cancer Center, in New York, New York, who
moderated the forum.
Translational medicine is the continuum often referred to as
"bench to bedside" because it refers to the process of applying
molecular insights from laboratory discovery to clinical care. "The
topics covered in this symposium are of particular interest to
cancer survivors," said Dr. Holland. "We need this interdisciplinary
approach to cancer to provide us with the kind of resources that, in
the long run, are going to serve us best."
There are now more than 10 million cancer survivors in the
United States; from a research standpoint, this represents an
opportunity to study the emotional and long-term management of this
population.
Smoking Cessation
Tobacco remains the most preventable cause of death in the United
States, but many patients diagnosed with cancer continue to smoke.
Although some patients see a cancer diagnosis as an impetus for
quitting, others feel that because they already have cancer, there
is no reason to stop, explained Jamie S. Ostroff, director of the
smoking cessation program at Memorial Sloan-Kettering Cancer
Center.
"Many cancer patients are also older adults, so they may feel
that the damage is done," said Dr. Ostroff. "But it is never too
late to quit and there are many health benefits associated with
quitting. Our patients often know the risks, but we need to be
equally cognizant about the benefits of quitting."
There are many benefits of smoking cessation that are
cancer-specific. Patients who stop smoking have improved survival
and fewer treatment complications, particularly those diagnosed at
an early stage who are undergoing curative resections. However, Dr.
Ostroff pointed out, there are a number of barriers to smoking
cessation in this population. These include heavy nicotine
dependence, withdrawal symptoms, inadequate coping strategies,
treatment factors, and the presence of smokers in the social
network.
Clinicians have a number of opportunities to promote cessation,
such as when the patient transitions from the inpatient to
outpatient setting. "We have to do more than just give them advice,"
she said. "The field has begun to look at rates of smoking cessation
after cancer diagnosis, and it varies tremendously."
To be successful, a comprehensive approach must be taken — one
that will not only educate patients but will also provide them with
referrals and smoking-cessation tools. Staff members might need
training to successfully implement smoking-cessation programs.
"There are promising translational research opportunities in
smoking cessation in cancer patients," Dr. Ostroff. "One is the use
of biomarkers to help us better understand risk profiles and disease
outcomes; we need a more direct measurement of tobacco exposure and
its effect on disease outcome."
Exercise
There is strong interest in the role of exercise in cancer
survivors, but most research has looked at its relation to quality
of life and physical function. But whether or not it has any affect
on disease recurrence or survival is an area of huge interest for
cancer survivors, explained Kerry S. Courneya, PhD, a professor in
the faculty of physical education and department of oncology at the
University of Alberta, in Edmonton.
There have been studies done evaluating the relation between
exercise and cancer incidence, but researchers can't generalize the
results from incidence to recurrence. "We have to be cautious
because the mechanisms of recurrence and incidence may be different,
the effect of exercise may be different after cancer occurs,
effective treatments may trump exercise, and exercise may interact
for better or worse," he said "Cancer survivors may have less time
to benefit from exercise, or they may feel that exercise didn't
prevent them from getting cancer in the first place."
To prove that exercise can alter outcomes in cancer survivors,
the best evidence would be from randomized controlled trials, but
none have yet been conducted. There is some evidence available from
observational trials, however, that exercise might be beneficial in
this population, Dr. Courneya explained.
In 1 observational study that evaluated exercise and cancer
recurrence, physical activity was found to reduce the risk for
breast cancer, after controlling for body mass index and diet.
Exercise can influence treatments and reduce the risk for other
potentially fatal diseases by, for example, helping to control lipid
levels and blood pressure.
"We need good epidemiological research and valid measures, and
complete control of confounders," he said. "Studies need large
samples and long follow-ups. We need objective measures and subgroup
analyses. We need randomized controlled trials with credible
biomarker end points; ultimately, we need randomized controlled
trials with cancer end points."
The first randomized controlled trial looking at exercise as a
cancer end point is going to be launched in Canada. Called the Colon
Health and Life Long Exercise Change Challenge (CHALLENGE), it will
be a multicenter trial with 1000 participants. The researchers are
hoping to open accrual at the end of 2008.
As of right now, observational research is preliminary but
consistent, Dr. Courneya said. "But randomized controlled trials
with disease end points are not available, so no strong comment can
be given at this time."
Diet
"Cancer survivors make up 3% to 4% of the American population,
and that number will probably increase with aging population and
better cure rates," said Wendy Demark-Wahnefried, PhD, from the
University of Texas MD Anderson Cancer Center in Houston. "Cancer
survivors are at greater risk for progressive disease, second
primaries, cardiovascular disease, osteoporosis, and functional
decline. Subsets are prone to depression and fatigue. We need to
treat the whole patient."
There is strong evidence to date about how diet can help prevent
some of the diseases that affect cancer survivors. The American
Cancer Society and the World Cancer Fund both have dietary
guidelines for cancer patients. The guidelines are similar, although
there are variations. Both point to weight control as an important
component, and the World Cancer Fund is more stringent in that
respect, Dr. Demark-Wahnefried explained. "They say to be as lean as
possible without being underweight."
Preliminary studies with animals, some dating back almost 100
years, have shown that energy restriction prolongs lifespan. "These
studies showed that the lifespan in animals is prolonged when they
have tumors and energy was restricted," she said.
It is unknown exactly how adiposity can lead to cancer, although
a number of mechanisms have been hypothesized. "Energy restriction
can have an impact on a host of mechanisms, but we don't know what
they are, and we need more research," she said.
Both sets of guidelines stress consumption of fruits and
vegetables and limit red meat consumption. One study that compared
the typical Western diet with the so-called Prudent (plant based)
diet found that there was almost a doubling of death from all causes
among those who ate the Western diet. But there wasn't anything
specific for cancer, Dr. Demark-Wahnefried said. "Diet composition
is probably more important for comorbidity than for cancer.
When looking at the dietary factors of cancer survivors, 59% to
71% are overweight and only about half eat the recommended number of
servings of fruits and vegetables. Studies have shown that patients
are most interested in diet soon after diagnosis, and that's the
most teachable moment, she explained. "As time goes on, the interest
tends to wane."
American Association for Cancer Research (AACR) 2008 Annual
Meeting. Presented April 12, 2008.
Related Links
Roxanne
Nelson is a staff journalist for Medscape
Hematology-Oncology.
Medscape Medical News 2008. © 2008 Medscape
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