Page 23 - Today's Dietitian (February 2020)

Alcohol Drinking
Alcohol in moderation has been associated with reduced
CVD risk in observational studies, although without data
from randomized controlled trials. However, this occurs in a
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well-documented “J-shaped dose-effect curve,” with excessive
alcohol leading to elevated triglycerides, hypertension,
cardiomyopathy, increased cardiovascular events, and all-
cause mortality. 5,8,20 Evidence shows a causal relationship
between alcohol and risk of several cancers. 5,8,21 This may
involve the genotoxic effect of acetaldehyde (the primary
metabolite of alcohol), oxidative stress, increased estrogen
levels, effects on folate metabolism (needed for healthy DNA),
and alcohol’s ability to serve as a solvent for carcinogens.
Increase in cancer risk is most substantial when consumption
is beyond moderation (defined as up to one standard drink
per day for women and two per day for men). However, even
light drinking of up to one drink per day poses some increase
in women’s risk of breast cancer and in risk of esophageal
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and oropharyngeal cancers. (See “Alcohol Consumption and
Cancer Risk — The Other Side of a Health Halo,” in the April
2018 issue of Today’s Dietitian.)
Although alcohol is a well-established risk factor for the
Hypertension development of certain cancers, it’s unclear how postdiagnosis
Hypertension is another major established CVD risk factor. alcohol use affects cancer treatment and long-term survival.
It causes structural changes in blood vessels and the heart, One systematic review and meta-analysis shows increased
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which can lead to heart failure, and induces oxidative stress cancer recurrence, but no association with overall mortality.
that promotes atherosclerosis. Increased oxidative stress also As for prevention, cancer survivors are advised to limit alcohol
contributes to increased cancer risk, and, by increasing vascu- to no more than one drink per day for women or two per day
9,23
lar endothelial growth factor (VEGF), it may potentiate devel- for men. The National Comprehensive Cancer Network clini-
opment or progression of cancer. 8 cal practice guidelines recommend survivors of liver, esopha-
VEGF signaling pathway inhibitor treatments are used for a geal, kidney, and head and neck cancers abstain from alcohol. 9
variety of advanced or metastasized cancers. They block angio-
genesis (growth of blood vessels) that supports tumor growth Cardio-Oncology Rehabilitation
but also can cause or increase hypertension, which indicates Cardiac rehabilitation (CR) programs aim to increase cardio-
success in targeting cancer-blocking effects in blood vessels. 6 respiratory fitness, decrease anginal symptoms, improve
However, these elevations in blood pressure, whether new or psychosocial well-being, and reduce CVD-related morbid-
from destabilization of previously controlled hypertension, ity, recurrent hospitalizations, and mortality. These multi-
can lead to heart failure and other forms of CVD, so current disciplinary efforts provide medical evaluation, prescriptive
reviews emphasize maintaining blood pressure control. exercise, education, and counseling and behavioral interven-
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tions to modify CVD risk factors. CR has been demonstrated
Obesity to reduce CVD mortality and improve health-related quality
Obesity increases CVD risk by acting through major risk fac- of life, and referral to CR is a recognized recommendation for
tors (eg, type 2 diabetes and hypertension) and possibly people with acute coronary syndromes. In 2019, the American
through atherogenic dyslipidemia and emerging risk factors Heart Association issued a scientific statement proposing a
such as insulin resistance, a proinflammatory state, a pro- cardio-oncology rehabilitation (CORE) model to adapt the mul-
thrombotic state, and sleep apnea commonly found in people timodality approach of CR (with exercise, nutrition counseling,
with obesity. Obesity also increases metabolic demands of tobacco cessation interventions, and risk factor assessment) to
cardiac output, requiring increased stroke volume, which can decrease CVD events in cancer survivors at highest CVD risk.
lead to increased left ventricular filling pressure and volume The scientific statement emphasizes that for CORE program
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overload. Cancer risk due to excess adiposity seems related effectiveness, CR program staff must be equipped to address
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to many of the same conditions, such as inflammation and both CVD- and cancer-related concerns, including nutrition.
insulin resistance, as well as increased estrogen production
in postmenopausal women. Although most research on body Exercise Training
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fat’s link to chronic disease has used BMI as a marker of over- Exercise training is the cornerstone of CR and is proven to
weight and obesity, this doesn’t address the complexity of body improve cardiorespiratory fitness and reduce CVD symptoms
composition or adipose tissue. Dysfunctional adipose tissue, in people with established CVD. Although more research is
which is characteristic of most, but not all, people with over- needed, controlled intervention trials in a variety of cancer
weight and obesity, is centrally involved in development of the populations show that exercise after cancer treatment is gen-
metabolic disturbances that promote CVD and obesity-related erally safe and may lessen typical declines in cardiorespiratory
cancers and obesity-associated increased mortality rates. 18,19 fitness and muscle strength; reduce fatigue, anxiety, depressive
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