DOI:10.1093/jnci/djt052
Advance Access publication March 14, 2013
© The Author 2013. Published by Oxford University Press. All rights reserved.
For Permissions, please e-mail: [email protected].
Cancer and Beyond: Healthy Lifestyle Choices for
Cancer Survivors
Kathleen Y. Wolin, Graham A. Colditz
Correspondence to: Graham A. Colditz, MD, DrPH, Department of Surgery, Washington University in St Louis, Campus Box 8109, 660 S Euclid Avenue, St.
Louis, MO 63110 (e-mail: [email protected]).
Since the American Cancer Society (ACS) first published its
Nutrition and Physical Activity Guidelines for Cancer survivors
in 2006 (1), much research has explored the potential benefits of
lifestyle choices among cancer survivors. In 2012, ACS published
an update (2), and other organizations have now developed guidelines for cancer survivors (3). The unifying message is that lifestyle
has a major influence for cancer survivors, just as it is essential for
cancer prevention (4). The key dietary recommendations across
these reports are: 1) choose fruits and vegetables; 2) choose whole
grains over refined grains; 3) choose fish and poultry over red and
processed meats; 4) choose unsaturated fats, such as olive oil, over
saturated and trans-fats; and 5) choose low-fat over full-fat dairy.
In addition, recommendations call for the maintenance of a healthy
body weight, regular physical activity, and cessation of smoking
and avoidance of tobacco. Together, these behaviors address the
increased risk for other diseases that many cancer survivors also
experience.
In this issue of the Journal, Kroenke et al. (5) followed 1893
breast cancer survivors a median of 11.8 years, observing that
consumption of more than one serving per day of high-fat dairy
increased all-cause, breast cancer–specific and non–breast cancer
mortality but was not associated with risk of recurrence. No association was observed for low-fat dairy. Overall dairy consumption
was associated with an increased risk of all-cause mortality but was
not related to breast cancer–specific outcomes. This study builds
on previous literature examining dietary fat, dairy, and breast
outcomes, which have had mixed results. In a previous observational study that followed 1982 breast cancer survivors for a mean
13.1 years (6), consumption of two or more servings per day of
dairy was associated with a decreased risk of mortality (86% of
deaths were due to breast cancer), with a statistically significant
trend. That association became non-statistically significant when
adjusting for physical activity, leading the authors to speculate that
high dairy intake reflects good health and not that high intakes
cause it. The study did not separate high- and low-fat dairy. In the
same population, a subsequent analysis observed a healthy dietary
pattern after breast cancer diagnosis was not associated with overall
or breast cancer–specific mortality (7).
Kroenke et al. hypothesize that the effects of dairy on post–
breast cancer outcomes are driven primarily by estrogenic hormones, which reside in fat and are thus more prevalent in high-fat
than low-fat dairy (5). This would also suggest that diets generally high in fat would be associated with breast cancer outcomes.
A high-fat diet was associated with mortality in a previous observational study of breast cancer survivors (8). Two large, randomized
trials, Women’s Healthy Eating and Living (WHEL) and Women’s
Intervention Nutrition Study (WINS), also observed that a low-fat
diet reduced risk of recurrence and mortality in women with breast
jnci.oxfordjournals.org
cancer (9,10). However, the association was strongest for high-fat
dairy and non–breast cancer mortality, suggesting the mechanism
is something other than estrogen.
Taken together, the evidence among breast cancer survivors
supports the importance of a diet that is low in fat, regardless of
the fat source. In the current study (5), a strong correlation (r = .70;
P < .001) between high-fat dairy and saturated fat precluded the
authors from accounting for total fat intake in their analyses of
high-fat dairy. The authors note that their findings are stronger for
dairy and breast cancer outcomes than for saturated fat and breast
cancer outcomes, but these data are not presented. That no association was found for increasing intake of low-fat dairy and only
for increasing intake of high-fat dairy, combined with the existing
literature on dietary fat and mortality in breast cancer survivors,
however, suggests that fat and not dairy, per se, may be the relevant nutritional factor. Although the authors hypothesize that the
dairy effect is driven by estrogens, that the association did not vary
across causes of death suggests that other mechanistic pathways are
equally important in the association of high-fat dairy (or high-fat
diet) and mortality.
The authors’ analytic approach (averaging consumption for
women who survived to the second questionnaire instead of updating exposure level as was done for the study covariables) may have
blunted any exposure effects. It also precluded the authors from
examining whether the timing of exposure might matter. It is well
known that exposure timing, particularly for hormone-associated
factors, is important in breast cancer risk (11).
The study authors note they were limited in their ability to
examine several questions of interest, in part by the low intake of
dairy in this population (mean = 1.7 servings per day). The dairy
intake, however, is consistent with national estimates for women
aged 51 years and older (1.35 servings per day) (12).
The time of the study data collection was one where secular
trends reflect decreasing milk consumption (12,13) and the selection of low-fat dairy over high-fat dairy (14). It was also the time
when the market share of soy and other plant-based milks was
growing rapidly. Thus, it is reasonable to assume that the consumption patterns of the women in the study changed over time.
Ultimately, consumption of high-fat dairy is a small part of the
diet of the women in this study. A recent review suggests that
the benefits of diet and physical activity among survivors may
come largely from maintenance of a healthy weight (15). The
study size did not allow Kroenke et al. to examine associations in
subgroups. Future studies examining dietary associations across
body weight categories are thus important. Furthermore, as other
studies have highlighted the complex relation between dairy and
adverse health outcomes (16), future investigation should continue to distinguish between high- and low-fat dairy in analyses
JNCI | Editorials 593
of diet and outcomes among survivors. Interestingly, women who
consumed the greatest amount of high-fat dairy were more likely
to be physically active, less likely to consume alcohol, had higher
body mass index, and were more likely to have smoked. This suggests that one component of dietary intake cannot be presumed to
represent a broader lifestyle. Examination of interactions among
lifestyle choices and dietary patterns would provide novel information. Regardless, health messages for cancer survivors must be
comprehensive.
Despite the limitations in the study data and analytic approach,
the authors report that consumption of high-fat dairy was associated with elevated risk of all-cause, breast cancer–specific, and noncancer mortality among breast cancer survivors. Understanding
whether the substitution of low-fat dairy for high-fat dairy or use
of plant-based dairy substitutes (eg, almond milk and soy cheese)
improves outcomes remains important for survivors and researchers alike, particularly given the proliferation of these products in
the food market. However, the key message for survivors should
remain the importance of lifestyle in their health—limited not just
to the consumption of a healthy diet but also to the maintenance of
a healthy weight, being physically active, and not smoking.
With the population of cancer survivors, and breast cancer survivors in particular, growing, there is need for clear lifestyle recommendations. The study by Kroenke et al. adds to the robust
literature that healthy lifestyle choices matter for improving odds
of disease-free survival among cancer survivors. Clinicians and survivors should continue to focus on maintaining a healthy weight,
being physically active, avoiding smoking, and choosing a diet
comprised of fruits and vegetables, lean protein, whole grains, and
low-fat foods, including dairy. As with cancer prevention (17), clinicians can employ shared decision making to prioritize the implementation of lifestyle recommendations by patients.
5. Kroenke CH, Kwan ML, Sweeney C, Castillo A, Caan BJ. High- and lowfat dairy intake, recurrence, and maortality after breast cancer diagnosis.
J Natl Cancer Inst. 2013.
6. Holmes M, Hunter D, Colditz G, et al. Association of dietary intake of fat
and fatty acids with risk of breast cancer. JAMA. 1999;281(10):914–920.
7.Kroenke CH, Fung TT, Hu FB, Holmes MD. Dietary patterns and survival after breast cancer diagnosis. J Clin Oncol. 2005;23(36):9295–9303.
8. Beasley JM, Newcomb PA, Trentham-Dietz A, et al. Post-diagnosis dietary
factors and survival after invasive breast cancer. Breast Cancer Res Treat.
2011;128(1)229–236.
9.Chlebowski RT, Blackburn GL, Thomson CA, et al. Dietary fat reduction and breast cancer outcome: interim efficacy results from the Women’s
Intervention Nutrition Study. J Natl Cancer Inst. 2006;98(24):1767–1776.
10.Pierce JP, Natarajan L, Caan BJ, et al. Influence of a diet very high in
vegetables, fruit, and fiber and low in fat on prognosis following treatment
for breast cancer: the Women’s Healthy Eating and Living (WHEL) randomized trial. JAMA. 2007;298(3):289–298.
11.Bernstein L. Exercise and breast cancer prevention. Curr Oncol Rep.
2009;11(6):490–496.
12.Sebastian RS GJ, Enns CW, LaComb RP. Fluid Milk Consumption in the
United States. http://www.ars.usda.gov/SP2UserFiles/Place/12355000/
pdf/DBrief/3_milk_consumption_0506.pdf. Accessed February 21, 2013.
13.Briefel RR, Johnson CL. Secular trends in dietary intake in the United
States. Annu Rev Nutr. 2004;24:401–431.
14. Wells H, Buzby J. Dietary Assessment of Major Trends in US Food Consumption,
1970–2005. Washington, DC: US Department of Agriculture, Economic
Research Service; 2008.
15. Davies NJ, Batehup L, Thomas R. The role of diet and physical activity in
breast, colorectal, and prostate cancer survivorship: a review of the literature. Br J Cancer. 2011;105(Suppl 1):S52–S73.
16. Beydoun MA, Gary TL, Caballero BH, Lawrence RS, Cheskin LJ, Wang
Y. Ethnic differences in dairy and related nutrient consumption among US
adults and their association with obesity, central obesity, and the metabolic
syndrome. Am J Clin Nutr. 2008;87(6):1914–1925.
17. Politi MC, Wolin KY, Legare F. Implementing clinical practice guidelines
about health promotion and disease prevention through shared decision
making [published online ahead of print January 12, 2013]. J Gen Intern
Med. 2013. doi: 10.1007/s11606-012-2321-0.
References
Funding
1.Doyle C, Kushi LH, Byers T, et al. Nutrition and physical activity during and after cancer treatment: an American Cancer Society guide for
informed choices. CA Cancer J Clin. 2006;56(6):323–353.
2.Rock CL, Doyle C, Demark-Wahnefried W, et al. Nutrition and
physical activity guidelines for cancer survivors. CA Cancer J Clin.
2012;62(4):243–274.
3. Schmitz KH, Courneya KS, Matthews C, et al. American College of Sports
Medicine roundtable on exercise guidelines for cancer survivors. Med Sci
Sports Exerc. 2010;42(7):1409–1426.
4. Colditz GA, Wolin KY, Gehlert S. Applying what we know to accelerate
cancer prevention. Sci Transl Med. 2012;4(127):127rv4.
594 Editorials | JNCI
This work was supported by a grant from the National Cancer Institute
(P30CA091842) and the Foundation for Barnes-Jewish Hospital. GAC is supported by an ACS Clinical Research Professorship.
Note
The funder had no role in the writing of this editorial or the decision to submit it
for publication. The authors have no conflicts of interest to disclose.
Affiliation of authors: Department of Surgery, Alvin J. Siteman Cancer
Center and Division of Public Health Sciences, Washington University School
of Medicine, St. Louis, MO (KYW, GAC).
Vol. 105, Issue 9 | May 1, 2013