By Andrea M. Pampaloni, Ph.D.
The link between obesity and cancer is well-established. Attributable to anthropometric and lifestyle factors, people with obesity often have comorbidities and other conditions that predispose them to cancer. As the rate of obesity continues to rise, so does the number of obesity-related cancers. Despite a 25-year low in the number of cancer deaths in the United States, the number of cancer deaths related to obesity is growing.1 Obesity is second only to tobacco as the leading cause of cancer.2 Even this is likely to change over the next couple of decades as obesity rates rise and fewer smoke. The Cancer Research UK similarly forecasts that obesity will “be linked with more female deaths than smoking” due to the United Kingdom’s similar trends in obesity and smoking.3
The World Cancer Research Fund and American Institute for Cancer Research found strong evidence that patients with obesity or are overweight throughout adulthood increases the risk of multiple types of cancer, including esophageal, pancreatic, liver, colorectal, endometrial, kidney, and breast (in postmenopausal women).4 Further, patients with obesity or are overweight have an increased risk for other cancers, including gallbladder,5 liver, multiple myeloma, non-Hodgkin’s lymphoma, cervical,6 ovarian, stomach, and mouth, pharynx and larynx.7
After treatment, patients with obesity still face greater challenges. They have worse prognoses, an increased risk of metastatic disease, and shorter remission periods.8 There also are indications that cancer survival rates decrease for patients with obesity depending on the type of cancer.9 This has been found in cases of breast, endometrial, prostate pancreatic, colorectal, and ovarian cancers.10 Among cancer survivors, patients with obesity report lower physical and functional well-being, poorer quality of life, and fatigue.11,12
CHALLENGE: CANCER AND WOMEN WITH OBESITY
Cancer risk for women is high. Women with obesity are more likely than men and other women of healthy weight to have cancer. Women receive 55 percent of cancers diagnoses13 and seven14 to 20 percent15 of cancer deaths in women are linked to overweight or obesity. Indeed, these estimates may be conservative factoring in the continued upward trend in obesity since this research was conducted.16
Breast cancer is the most common type of cancer in women and the connection between obesity and breast cancer is strong. The likelihood of a women with obesity getting cancer is affected specifically by a women’s weight prior to and after menopause. Premenopausal women who are overweight or were overweight between the ages of 18 and 30 have lower rates of breast cancer17 and women who lose weight after menopause also reduce the risk for breast cancer.18 Conversely, women who are overweight, or gain weight in adulthood have a higher risk of postmenopausal breast cancer.19 Even a slight weight gain increases the risk of getting breast cancer. Healthy women who gain five percent of their body mass over a decade increased their risk by 36 percent,
about the same risk experienced by obese women (BMI>30 kg/m2). Women with morbid obesity (BMI>35 kg/m2) are at an even higher risk (58%) of developing an invasive breast tumor and experience lower survival rates.20
The risk for women extends beyond breast cancer. A longitudinal study that assessed the impact of weight duration on cancer in postmenopausal women revealed a significant connection between longer durations of being overweight (BMI>25 kg/m2) or obese (BMI ≥ 30 kg/m2) and colon, endometrial, and kidney cancers, in addition to breast cancer.21
Despite the prevalence of obesity in the population, most Americans are unaware of the connection between
obesity and cancer.22 This suggests that greater education and awareness can make a strong, impactful
difference and lead to a decrease in obesity and, correspondingly, the likelihood of cancer. Weight loss is by far
the best corrective measure.
SOLUTION: WEIGHT LOSS BENEFITS & CANCER
Although specific dietary components are not directly linked to a greater or lesser likelihood of cancer, excessive
weight is clearly linked with greater risks. Several studies state that a moderate five to 10 percent reduction in
body weight positively impacts health outcomes for patients with obesity.23,24 There also is strong consensus
among researchers and health care providers that weight loss and avoiding weight gain as an adult are
beneficial in virtually all cases of obesity.
Evidential research validating weight loss as a means of cancer prevention is limited for two reasons. First,
weight loss findings typically are self-reported rather than measured and thus may not be reliable; also, it is
not always possible to determine whether weight loss is or is not intentional. However, studies that use a more
rigorous approach to linking weight loss to cancer occurrences have found a link. For example, postmenopausal
women who lost roughly five percent of their body weight had a lower risk of breast cancer than women who
did not lose weight.25 Luo and colleagues likewise found that intentional weight loss lowered women’s risk for
endometrial cancer.26 Improvements to cardiovascular health, systolic and diastolic blood pressure, and HDL
cholesterol resulting from weight loss also benefit patients throughout and following treatment.
An increased awareness by doctors and health care providers on the importance of addressing obesity with
patients – combined with advances in technology – offer multiple options for weight loss interventions.
To achieve meaningful weight loss, lifestyle changes must be adopted, including a reduction in caloric
intake. Caloric reduction helps reduce inflammation which is common in patients with obesity and
leads to chronic disease.27 The Academy of Nutrition and Dietetics notes that the effectiveness of
dietary approaches varies among individuals. As such, it supports the use of different, evidence-based
interventions, including Low Calorie Diets (LCD), Very Low Calorie Diets (VLCD), and meal replacement or
structured meal plans based on individual need and preferences.28
LCD and VLCD programs are effective approaches to weight loss with the benefit of improved metabolic
parameters. In studies using meal replacement plans, significant improvements in body weight, BMI,
blood glucose, and blood pressure were found,29 as was reduced joint pain, greater energy, and
improved mental health.30 These improvements help minimize participants’ risk not only of cancer, but
also cardiovascular disease and diabetes.31 Adults following meal replacement plans also maintained
their weight loss after a year,32 contrary to previously held views that rapid weight loss is followed by
rapid weight gain.
Exercise, in combination with diet, results in the greatest weight loss.33 Physical activity offers significant
improvements in cardiometabolic health and has been shown to improve outcomes for breast and
colon cancer patients. The American Heart Association recommends 150 minutes per week of moderate
intensity or 75 minutes per week of vigorous intensity. Individuals new to an exercise regime do better
starting with shorter sessions throughout the week, then increasing them 10 percent per week until the
targeted level is achieved.34
Counselling and Support
Having a support system during weight loss is vital to commitment and effectiveness. In a study of
participants with obesity following an LCD, support systems were credited with helping 80 percent of
participants meet or exceed their 10 percent weight loss goal.35 Group meetings are effective structures
for support, though those who struggle with weight loss or desire more intensive counselling may benefit
from individual sessions with a behavioral psychologist or registered dietician. Both group and individual
counselling have been found effective in achieving significant weight loss, BMI reduction, and waist
In addition to traditional face-to-face sessions, advances in technology offer multiple options to
accommodate the preferences of virtually any patient. For example, using a phone-based intervention,
women being treated for breast cancer lost significantly more weight than the comparison group.37
Another study using behavioral interventions including either face-to-face or remote contact revealed
significant weight loss for all participants which they maintained for two-years.38 The VITAL study similarly
found video conferencing can be effective and convenient for weight management.39
Self-monitoring, such as tracking one’s diet, also is associated with weight loss. Diligence in tracking food
daily results in the greatest weight and likelihood of keeping it off.40 A meta-analysis found that compared
to other interventions, mobile phone apps led to significant loss of weigh and reduction in BMI, with
additional improvement in physical activity.41 With the vast majority of Americans owning a smartphone
the use of weight loss and tracking apps offer opportunities previously unavailable to enhance and
improve the weight loss experience.
These findings suggest that to minimize the risk for several types of cancer, women should maintain a healthy
weight with a BMI of 25 kg/m2 or lower. Because most Americans are unaware that obesity increases the risk
for cancer, doctors and health care providers must be proactive in addressing obesity with their patients.
Traditionally the purview of primary care physicians (PCP), a more comprehensive, team-based approach to
weight loss is necessary to help patients identify and resolve obesity-related diseases, including cancer.
Weight loss as an intervention to reduce the risks of cancer involves multiple levels. Reducing caloric intake,
specifically through a LCD or VLCD, and increasing physical activity, are among the most effective steps a patient
with obesity can take to ensure better health outcomes.
Because patients with obesity already face more health complications than healthy-weight individuals, a multidisciplinary team, including PCPs, nurses, registered dieticians, oncologists, surgeons, behavioral therapists,
and other relevant healthcare professionals, must come together to recommend interventions appropriate
and specific to patients’ needs.42 Although the Centers for Disease Control recommends that health care
providers counsel patients with obesity on the connection between weight and cancer,43 patients report that
their oncologists rarely counsel them about weight loss.44 Everyone involved in patient care must take a role in
educating patients and their publics about the high risks of obesity.
The number of American adults with obesity has risen significantly since 2000, from just over 30 percent to
nearly 40 percent. At this rate, by 2030 more than half of the adults in the United States will have obesity45 and
there will be over a half-million new obesity-related cases of cancer each year.46 It is not unreasonable to believe
that the ability to effectively provide medical, emotional, social, and financial support will, at some point,
The single most effective means of reducing the number of cancer cases is to create a healthier, lower-weight
population. It is time for the medical community to adhere to the same recommendations they offer; that is,
a reduction of obesity by five to 10 percent among the patients and populations they serve. Meeting this goal
would significantly reduce the level of obesity and the associated negative health risks.
1 Associated Press. (2019, January 8). U.S. cancer death rate hits milestone of 25 years of decline. NBC News.
2 World Cancer Research Fund, & American Institute. (2018). Body fatness & weight gain and the risk of cancer. World Cancer Fund Research Network.
3 Picheta, R. (2018, September 24). Obesity to become leading cause of cancer in women. CNN.
4 World Cancer Research Fund, & American Institute
5 World Cancer Research Fund, & American Institute
6 American Cancer Society. (2019). Does body weight affect cancer risk?
7 World Cancer Research Fund, & American Institute
8 DePergola, G., & Silvestris, F. (2013). Obesity as a major risk factor for cancer. Journal of Obesity.
9 Parekh, N., Chandran, U., & Bandera, E.V., (2012). Obesity in cancer survival. Annual Review of Nutrition.
10 Barbor, M. (2018, May 10). Obesity in cancer survivors: Identifying teachable moments. The ASCO Post.
11 Schmitz, K.H., Neuhouser, M.L., Collins, T.A., Zanetti, K.A., Bertram, L.C., Dean, L.T., & Drake, B.F. (2013). Impact of obesity on cancer survivorship and
the potential relevance of race and ethnicity. JNCI: Journal of the National Cancer Institute.
12 Schmitz, et al.
13 Centers for Disease Control. (2017, October 3). Cancers associated with overweight and obesity make up 40 percent of cancers diagnosed in the United
14 American Cancer Society
15 World Cancer Research Fund, & American Institute
16 Wolin, K.Y., Carson, K., & Colditz, G.A. (2010). Obesity and cancer. The Oncologist.
17 World Cancer Research Fund, & American Institute
18 World Cancer Research Fund, & American Institute
19 World Cancer Research Fund, & American Institute
20 Neuhouser, M.L., Aragaki, A.K., & Prentice, R.L. (2015). Overweight, obesity, and postmenopausal invasive breast cancer risk. JAMA Oncology.
21 Arnold, M., Jiang, L., Stefanick, M.L., Johnson, K.C., Lane, D.S., LeBlanc, E.S., & Prentice, R. (2016). Duration of adulthood overweight, obesity, and cancer
risk in the women’s health initiative: A longitudinal study. PLOS: Medicine.
22 American Society of Clinical Oncology. (2017, October 24). National survey reveals most Americans are unaware of key cancer risk factors.
23 Dockrill, P. (2016, February 23). The first 5% of weight loss offers the greatest health benefits in obese people, study finds. Science Alert.
24 Wing, R.R., Lang, W., Wadden, T.A., Safford, M., Knowler, W.C., Bertoni, A.G., Hill, J.O., Brancati, F.L, Peters, A., Wagenknecht, L., & Look AHEAD
Research Group. ( 2011). Benefits of modest weight loss in improving cardiovascular risk factors in overweight and obese individuals with type 2 diabetes.
25 BreastCancer.org. (2017, December 16). Overweight postmenopausal women who lose modest amount of weight have lower breast cancer risk.
26 Luo, J., Hendryx, M., & Chlebowski, R.T. ( 2017). Intentional weight loss and cancer risk. Oncotarget.
27 Ye, J., & Keller, J.N. ( 2010). Regulation of energy metabolism by inflammation: A feedback response in obesity and calorie restriction. Aging.
28 Raynor, H.A., & Champagne, C.M. (2016). Position of the Academy of Nutrition and Dietetics: Interventions for the treatment of overweight and obesity in
adults. Academy of Nutrition and Dietetics.
29 Guo, X., Xu, Y., He, H., Cai, H., Zhang, J., Li, Y., Yan, X., et al. (2018). Effects of a meal replacement on body composition and metabolic parameters among
subjects with overweight or obesity. Journal of Obesity.
30 Joy, K. (2018, January 12). Study: Weight loss reduces pain far beyond load-bearing joints. Michigan Medicine M Health Lab.
31 University of Southern California. 2017, February 16). Scientifically-designed fasting diet lowers risks for major diseases. Science Daily.
32 Dorking, M.C. (2018, September 27). Tackle obesity with low-calories shakes and soup diets, say researchers. Yahoo!
33 Raynor & Champagne
800.222.9201 | www.Robard.com
PAMPALONI – 5
34 Fitzpatrick, S.L., Wischenka, D., Appelhans, B.M., Pbert,L., Wang, M., Wilson, D.K., & Pagoto, S.L. (2016). An evidence-based guide for obesity treatment
in primary care. The American Journal of Medicine.
36 Phimarn, W., Paktipat, P., Pansiri, K., Klabklang, P., Duangjanchot, P., & Tongkul, A. (2017). Effect of weight control counselling in overweight and obese young
adults. Indian Journal of Pharmaceutical Sciences.
37 Goodwin, P.J., Segal, R.J., Vallis, M., Ligibel, J.A., Pond, G.R., Robidoux, A., Blackburn, G.L., et al. ( 2014). Randomized trial of a telephone-based weight
loss intervention in postmenopausal women with beast cancer receiving letrozole: The LISA trial. Journal of Clinical Oncology.
38 Appel, L.J., Clark, J.M., Yeh, H.C., Wang, N.Y., Coughlin, J.W., Daumit, G. Miler, E.R., et al. (2011). Comparative Effectiveness of weight-loss interventions in
clinical practice. The New England Journal of Medicine.
39 Azar, K.M.J., Aurora, J., Wang, E.J., Muzzaffar, A., Pressman, A., & Palaniappan, L.P. (2014). Virtual small groups for weight management: An innovative
delivery mechanism for evidence-based lifestyle interventions among obese men. Translational Behavioral Medicine.
40 Patel, M.L., Hopkins, C.M., Brooks, T.L., & Bennett, G.G. (2019). Comparing self-monitoring strategies for weight loss in a smartphone app: Randomized
controlled trial. JMIR Mhealth Uhealth.
41 Mateo, G.F., Font, E.G., Grau, C.F., & Carreras, X.M. ( 2017). Mobile phone apps to promote weight loss and increase physical activity: A systematic review and
meta-analysis. Journal of Medical Internet Research.
42 Raynor & Champagne
43 Centers for Disease Control
45 Begley, S. (2012, September 18). Fat and getting fatter: U.S. obesity rates to soar. Reuters.
46 Bertagnolli, M.M. (2019, February 4). New findings on obesity and cancer. ASCO Connection.