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Childhood Obesity Can Be a Risk Factor for Colorectal Cancer in Adulthood

Childhood obesity is a significant global public health concern that has escalated since the late 20th century. In 2022, an estimated 37 million children under the age of 5 were overweight and over 390 million children and adolescents aged 5-19 were also overweight, of which 160 million were obese. Significant research has identified the association between obesity and increased cancer risk, including a study that has specifically found a correlation between high early-life body-mass index (BMI) and an increased risk of colorectal cancer (CRC) in adulthood.

 Obesity can have detrimental effects on nearly every organ in a child’s body. The CDC reports that approximately 14.7 million children and adolescents in the U.S. were obese during the period 2017-2020.

Risk Factors of Childhood Obesity

Childhood obesity is a condition in which a child has a significantly higher weight than what is typically expected for their age and height within a specific age range. Since children are continuously growing, the ranges of height, weight, and BMI vary based on age and sex-specific percentiles rather than the BMI cut-points used in adults. However, severe obesity in children can be classified into two classes:

– Class 2 obesity: BMI range between >120% to <140% of the 95th percentile for BMI >35 kg/m2 to <40 kg/m2, based on age and sex.
– Class 3 obesity: BMI >140% of the 95th percentile or BMI >40 kg/m2, based on age and sex.

Several risk factors may contribute to childhood obesity, including:

 1. Genetic factors: Both common and rare genetic variants that affect gene expression or function can contribute to obesity. Genetic factors are considered responsible for 40% to 70% of an individual’s obesity risk.

2. Diet: Young people are more likely to consume fast food, processed snacks, and foods rich in processed sugar. These foods often contain higher levels of carcinogens and mutagens, as well as being high in calorie count. California has taken measures to ban four additives commonly used in foods, particularly snacks for children, that have a strong correlation with cancer: brominated vegetable oil, potassium bromate, propylparaben, and Red dye 3. 

3. Sedentary lifestyle: Play is a crucial aspect of child development, affecting physical, mental, and social development. The prevalence of video games and the virtual world among children and adolescents has led to a decrease in outdoor play. A study found that over 90% of children over 2 years old play video games, with many spending 1.5 to 2 hours per day gaming. This can contribute to health problems, including obesity.

CRC and Obesity 

 A meta-analysis study in the U.S. involving over 4.7 million participants (3.2 million men and 1.5 million women) found that individuals who were obese in their early life had an increased risk of CRC as adults. The study demonstrated a 39% increase in CRC risk for obese males in early-life and a 19% increase for obese females in early-life, compared to controls. For men, an obese BMI in early life was more strongly associated with distal colon and rectal cancer. In women, the association was stronger for rectal cancer. 

Additional studies are needed to fully understand the association between early childhood obesity and CRC risk to prevent cancer in adulthood.

 

Emmanuel Olaniyan is a Colorectal Cancer Prevention Intern with the Colon Cancer Foundation.

Image by kalhh from Pixabay

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Disease-Free Survival: How Does Exercising Impact Colon Cancer?

By Parker Lynch

We all know that exercise is healthy. However, the extent to which a patient with colon cancer could improve their prognosis through exercising is something that was previously unknown, and is still being researched. Authors of one such research study published their findings after analyzing how physical activity impacted individuals with Stage III colon cancer.

Does Exercise Improve Colon Cancer Outcomes?

In collaboration with the National Cancer Institute, two groups of patients with Stage III colon cancer (one of them being a placebo or control group) were randomly assigned to various community and academic centers throughout the U.S. and Canada to be evaluated during the duration of their treatment. Patients were then instructed to report the average weekly time that they spent exercising.                                                                                                                                                                                                                                                                       

Each physical activity was assigned a specific metabolic equivalent (MET). The MET values were then multiplied by the hours that each patient reported spending each week, which were then categorized as:

  • <6 METs (light- to moderate-intensity physical activities) 
  • ≥6 METs (vigorous-intensity activities) 

Patients’ METs were evaluated throughout their chemotherapy treatments as well as six months after treatment completion. 

Here’s What They Found

During a median follow-up of 5.9 years, the study found the following relation between the status of a patient’s health and their corresponding physical activity levels: 

  • For light-intensity to moderate-intensity activities, the 3-year disease-free survival (DFS) was 65.7% with 0.0 hour/wk
  • For vigorous-intensity activity, the 3-year DFS was 76.0% with 0.0 h/wk and 86.0% with ≥ 1.0 h/wk

These results strongly indicate that more frequent, high-intensity recreational activities can improve DFS.

Implications for Patients 

Nothing is ever directly causational, and there are never guarantees that one specific lifestyle change will influence treatment outcome. However, studies like this are vital because they provide information that could change one’s quality of life while going through cancer treatment. If a patient with colorectal cancer picks up running as a new hobby because of this study and it makes them feel better in their day-to-day life, then that is a real-world influence of research studies. 

 

Parker Lynch is a Colorectal Cancer Prevention Intern with the Colon Cancer Foundation.

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Enhancing Colorectal Cancer Prevention with Diet: Molecular Pathways and Improved Outcomes

Nutrition & Colorectal Cancer Prevention Series: Blog 1

The link between nutrition and colorectal cancer (CRC)  prevention is well established. Researchers have found that low-inflammation diets, such as Mediterranean diets, are associated with lower risk of CRC. This study also affirmed the link between sugar intake and CRC risk, with individuals who consume beverages high in sugar being more likely to develop rectal adenomas. 

Other studies have explored the links between highly processed foods and development of colorectal adenomas. In addition to highly processed foods, canned foods have also been shown to increase risk of colorectal polyps when measured against fresh fruits and vegetables.

These associations provide evidence that a low-inflammation diet that is low in sugar and processed foods can lower the risk of developing CRC; however, there is limited research on the impact of nutritional interventions on those who are already diagnosed. 

Can Dietary Interventions Improve CRC Outcomes?

A study published earlier this year explored the answers to that very question. 

In accordance with previous research, the authors found that the Mediterranean diet was effective in reducing CRC tumor growth. The mechanisms that are responsible for this inhibited tumor cell growth include the presence of beta-carotene, which is found in a number of fruits, vegetables, and fish. When beta-carotene interacts with fibroblast activation markers, the fibroblasts repress tumor cell growth in the colon. 

Additionally, anti-inflammatory diets can suppress the growth of CRC tumors via immune system pathways. Tea polyphenols, most commonly found in green tea, add diversity to the gut microbiota by often raising short-chain amino acid levels, which in turn promotes the growth of anti-inflammatory gut bacteria. Elevated levels of these “good bacteria” help to modulate the environment within which CRC develops, and aid the immune system in preventing tumor cell growth and spread.

While it is important to understand these pathways, successful, consistent implementation of preventative diets is the key to unlocking the benefits that come from the pathways. The chart below, adapted from this study, provides a framework for workable diet and lifestyle interventions during the various stages of colorectal cancer treatment, from diagnosis to surgery. Key elements of these interventions involve exercise, protein intake, and supplementation of key nutrients such as omega-3 fatty acids. 

 

Blog 2 in this series can be found here: Tackling Fresh Food Inequality.

Emma Edwards is a Colorectal Cancer Prevention Intern with the Colon Cancer Foundation.

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The Insider Scoop: Unveiling the Relationship Between Exercise and Colorectal Cancer Risk

Photo credit: Arek Adeoye on Unsplash

After publishing a blog post on Sarah Keadle, Ph.D.’s latest published research, entitled “Impact of Moderate-Vigorous Physical Activity Trajectories on Colon Cancer Risk over the Adult Life Course”, I had the opportunity to sit down and chat with her about these findings and what they mean for colorectal cancer prevention. Dr. Keadle holds graduate degrees from the University of Massachusetts Amherst and Harvard University and is Associate Professor, California Polytechnic State University, San Luis Obispo. 

CCF: What were your greatest revelations over the course of this research?

Dr. Keadle: The take home message is pretty consistent with what we see in terms of other physical activity in relation to other disease outcomes, that even moderate amounts of activity are really important. 

In our sample, the moderate group was doing about two hours a week of predominantly walking-type activities, and they were protected. Those who maintain that amount of activity over the life course were protected against colon cancer risk. 

Those who did a little more activity had a little bit more protection, so they were classified as the “high” active. These individuals were exceeding our current physical activity recommendations consistently throughout the life course relative to those who stayed inactive.

But then I think what’s also interesting is that there’s this: we were able to look at those who increased and those who decreased activity over time. The group who decreased their activity, the “early decreasers”, were in the 30-35- age group and had the worst risk—their risk of developing colon cancer was greater than those who stayed inactive. 

And those who were not active when younger but started increasing their activity by age 30, there was evidence suggesting that they may also be protected from developing colon cancer. So if you’re targeting middle-aged adults, it’s not too late to start being active. Even a moderate amount of activity appears to be protective.

                     Sarah Keadle, Ph.D.

CCF: What kinds of exercises would you recommend for people who have mobility issues and are limited in what activities they can do? 

Dr. Keadle: Much  of the data show that walking is the most accessible, and the best form of activity for most adults. For those with more serious limitations that don’t allow them to walk, there could be adaptations such as specialized gym equipment. But I think, for the vast majority of adults, if they feel intimidated by the thought of exercising or running, or exercise that will place a lot of stress on joints, or cause them pain or discomfort, you don’t have to be out of breath and sweating and uncomfortable to get the benefits of physical activity. There’s a lot of evidence that just moderate walking is one of the best forms of activity. 

As part of the 2018 physical activity guidelines, [the Department of Health and Human Services] launched the Move Your Way campaign to try to promote physical activity at the community level, and I know that they have several resources on how to adapt things to people with different types of disabilities. 

CCF: My next question is more about structural barriers to exercise. So people who are living in locations where they don’t really have access to safe parks and gyms. What would you recommend?

Dr. Keadle: That is a huge issue. I think one benefit potentially of COVID is that there are more online resources for at home activities and workouts that are targeted at different levels and different types of activities. So I think that’s a good place to start. It’s also important to spread the message of just getting up and moving, trying to not sit for really long periods of time. Get up and move around your house or try to find places that feel safe, even if it’s the backyard. To get outside and try to break up and get steps in is definitely beneficial. 

CCF: Those are great tips. And what kinds of policy changes, if any do you think would help alleviate some of those barriers?

Dr. Keadle: That’s a great question. So the CDC [Centers for Disease Control and Prevention] has launched a campaign around safe streets and complete streets programs to try to make it so that our streets are safer for people to bike, walk, and drive. I’m teaching a class right now on physical activity and public health to undergraduate students, and they ask, “We’ve reviewed the evidence. Physical activity is good. But, what are we actually doing about it?” And I think that the Move Your Way campaign has done a good job of trying to get more community level buy-in. And that’s one of the big things that needs to happen to kind of shift the culture around physical activity. 

I think that there are things happening, but it’s definitely slow, and I think aligning physical activity with other goals is important. So, if you have an activity program in a park that may make the park safer and in the long run, you also have the benefit of increasing physical activity. 

However, there’s not a lot of money in promoting physical activity. There’s no lobby group that will make money off of promoting physical activity. So, hopefully, we can capitalize on other initiatives and try to convince people to create those types of structural changes. Access to green space is a big predictor of physical activity, so making safe parks available is one of the biggest policy level changes I can think of. 

CCF: Yeah, well thank you so much. Lastly, I just want to say congrats again on the publication of the study back in January. That’s amazing. And what is next for you and your team in terms of either just exercise research or colon cancer research? 

Dr. Keadle: I have an intervention study for which we’re randomizing our last subject. The study is looking at a strategy to try to reduce screen time in adults. There’s a fair amount of data on kids, but we don’t know a lot about adults in terms of what’s the best way to get people off their screens. And if they do, are they more physically active? And what else changes along with that? 

I’m also continuing to do a few epidemiological studies about the interaction between physical activity and sedentary time and how that relates to health. It’s interesting because people cite lack of time as their biggest barrier to being physically inactive—it is the most commonly cited barrier. But then, if you look at the actual time-use data, people are spending like four hours a day on their phones.

So it’s perceived, and I get it that not everybody wants to exercise in the evening. But that’s where that messaging of “move more, sit less, break up sedentary time” and trying to make it approachable and just beginning to get it into people’s lifestyle is going to end up being a huge change in the long run. 

CCF: Absolutely, yeah. And maybe even communicating those messages through social media.

Dr. Keadle: Right. We have an app for our study, which feels ironic, that we’re trying to reduce screen time by creating an app that tracks their screen time and gives them feedback and strategies, but it lets [participants] set limits and things like that.

 

Emma Edwards is a Colorectal Cancer Prevention Intern with the Colon Cancer Foundation.

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Fitness and Reducing Colon Cancer Risk: It’s Never Too Late to Start!

The benefits of exercise for overall health and disease prevention are well known. While research overwhelmingly points to physical activity as a protective factor against colorectal cancer, more research is necessary to delineate how the timing of physical activity during one’s life impacts the risk of developing colon cancer. In a recently published study, researchers examined the differences in colon cancer incidence in relation to levels of physical activity at different stages of life. 

Researchers conducted a baseline survey in 1995 and 1996 of adult men and women to measure exposures to moderate-to-vigorous physical activity (MVPA) and several other lifestyle-related factors among nearly 300,000 adults (50-71 years). Study follow-ups ceased in 2011 or following any diagnosis of colon cancer or death. 

In the primary exposure assessment, participants were asked to report and quantify MVPA they had participated in at various stages of their life: at ages 15-18, 19-29, 30-35, and in the previous decade. MVPA levels were measured by time:

  • Rarely or none
  • Less than 1 hour a week
  • 1-3 hours a week
  • 4-7 hours a week
  • Greater than 7 hours per week 

Pattern Recognition and Impact on Colon Cancer Risk

Researchers identified specific patterns of MVPA:

  • Maintaining the same general level of physical activity throughout the life course (whether low, moderate, or high levels of MVPA) 
  • Raising levels of physical activity during the life course, either earlier or later in life (increasers) 
  • Reducing the amount of MVPA over time, either earlier or later in life (decreasers) 

Several key findings emerged from these patterns: 

  • Participants who maintained high MVPA levels throughout their life had a 15% lower risk of colon cancer than those who maintained low MVPA levels throughout their life
  • Participants who increased MVPA levels at a younger age had a 10% reduced risk of colon cancer, and participants who increased MVPA levels at an older age had an 8% reduced risk of colon cancer
  • Decreasing MVPA levels during the life course resulted in a 12% higher risk of colon cancer incidence when compared with individuals who maintained low MVPA levels throughout their life

These findings suggest that individuals who consistently engage in MVPA throughout their life and those who increase MVPA levels during their life have a lower risk of being diagnosed with colon cancer. They provide hope to individuals who may begin their fitness journey later in life. 

Emma Edwards is a Colorectal Cancer Prevention Intern with the Colon Cancer Foundation.

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