Early-Onset Colorectal Cancer on the Rise: Can Diet Help?

Early-onset colorectal cancer rates are trending upward, including adults in their 20s, 30s and 40s. This cancer is still far more common after age 50. But the rate of increase in younger adults has prompted intensified research. Who is most at risk? Can diet and other lifestyle choices reduce risk?

 

Colon cancer first rocked my world as a little girl. My first experience with death of a close
family member was when my grandpa died of colon cancer. He was 78.

Since then, survival rates have improved, and overall incidence of this cancer has declined.

 

But an unfortunate trend has been flying under the radar for most of us.

Rates of colorectal cancer have been increasing in recent decades among people many might consider “too young” to develop this disease.

You can learn more about these trends in early-onset colorectal cancer — and what we might be able to do about it — from this research review. Listen to my interview with researcher Yin Cao, ScD, MPH, who has been studying early-onset colorectal cancer extensively.

 

 

Early-Onset Colorectal Cancer Trends: Why the Concern?

Colorectal cancer (CRC) is the third most common cancer in both men and women.

Yes, most cases of colorectal cancer still occur in adults ages 50 and older.

• Like most types of cancer, the risk of CRC increases with age. With every 5-year increase in age, incidence of colorectal cancer approximately doubles until age 50. After that, each 5-year increase in age group signals a 30% increase in incidence rates. [These incidence rates are expressed as number of cases per 100,000 people.]
• For more than a decade, age-adjusted rates of new cases and mortality rates have been falling about 2% per year. Increased use of coloscopies and other forms of screening have allowed physicians to detect polyps before they become cancerous, and cancers while they are at earlier stages. Decreased smoking (which is a risk factor for CRC) may also have contributed to the falling rates.     

 

Are young adults too young to think about colorectal cancer? Think again.   

• Current estimates project 12% of colorectal cases to be diagnosed in people younger than age 50. This is early-onset colorectal cancer (EO-CRC), sometimes called young onset CRC.
• Rates of colorectal cancer among people in their 20s, 30s, and 40s have been climbing since the mid-1980’s. As Dr. Cao explains in our interview, “We have observed a birth cohort effect for early onset-colorectal cancer. Elevated risk is observed among individuals born after 1950. And this birth cohort [a group of people born in the same time period] has carried the elevated risk as they age.”

 

 

What’s Behind Risk of Young Onset Colorectal Cancer?

• Family history and hereditary mutations may be present in about 30% of people with EO-CRC.
  • Genetic predisposition occurs in less than 5% of CRC overall. But about 16% to 22% of people with EO-CRC have mutations in genes such as tumor suppressor genes. Among these, Lynch syndrome is most common in EO-CRC.
  • Family history of CRC or advanced colorectal adenomas, especially in a first-degree relative, even without a recognized genetic syndrome, also significantly increases risk of overall CRC and EO-CRC.
• Certain medical conditions increase of CRC, including a history of high-risk adenomas or ovarian cancer. Chronic inflammatory bowel disease (ulcerative colitis or Crohn’s disease) and type 2 diabetes also signal increased risk.
• But modifiable risk factors account for more than half of US CRC. In our interview, Dr. Cao explains, “Based on current research, this increasing prevalence of early-onset colorectal cancer seems to be as strongly related to lifestyle as in overall colorectal cancer.”

 

CRC usually develops from a noncancerous polyp in the colon or rectum.

• Polyps are common after age 50. Most never develop into cancer. But over 10 to 20 years, sometimes a polyp becomes cancerous.
• EO-CRC most often occurs in the distal colon and rectum, and usually develops from an adenoma type of polyp.
• Some research suggests that these findings mean that EO-CRC may be especially associated with diet. And understanding diet’s role in development of adenomas that are most likely to develop into cancer could be especially valuable for reducing risk of early-onset CRC.

 

How Diet May Yield Triple Power Starting Sooner than You Think

Poor diet quality has been linked to greater risk of CRC overall. Research results point to several ways that eating habits could play a role in the many stages through which colorectal cancer develops.

• Chronic inflammation leads to production of free radicals that damage DNA. It also enhances cell signaling that seems to dial up expression of oncogenes (genes that increase cancer cell growth) and dial down tumor suppressor genes.
• Elevated levels of insulin lead to enhanced signals for cell growth and inhibited apoptosis (self-destruction of abnormal cells). Diet can directly affect insulin levels. And if it leads to unhealthy weight gain, changes in insulin levels and effectiveness can be magnified.
• Diet shapes the gut microbiota and the types of bacteria that thrive in each individual. These bacteria, in turn, produce substances that affect gene expression, gut wall barrier function, intestinal immune factors, and intestinal cell reproduction and growth. – The intestinal microbiota of people with colorectal cancer tends to have a greater proportion of bacteria that promote inflammation in the gut or produce carcinogenic metabolites, and a smaller proportion of bacteria that produce butyrate (a short-chain fatty acid that protects colorectal cells).

Diet’s influence on EO-CRC risk may stem not only from diet as a young adult, but also from diet earlier in life. This fits with the understanding that colorectal cancer develops over many years. And some researchers suggest that the growth factor and metabolic changes during youth and adolescence may indicate a time of greater sensitivity to diet’s effects on insulin, DNA damage and repair, and changes in the gut microbiome.

Cultural changes in overall diet and lifestyle that began around the 1950s would have affected people in early life during the 1950s to 1980s. That would coincide with the birth cohort rise in EO-CRC that began in the 1980s to 2010s. National dietary surveys (NHANES) from 1999 to 2016 shows modest improvement in overall diet quality of US youth. But depending on age and demographic group, 40% to 65% of youth in the 2016 survey had poor-quality diets.

 

Here’s my interview with Yin Cao, ScD, MPH.    

Listen as she describes what research has found about early-onset CRC and the potential for eating habits to reduce risk.

 

Foundational Power 4: Where Evidence on Diet is Strongest

Diet is an important influence on risk of overall colorectal cancer. We need more research to understand whether the same key elements play a similar role in young onset colorectal cancer. But for now, these do provide a helpful starting point for a checklist.

Dietary Fiber

• Analysis for the most recent American Institute for Cancer Research (AICR) report categorizes evidence as strong that high-fiber diets reduce risk of colorectal cancer. Each step above 10 grams of fiber per day is associated with a progressively lower risk. But average US intake is only 16 grams/day.
  • Less than 5% of Americans reach the AICR recommendation of 30 grams per day for adults or the age-based dietary standard for youth.
  • Rather than relying on a single super food or supplement to meet fiber targets, collect it throughout the day from a variety of foods to get a wide array of fiber types.
• Why? Dietary fiber is the source of butyrate and other short-chain fatty acids produced by gut bacteria. Butyrate, especially, reduces markers of inflammation in laboratory studies and human clinical trials, and shows effects on gene expression and immune function that could reduce cancer development. Some types of fiber may protect colorectal cells through effects on insulin levels. Other types provide protection by adding bulk and speeding passage of waste for excretion.

Red Meat and Processed Meat

• Red meat (such as beef, lamb, and pork) in large amounts is strongly linked with increased overall colorectal cancer risk. One analysis of pooled data suggests this may be true for young onset colorectal cancer, too. Average intake of unprocessed red meat (like ground meat and chops, roasts, and steaks) has decreased slightly in the US over the last 20 years, and average intake is within AICR’s recommended limit of no more than 12 to 18 ounces per week. However, average figures mask some people’s consumption of considerably more.
• Still more concerning is intake of processed meat, which is linked with an even greater increase in colorectal cancer risk. This refers to meat that’s cured, smoked, salted, fermented or has added preservatives. Common choices include sausage, hot dogs, luncheon meat, and bacon. Despite 20 years of messages to limit processed meat as much as possible, US adult intake has remained unchanged at an average of nearly 7 ounces every week.
• Why? Risk likely involves effects on the gut microbiota, promoting growth of types of bacteria that produce the pro-inflammatory compound hydrogen sulfide. Red meat’s higher content of heme iron poses another concern. It can increase free radicals that damage DNA and promote the formation of nitroso compounds (NOCs). High-fat meats prompt the body to produce more bile acids for fat absorption. But metabolites of these bile acids (secondary bile acids) reach the colon, where they are potent in causing DNA damage. Processed meats can increase exposure to compounds such as the polycyclic aromatic hydrocarbons (PAHs) in smoked meats and nitroso-compounds formed when nitrites combine with amines of meat protein

Sugar-Sweetened Beverages

• Recommendations to limit sugar-sweetened drinks (including soft drinks, energy drinks, sports drinks) have been based on research of how frequent consumption promotes weight gain and excess body weight, which increase risk of several major cancers. However, analysis in a prospective cohort study (Nurses’ Health Study II) shows risk of EO-CRC in women who consumed 16 ounces or more of sugar-sweetened beverages (SSB) daily more than doubled compared to women consuming less than 8 ounces/week. And that was after adjusting for body mass index (BMI) and other risk factors.
• Following up on theories that diet in youth may be particularly important for young onset colorectal cancer, women in this study who drank 16 ounces or more daily of SSB in adolescence showed more than three times greater risk of EO-CRC. Another study in the same population found that for each 12-ounce daily SSB during adolescence, risk of colorectal adenomas increased more than 30%. And risk of the rectal adenomas that are especially associated with colorectal cancer before age 50 similarly increased.
• Why? The large load of sugar from SSBs causes a rapid rise in blood sugar and insulin secretion. Over time, these elevated levels of insulin can lead to insulin resistance, inflammation, obesity and type 2 diabetes. And all are linked to increased risk of colorectal cancer. Researchers are paying special attention to fructose, part of the sweetener in SSBs. Fructose is normally absorbed in the small intestine. But if large amounts exceed capacity for absorption, it can pass on to the large intestine. There, laboratory studies suggest it may change gut microbiota populations and damage the gut wall. Much more research is needed.

Dairy Products and Calcium

• Moderate consumption of dairy products (two or three standard servings) and calcium (700 to 1000 mg per day) show strong links in reducing risk of adenomas and CRC overall. Yet there’s no benefit in overdoing – calcium intake beyond 1000 mg per day doesn’t show any further reduction in CRC risk.
• Why? Calcium may offer protection by decreasing cell proliferation and by binding unconjugated bile acids so they can’t damage colorectal cells. Some research suggests that fermented dairy products (such as yogurt) that supply lactic-acid producing bacteria might also add support for a health-protective gut microbiome.

Overall Dietary Pattern – It’s Not One Size Fits All

Although studies show clear potential for each of these foods and nutrients to influence risk of colorectal cancer – and early-onset colorectal cancer in particular – it’s the overall pattern of your diet that’s what research identifies as the place to focus.

A Western diet was linked with increased risk of early-onset adenomas in the Nurses’ Health Study II (NHS-II) prospective cohort study. And women with highest scores were 67% more likely to develop high-risk types of early-onset adenomas (most likely to develop into colorectal cancer).

Limited evidence suggests this kind of diet may particularly increase risk of distal colon and rectal forms of colorectal cancer (the types most common in EO-CRC) and the molecular subtypes of CRC typical of young onset cases.

Scores indicating a Western diet are based on higher consumption of processed meat, red meat, butter, high-fat dairy products, eggs and refined grains.

A Prudent diet, on the other hand, may reduce risk of colorectal cancer. In the same NHS-II prospective cohort study, women with highest scores for a prudent diet were 30% less likely to develop high-risk types of early-onset adenomas.

Scores indicating a Prudent diet are based on higher consumption of vegetables, fruits, legumes (such as dried beans), whole grains, and fish. Whole grains have long been linked with lower risk of colorectal cancer in general. They provide not only fiber, but also phytochemicals such as phytic acid, phenolic acids and lignans that may protect colorectal cells and reduce inflammation. Although evidence is much more limited, AICR analysis suggests that fish consumption may be linked with lower risk of colorectal cancer.

More of the Best AND Less of the Rest?

What about combining lower consumption of foods that characterize a Western diet with high consumption of the protective foods in the Prudent diet?

Another analysis of data from women in the NHS-II compared women with high Western diet and low Prudent diet scores to women with low Western diet and high Prudent diet scores. Indeed, women in the latter group were 42% less likely to develop early-onset high-risk types of colorectal adenomas. And that was after adjusting for family history and things that often go along with a less healthy diet, such as calorie intake, overweight or obesity, and type 2 diabetes.

As Dr. Cao explained in our interview, this kind of overall healthy plant-based diet pattern can be created in a variety of ways that fit individual, family, and cultural preferences. Higher compared to lower scores for fit with a Mediterranean-style diet, with the DASH diet originally developed to control high blood pressure, and with Dietary Guidelines for Americans (using the AHEI-2010 index) were each linked with lower risk of early-onset colorectal adenoma.

And zeroing in on adenoma types most likely to develop into colorectal cancer, these healthy dietary patterns showed an even stronger protective potential – linked with 29% to 45% lower risk – even after adjusting for other known risk factors.

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5 Steps to Counter the Threat of Early-Onset Colorectal Cancer

Recommendations about how to reduce risk of cancer through lifestyle choices remain consistent. Amidst rising rates of colorectal cancer in early adults and middle age — and evidence that lifestyle-related risk likely begins at least in adolescence — the importance of reaching young adults with these evidence-based recommendations is now clear.

Create plant-focused eating habits that work for you. Dietary patterns linked with lower risk of early-onset colorectal cancer are high in vegetables, fruits, whole grains, legumes and nuts; with more unsaturated fats and less saturated fat; and limited red and processed meats and SSBs.

Dr. Cao emphasizes, “The consistency of these findings reinforces our message that maintaining a healthy diet is important in lowering risk of high-risk adenoma and colorectal cancer in younger adults.”

Limit alcohol and don’t smoke. Consumption of even the alcohol equivalent to two or more standard alcoholic drinks (30 grams of ethanol or more) per day raises overall CRC risk. That holds regardless of whether alcohol is consumed as wine, beer, or distilled spirits. And long-term tobacco use poses cancer risk well beyond the lungs, including colorectal cancer.

Maintain an individually healthy weight. Obesity and metabolic syndrome are linked with risk of colorectal cancer overall and early-onset colorectal cancer. Unhealthy increases in body fat stand at the crossroads of chronic inflammation, elevated levels of insulin, and abnormalities in the gut microbiome. And each of these changes seems involved in colorectal cancer. However, colorectal cancer occurs across a wide range of weights. A healthy weight does not mean someone can safely ignore other recommendations aimed at reducing risk.

Make physical activity a regular part of day-to-day life and limit sitting time. Even beyond its role in making it easier to avoid unwanted weight gain, more movement directly produces health-protective metabolic and hormonal benefits.

Pay attention to screening and symptoms. Major US CRC screening recommendations now advise average-risk adults to begin regular screening at age 45 instead of 50.

• This allows earlier CRC detection and treatment, and more opportunity to remove precancerous polyps before cancer develops.
• However, starting at age 45 won’t catch colorectal adenomas and early-stage cancers among some younger adults. Greater awareness of symptoms and less delay before seeking medical attention are needed.