Cancers among Black Americans are already a cause for concern, now younger adults have reason to take extra precautions. New research shows that cancer among younger adults is a growing global problem and is likely related to factors like poor diet, obesity and inactivity.
Since the 1990s, researchers say, rates of various cancers have been rising in many countries among people under 50. And while the reasons are not fully clear, it's likely that changes in lifestyle and environment — starting early in life — are playing a role.
The review found that in recent decades, rates of 14 cancers have been inching up annually among younger adults in a diverse range of countries — from the United States and Canada, to Sweden and England and to Ecuador, Uganda and South Korea.
The cancers, similarly, run the gamut and include those of the breast, colon, esophagus, kidneys, liver, stomach and pancreas.
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For certain cancers, increased screening may partly explain the rising incidence, according to senior researcher Dr. Shuji Ogino, of Brigham and Women's Hospital in Boston. Screening tests for diseases like breast and colon cancers can detect more cases, at an earlier point in time.
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The role of the microbiome
But for the most part, he says, the growing cancer incidence among younger adults is beyond what would be expected from heightened detection.
And many of the cancers that are increasing arise along the digestive tract — "anywhere from the mouth to the anus," Ogino shares. That, he adds, points to a potential role for the microbiome.
So what is the microbiome and why is it so important to our health?
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The microbiome refers to the vast array of bacteria that normally dwell in the body, largely the digestive tract. Research in recent years has been revealing how important the microbiome is to overall health, playing a role in immunity, fighting chronic inflammation and other vital functions.
For any one person, makeup of the microbiome depends partly on genes. But Ogino notes that environmental factors are critical, too — including diet, alcohol intake, smoking, exercise and antibiotic use.
What we put into out bodies really matters.
The spread of the "westernized" diet is a clear example, Ogino says. It's high in heavily processed foods, added sugar and red meat, but low in fruits, vegetables, fiber and "good" fats — qualities that have been linked to increased risks of certain cancers, like colon cancer.
The rise in colon cancers among younger adults has been gaining particular attention. According to the U.S. National Cancer Institute, the incidence of that disease among Americans younger than 50 has more than doubled since the 1990s — in sharp contrast to a decrease among people older than 65.
In fact, the trend spurred experts to lower the recommended starting age for colon cancer screening. It's now age 45 for people at average risk of the disease.
Dr. Benjamin Weinberg, an associate professor at MedStar Georgetown University Hospital in Washington, D.C., is studying the potential role of the gut microbiome in earlier-onset colon cancer. He also treats patients with the disease.
When a younger adult develops colon cancer, Weinberg says it suggests that something in the immune system response to early tumors has gone awry.
There is some evidence, he adds, that greater diversity in the gut microbiome may support that immune response.
On the other hand, certain bacteria might stymie it. A bug normally tied to gum disease — Fusobacterium nucleatum — is a case in point. Research suggests F. nuc may promote cancerous growths by suppressing the immune response in the colon. And Weinberg and his colleagues have found that colon tumors from younger adults have a high presence of the bacteria.
Obesity among children and younger adults has, of course, skyrocketed in recent years. And on the population level, Weinberg says, there is a relationship between obesity and colon cancer risk. But many younger people who are diagnosed with the disease are not obese, and the reasons behind the rising incidence would appear to go beyond a single factor.
Much more research is needed to understand what's driving the rise in various early-onset cancers, according to both doctors.
What can you do to prevent cancer?
Fortunately, there are some immediate changes you can make to prevent cancer.
For starters, take a close look at the foods you are putting into your body. How healthy are they?
You should be eating a healthy diet full of nutrient-rich whole foods (which may promote a diverse gut microbiome, among many other benefits).
Next, take a look at how active you are. Are you exercising on regularly?
Lastly, take a long at any other additional unhealthy habits you can cut out of your life. This includes smoking limiting alcohol use and taking antibiotics only when necessary.
Ogino says healthy lifestyle habits should be cultivated early in life. So if you have children, it will be important to practice these healthy lifestyle changes with them as well.
"I think the most important message is: Your kids' cancer risk in the future depends on what you do now," Ogino notes.
He adds, though, that in a world of easily accessed junk food and sedentary screen time, parents need help. It's up to society, Ogino says, to prioritize healthy eating, regular exercise, healthy sleep patterns and more.
