Certain cancers are showing up more often in younger adults. Researchers believe obesity is to blame.
A comprehensive study published this week found that 6 out of 12 types of cancer thought to result from being significantly overweight are becoming notably more common among those under the age of 50.
What’s more, the younger the patient, the more common certain cancers were.
The findings, published in The Lancet Public Health, noted a significant increase in the incidence of multiple myeloma — rare cancer that attacks the bone marrow — along with colorectal, uterine, gallbladder, kidney, and pancreatic cancer.
Obesity has also been linked to cancer of the stomach, liver, breasts, ovaries, esophagus, and thyroid.
The study’s authors said their work is the first since the mid-1990s to review trends in the incidence of these 12 obesity-related cancers. They compared them with 18 other cancers among younger adults.
The team reviewed 20 years of data on those cancers, studying information from state registries on patients ranging in age from 25 to 84.
They found more than 14 million cases diagnosed from 1995 through 2014 for the 30 types of cancer.
“What makes this study relevant is that it’s very large,” said Dr. Anton Bilchik, a professor of surgery and chief of medicine at the John Wayne Cancer Institute in California.
That obesity-related cancers are showing up in relatively young people has been the subject of multiple studies in recent years.
What’s striking about this latest research, Bilchik told Healthline, is both its scope and the discovery that the incidence of some of these diseases is rising among successively younger groups.
By contrast, rates either dropped or held steady in all but 2 of the 18 cancers not related to obesity.
Bilchik is seeing the trend among his own patients.
In the past week, Bilchik operated on four individuals under 55 with diagnoses of advanced-stage cancers that usually affect people in their 60s and 70s.
Two of them were obese and the other two had been overweight as children, which Bilchik thinks also predisposed them to cancer.
One example of the inverse relationship between risk and age is pancreatic cancer.
The study’s authors found the incidence of that disease changed .77 percent per year on average in the 45- to 49-year age group.
By contrast, the annual incidence rose by 2.47 percent on average among 30- to 34-year-olds. In the 25- to 29-year-old cohort, the average yearly change was 4.34 percent.
Although adults ages 50 and older also experienced steady increases in the incidence of most of those obesity-related cancers — colorectal and uterine were the exceptions — the magnitude of those changes was smaller than among younger age groups, except for thyroid cancer.
What’s the connection?
The connection between obesity and certain cancers remains unclear, as does the reason for the uptick of those illnesses in ever-younger populations.
However, medical experts have some theories.
Experiments on mice have shown that obesity accelerates the uncontrolled growth of cells, which could result in human malignancies being discovered earlier in life, the recent study reported.
Obesity has been an increasingly worrisome problem for decades now.
An estimated 40 percent of adults and 18 percent of young people in the United States are obese, despite national guidelines that recommend doctors screen children and young adults for obesity.
The recent study noted that fewer than half of primary care physicians routinely calculate their patients’ body mass index and only one-third of people with obesity report that their doctor determined they were substantially overweight or referred them to weight loss counseling.
But there are other aspects of the problem as well.
Genes, metabolism, and exposure to environmental factors such as processed foods might also play a role in obesity, said Dr. George Chang, professor of surgery and chief of colorectal surgery at the University of Texas MD Anderson Cancer Center in Houston.
“It’s certainly a very complex issue and that’s why it’s such a difficult public health problem,” Chang told Healthline.
Finding a solution will require the efforts of all stakeholders, Chang said.
“I think everybody’s responsible,” he said.
Individuals need to understand the consequences of poor lifestyle choices and healthcare providers should be impressing the importance of proper diet and exercise with their patients even though it can be a sensitive topic for those who are overweight, Chang said.
Policy makers also have a role to play. One way could be limiting students’ access to food and sugary drinks that contribute to childhood obesity, Chang said.
The study noted that although some communities are taxing sodas and creating pedestrian-friendly areas to boost physical activity, they remain the exception.
Obesity itself isn’t necessarily the only culprit in a younger person’s cancer diagnosis, however.
Other health complications that excess weight can cause — such as diabetes and gallstones — are also associated with cancer, according to the report.
So is a diet that’s top-heavy with red or processed meat but short on fruits and vegetables.
Whatever the cause, the study concluded that the growing problem of obesity-related cancers in younger generations ultimately could stop or even reverse the progress that’s been made in reducing cancer deaths.
The bottom lineA new study says cancers related to obesity are on the rise among younger adults.
In particular, there has been a significant increase in multiple myeloma, colorectal, uterine, gallbladder, kidney, and pancreatic cancers.
In addition, the younger the age group the higher the increase was.
Researchers said doctors need to emphasize healthy eating choices as well as exercise routines to younger people.