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How obesity increases risk of 13 different cancers in young adults

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*Condition associated with shorter life, more years with heart disease
*Freezing hunger nerve could help with weight loss, new study finds

A Case Western Reserve University School of Medicine in Cleveland, Ohio, United States (U.S.), researcher has compiled evidence from more than 100 publications to show how obesity increases risk of 13 different cancers in young adults. The meta-analysis describes how obesity has shifted certain cancers to younger age groups, and intensified cellular mechanisms promoting the diseases.

Cancer typically associated with older adults over 50 are now reported with increasing frequency in young adults. Of the 20 most common cancers in the United States, nine are now reported in young adults.

According to the review published in Obesity, in 2016, nearly one in 10 new breast cancer cases, and one in four new thyroid cancer cases were in young people aged 20-44. The data show that with obesity rising among younger demographics, so are cancer rates.The new review integrates animal studies, clinical trials, and public health data to help explain rising cancer rates among young adults. It describes how the childhood obesity “pandemic” promotes cancer. It also offers approaches to better track—and hopefully avert—this public health crisis.

Young people with body mass indexes (BMIs) over 30 are more likely to experience aggressive malignancies, says author Nathan A. Berger, MD, Hanna-Payne Professor of Experimental Medicine; director of the Center for Science, Health and Society; member of the Case Comprehensive Cancer Center; and professor of medicine, biochemistry, oncology and genetics at Case Western Reserve University School of Medicine. According to his review, childhood obesity may have lasting effects that could lead to cancer early and late in life.

Obesity can permanently alter a young person’s likelihood of developing cancer. Even after losing weight, cancer risk remains. Says Berger, “If you are obese, you are at a higher risk of cancer. If you lose weight, it improves the prognosis and may lower your risk, but it never goes away completely.” Obesity causes changes to a person’s Deoxy ribonucleic Acid (DNA)/genetic material that can add up over time. These changes include genetic flags and markers—epigenetic modifications—that increase cancer risk and may remain long after weight loss.

Data from clinical trials and animal obesity studies further link excess weight to cancer. Berger’s review shows obesity accelerates cancer progression in several ways. It over activates the immune system to produce harmful byproducts like peroxide and oxygen radicals that mutate DNA. Obesity also alters a person’s metabolism, causing growth factor and hormone imbalances that help cancer cells thrive. In the gut, obesity changes intestine microbiota such that tumor-promoting species dominate. Acid reflux in obese individuals damages their swallowing tubes and heightens risk of esophageal cancer. Berger’s research confirms obesity promotes cancer by multiple simultaneous pathways. “Even if one pathway is successfully blocked, obesity-induced cancer takes another path,” he says.

Also, another study found that when middle-aged people were obese, men were 67 per cent more likely to have a heart attack, stroke, heart failure or cardiovascular death and women had 85 per cent higher odds compared to normal-weight peers.Obese people have shorter lives and even those who are just overweight spend more years living with heart disease than individuals who are a healthy weight, a U.S. study suggests.

Researchers examined data on more than 190,000 adults from 10 different studies conducted in the U.S. over the past seven decades that looked at weight and other factors that can influence the risk of heart disease. None of the participants had cardiovascular disease when they joined these studies, but at least 70 percent of men and about 60 percent of women aged 40 and older were overweight or obese.For middle-aged men 40 to 59 years old, the odds of having a stroke, heart attack, heart failure or death from cardiovascular causes was 21 percent higher for overweight individuals than for those at a normal weight, the study found. Overweight middle-aged women had 32 percent higher odds of having a heart condition or dying from it.

When middle-aged people were obese, men were 67 percent more likely to have a heart attack, stroke, heart failure or cardiovascular death and women had 85 percent higher odds compared to normal-weight peers.Extremely obese middle-aged men had almost triple the risk of having a heart condition or dying from it, compared with normal-weight men, and extremely obese middle-aged women had more than twice the risk of normal-weight women.

Also, doctors may have found a way to freeze a nerve in the back that carries hunger signals to the brain and reduces appetite, according to a report from ABC News.
Doctors from Emory University School of Medicine studied people who were “moderately” to “severely” obese to see if there is a connection between the “hunger nerve” and one’s ability to lose weight — and keep it off.The “hunger nerve,” also called the posterior vagal trunk, signals your brain that you’re hungry when your stomach is empty.“Ninety-five percent of people who embark on a diet on their own will fail or gain their weight back at the six- or 12-month mark,” said lead researcher Dr. David Prologo in a news video release. “The reason for this is the body’s backlash to the calorie restriction,” the interventional radiologist added.

Doctors were able to shut down the signal of the “hunger nerve” in 10 patients by surgically inserting a needle into the patient’s back, freezing the nerve for two minutes, with the guidance of live images from a CT scan.In seven, 45 and 90-day follow-up visits, patients reported a decreased appetite at each clinic appointment, with an average weight loss of 3.6 percent along with a 13.9 percent decrease in BMI numbers.

Melissa, who was the first patient, said in a news release video, “I had struggled with weight since my six-year-old was born … and I’m constantly rebounding [with various weight-loss programmes].”She said that after the procedure she is “literally never hungry.”“I’m not eating because I’m bored,” she said. “It’s gradually coming off, so now I know it’s not going to come right back on like all the previous diets that I’ve tried.”

The study was presented at the Society for Interventional Radiology Conference this week in Los Angeles.Prologo and his team plan to do a larger trial to better understand if the procedure works in a lasting way.Berger provides quantitative and anecdotal data supporting an association between early obesity and specific cancers. He cites one study of over 1.1 million Israeli men tracked over time. Those who were overweight in adolescence (age 16-19) had a 1.5-fold increased risk of developing colon cancer by age 48.

Another study, says Berger, asked adults to draw their adolescent body shapes. “Patients who drew a round body shape had a higher incidence of multiple myeloma.” Such anecdotal evidence hints at long-term effects of childhood obesity, which Berger supports with other analyses. Adults with a history of obesity are twice as likely to develop multiple myeloma. Berger says obesity can also shorten cancer timelines, in part by shrinking the period between benign and malignant cancer progression. This is likely another reason aggressive cancer rates are rising among young adults. Multiple myeloma is now reported in young adults under 45, while historically the peak incidence age held steady at 69 for decades.

The review is a deep dive into 13 cancers previously identified by the International Agency for Research on Cancer as linked to excess body fat. But it is one of the first to specifically address how obesity promotes progression of these cancers in young adults. It includes Berger’s recommendations to disrupt the link between obesity and young adult cancers.

Berger suggests documenting health data, including BMI, throughout a patient’s life is critical. Many cancer patients present after significant weight loss, which could cause doctors to overlook obesity-related factors. Berger hopes that increased use of electronic medical records will help build databases that can detect weight loss patterns—even if they occurred decades prior or are confounded by other health issues. Berger said, “By documenting characteristics like diet and environment of an obese person, we might be able to get an indication of a possible prognosis.”

Detailed information about a person’s weight history could help, as could early cancer screening techniques tailored to young people. But, Berger said, “the most effective way to curtail development of this problem is to prevent the expansion of the obesity pandemic in both children and adults.” Without this step, 110 million children and adolescents with obesity worldwide remain at risk of developing obesity-associated cancers.Lead author of the first study, Dr. Sadiya Khan of the Northwestern University Feinberg School of Medicine in Chicago, said by email: “Our data clearly show that obesity is associated with a shorter, sicker life with more cardiovascular disease and more years lived with cardiovascular disease.”

“Obesity or excess fat in the body can increase risk for heart disease in and of itself as well as increasing risk for heart disease by causing elevated blood pressure, diabetes and abnormal cholesterol.” Some research in recent years has suggested that overweight people may live longer than their normal-weight counterparts, a phenomenon often described as the “obesity paradox.” Much of this research didn’t account for how early in life people develop ill health, however, and the current study offers fresh evidence linking excess weight to an increased risk of developing cardiovascular disease and of dying from it, researchers note in JAMA Cardiology.

The current study also links obesity to a shorter life.While overweight men had a similar lifespan to normal-weight men, obese men lived 1.9 fewer years, and extremely obese men died six years sooner.Middle-aged women who were a normal weight lived 1.4 years longer than overweight women, 3.4 years longer than obese women and six years longer than extremely obese women.The study wasn’t a controlled experiment designed to prove whether or how obesity impacts the chance of developing cardiovascular disease or dying from it.

Another limitation is that researchers only had data on weight when people joined the studies, but not on any weight fluctuations over time. The study also assessed obesity using body mass index (BMI), a measure of weight relative to height that doesn’t take into account how much lean muscle versus fat people have.A BMI between 18.5 and 24.9 is considered a healthy weight, 25 to 29.9 is overweight, 30 or above is obese and 40 or higher is what’s known as morbidly or extremely obese.

An adult who is 5’ 9” tall and weighs from 125 to 168 pounds would have a healthy weight and a BMI of 18.5 to 24.9, according to the U.S. Centers for Disease Control and Prevention. An obese adult at that height would weigh at least 203 pounds and have a BMI of 30 or more.Results from the current study suggest there are no health benefits to a higher BMI, said Dr. Haitham Ahmed, medical director of cardiac rehabilitation at the Cleveland Clinic in Ohio.“This study showed that risk was highest in obese patients, but even overweight patients had increased risk of cardiovascular disease,” Ahmed, who wasn’t involved in the study, said by email. “So we certainly encourage weight loss down to a normal BMI.”



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