Why are more young people getting cancer ?

People in their 20s, 30s, and 40s are experiencing an increase in the incidence of breast, colorectal, and other malignancies. What is happening?

The incidence of colorectal cancer in individuals aged 25 to 49 has risen in 24 nations in the last ten years, including the US, UK, France, Australia, Canada, Norway, and Argentina.

The preliminary results of the inquiry were as striking as they were alarming, and they were presented by a multinational team at the September 2024 Union for International Cancer Control (UICC) meeting in Geneva.

To comprehend the pattern, the researchers—from the American Cancer Society (ACS) and the International Agency for Research on Cancer of the World Health Organization (WHO)—surveyed data from 50 nations. Only younger persons in 14 of these nations showed an increasing trend; rates for older adults remained steady.

The findings are the most recent in a string of research demonstrating a comparable increase in a variety of malignancies in young people. 

One type of cancer where the pattern is seen is breast cancer. According to a recent ACS research, incidence rates of breast cancer are increasing by 1% year overall and 1.4% annually for women under the age of 50, despite a 10% decrease in female breast cancer mortality over the previous ten years.

Epidemiological studies appear to indicate that this trend started in the 1990s. According to one study, between 1990 and 2019, the incidence of early-onset cancer grew by 79% worldwide, while the number of deaths from cancer among younger individuals climbed by 29%. An additional study published in The Lancet Public Health detailed how the US has seen a consistent increase in the incidence of 17 different malignancies among its generations, with Millennials and Generation Xers seeing the highest rates.

Early-onset malignancies have become such a serious problem that leading groups, including the UICC, are trying to educate general practitioners about the trend so that younger patients' warning signals are identified.

"A doctor listening to somebody above 60 who's talking about difficulty passing stool, feeling tired and bloated, is going to take those symptoms a lot more seriously than a young person in their 30s who's active and doesn't fit the typical profile of a person with cancer," says Sonali Johnson, the head of advocacy for the UICC. "They might put it down to irritable bowel syndrome or work stress, so there's plenty of cases where people's symptoms are dismissed instead of being referred for blood work or a colonoscopy."

According to cancer doctors, patients who arrive with illnesses such as pancreatic cancer, which typically affects people in their early 70s, might often be decades younger than anticipated.

As a gastrointestinal medical oncologist at Memorial Sloan Kettering Cancer Centre in New York, Eileen O'Reilly says, "It's not uncommon for me to see someone under the age of 40 with pancreatic cancer." The notion that it occurs virtually every week is unsettling. These are individuals in the prime of their lives, beginning families and living life to the fullest. There are significant ramifications for society.

Although younger malignancies have traditionally been assumed to be predominantly caused by heritable risk factors, such as mutations in the BRCA1 or BRCA2 genes in the case of breast cancer, an increasing number of individuals do not exhibit any clear genetic propensity. When examined in a lab, the tumors carried by patients in their 20s, 30s, or 40s appear to be more aggressive than those carried by a normal pancreatic cancer patient in their 70s, according to O'Reilly, who notes that in the majority of cases with youthful onset, there is no clear hereditary reason.

According to her, even if the patient is frequently in generally excellent condition, this frequently results in a very negative prognosis for them.

"They're younger, fitter and can often handle treatment intensity better, but some have this highly aggressive form of pancreatic cancer, which causes an accelerated decline in front of your eyes," she explains. "To them and us it's often beyond comprehension, because who could imagine that a healthy 40 year old would develop this kind of malignancy?"

In addition to identifying the trend, cancer doctors are experiencing a growing sense of urgency to investigate the underlying causes. The Lancet study's authors noted that if this tendency persisted, it would eventually raise the burden of disease in the future and perhaps reverse decades of advancements in public health in the fight against cancer.

So what is going on?

Some scientists have hypothesized that elements in highly processed diets may contribute to
colon inflammation and DNA damage.

The most apparent explanation, perhaps, focuses on the impact of obesity and metabolic syndrome, illnesses linked to an increased risk of cancer through systemic inflammation and disruption of important hormonal networks.

A recent study discovered that gaining extra weight between the ages of 18 and 40 is linked to an increased risk of up to 18 different cancers. Meanwhile, a report published in the Lancet revealed that 10 of the 17 cancers that are becoming more common among young people in the US are related to obesity and include myeloma, kidney, ovarian, liver, pancreatic, and gallbladder cancers.

Shuji Ogino, a Harvard University professor of pathology and epidemiology who has been studying the rise in early-onset malignancies, argues that "the overall evidence points to lifestyle change." "There are hundreds of genetic variations in each of us, and some of them carry a very little elevated risk of cancer, which increases in combination with certain environmental changes.

We are aware that developing insulin resistance, regularly having high blood sugar, and consuming a diet heavy in sugar and processed foods increase the risk of both diabetes and cancer." 

However, obesity on its alone does not tell the whole issue. Many of the younger patients with pancreatic cancer that O'Reilly encounters are outwardly healthy and fit, with no obvious reason for them to have become ill. "It certainly always strikes me that the traditional things we think about mostly don't apply to these people," she continues. "They appear often healthy, vibrant and extremely physically fit."

According to Ogino, this could be due to the rise of some new carcinogens that have received less attention in the past. Although epidemiologists have long concentrated on the connection between smoking and cancer, the WHO reports that, globally, just one in five persons currently use tobacco products, down from one in three in 2000. This indicates a significant reduction in smoking prevalence over the past several decades.

Rather, Ogino believes that a largely ignored link is the noticeable shift in global sleep patterns that has taken place over the past 50–100 years.

According to one research, children and adolescents slept for an average of 60 minutes less per night between 1905 and 2008, despite shift work being more and more common in North and South America, Australia, China, Japan, and Europe in recent decades. A research conducted in 2021 that used information from the English Longitudinal research of Ageing, a database that includes data from over 10,000 individuals over 50, discovered a link between higher cancer risk and poorer sleep quality.

Certain scientists have even suggested that our almost constant exposure to artificial light—whether from streetlights, cell phones, or tablets—represents a novel carcinogen since it causes interference with the body's circadian rhythm, which has been connected to cancers of the breast, colon, ovary, and prostate. 

Research has also indicated that working shifts and remaining exposed to light during the night may promote the formation of cancer by decreasing melatonin levels.

"We are exposed a lot to artificial light at night, even from when we are babies," Ogino claims. And a sizable portion of people in Japan, for example, remain up till midnight every night. The prevalence of shift employment has increased due to establishments like 24-hour convenience shops."

According to Ogino, a number of these early-onset cancer cases are most likely the result of a combination of factors rather than a single risk factor, together to drive the illness. 

According to some experts, our exposure to artificial light from devices like
smartphones may be a new .

Many cancer specialists think that the effects of numerous harmful alterations inside the stomach are a major factor behind many illnesses, especially when combined with changes in lifestyle.

A call to action for colorectal cancer specialists worldwide was made in June 2023 by Frank Frizelle, a colorectal surgeon at Christchurch Hospital in New Zealand, who advocated for more investigation of the potential link between eating a lot of microplastics and getting colon cancer too soon.

He made a bold claim in his work "Could microplastics be a driver for early-onset colorectal cancer?": The exponential growth of microplastics found in the environment has coincided with the growing prevalence of colorectal cancer as a serious health concern in people under 50. He suggests that the colonic mucus layer, which shields the intestinal lining from numerous viruses and poisons from our diet, may be compromised by the presence of these microscopic plastic particles.

"Micro and nano plastics may allow the mucus layer to be permeated in some way, like putting a series of pin holes in a condom," according to him. "If we can prove this to be true, it might be size related, like carbon particles and lung disease."

Though this is still mostly conjecture, Frizelle is by no means the first researcher to have connected harmful alterations in the gut to mechanisms that may cause cancer. Similar to microplastics, there is currently a dearth of data to support the claims made by some researchers that specific ingredients in ultra-processed meals, such as food colorants and emulsifiers, may contribute to inflammation and DNA damage in the colon. 

Significant alterations in the gastrointestinal tract are linked to colorectal cancer as well as a variety of solid tumors, such as breast and blood cancers, since the colon is related to the stomach, the gastrointestinal tract as a whole, and the immune system.

Researchers are investigating the possibility that antibiotic usage may play a role. In relation to microplastic exposure, the global usage of antibiotics has increased in the previous several decades. Specifically, from 9.8 per 1,000 persons in 2000 to 14.3 in 2018, children under the age of five ingested higher dosages of antibiotics. O'Reilly considers this to be a major reason for worry, as the worldwide per-capita use of antibiotics increased between 2000 and 2015 across all age categories.

Increased exposure to antibiotics has been related to lung cancer, lymphomas, pancreatic cancer, renal cell carcinoma, and multiple myeloma in the past. This is because antibiotics have the power to eradicate vast tracts of bacterial species, radically altering the gut microbiome in potentially hazardous ways.

"The bacteria that live in the gut have been selected by some sort of Darwinian process and they're part of the immune surveillance which allows our immune system to recognise abnormal cells, foreign particles, and prevent the genesis of malignancies in the first place," O'Reilly explains. "It's still not known, but the idea is that greater antibiotic exposure could mean that immune surveillance is not working as effectively as it should."

Eliminating so-called commensal bacteria, which are species that are naturally present in the gut, might lead to a gap that can later be filled by more pathogenic microorganisms. This is one of the possible effects of overusing antibiotics. Over the past ten years, a number of research on certain opportunistic infections that appear to be able to invade the gut and cause cellular alterations that raise the risk of cancer progression have been published by Ogino and his international partners. 

Specifically, Ogino et al. have discovered that Fusobacterium nucleatum appears to be the causative agent of both more aggressive tumor development and precancerous intestinal growths. According to other research, some E. coli species may be able to both promote the growth of cancer and inhibit the immune system at the same time.

According to Ogino, the variables influencing early-onset cancer are complex and vary from infancy to maturity. They may work in concert to progressively raise the chance of developing the illness in early adulthood, just like sleep and obesity do. While most of us carry some type of E. coli, he notes that studies has revealed that diet has a significant influence as well. These bacteria tend to proliferate when we consume a so-called "Western diet" that is heavy in ultra-processed foods.

We still have a ways to go before we can pinpoint the precise reason why certain populations have ended up with early-onset malignancies. 

"There's an enormous need for research to try and understand what's going on and what's inciting these diseases at a much earlier stage," she continues. The fact that pancreatic cancer and other solid organ tumors are becoming more common in young people worries me greatly. It seems like a serious public health emergency to me.

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