Cancer cases in young adults are increasing. “Our diet, lifestyle and environmental factors have changed”

While the number of cancer deaths continues to fall, younger people, including those who appear healthy and fit, are increasingly suffering from cancers that used to be reserved for older age groups, the DailyMail reports.

The number of cancer cases among young people is increasing, archive photo

The Princess of Wales' diagnosis of cancer at just 42 is not a singular case, but reflects a worrying wider trend: because although early-onset cancers (in adults aged 18 to 49) account for only a fraction of the total number of cases, their incidence and death rates are increasing significantly worldwide.

In addition, survivors have a higher risk of long-term health problems such as infertility, heart disease and secondary cancers, according to the US National Institutes of Health.

Pollution and the genetic factor

“Studies show that rates of early-onset cancers, particularly breast, colorectal, pancreatic, thyroid and reproductive cancers, have risen steadily in recent years,” says Dr. Veda Giri, a leading expert in this field.

Professor Karol Sikora, a leading consultant oncologist and founding dean of the University of Buckingham School of Medicine, told Good Health: “Although lifestyle factors play an important role, they cannot explain everything, because a lot of healthy young people get cancer without obvious risk factors.”.

A 2023 study published in BMJ Oncology suggested a link between pollution and an increase in early-onset trachea, bronchus and lung (TBL) cancers. “Air pollution may emerge as an important risk factor for early-onset TBL cancer”, says this one.

Another factor taken into consideration was genetics. But cancers caused by inherited faulty genes are much less common than those caused by other factors, so researchers believe that the rise in the rate of the disease in young people is most likely linked to as-yet-unidentified environmental or lifestyle factors .

Modification of the intestinal microbiome

One possibility is recent changes in the gut microbiome, the community of fungi, bacteria and viruses that live in our gut and play an important role in inflammation and the immune system.

A recent study, published in January in the British Journal of Cancer, identified certain types of harmful gut bacteria in colorectal tumors taken from 1,687 patients. The researchers found that early-onset colorectal tumors (from patients under 45) had a different microbial profile than late-onset ones.

“One potential cause of this rising incidence is related to changes in our gut microbiome. In recent decades, our diet, lifestyle and environmental factors have changed, which can alter the type of bacteria as well as the balance between good and bad bacteria that live in our gut.” explained lead researcher Daniel Buchanan, associate professor who leads the Colorectal Oncogenomics Laboratory at the University of Melbourne.

Frequent use of antibiotics

Studies have also linked the increase in cases to increased antibiotic use.

The researchers concluded that “antibiotic-induced microbiome changes may be permanent” and affects the immune system's ability to attack cells “defective”, which turns into cancer. These changes can also allow bacteria “bad”
to develop quickly, “leading to inflammation and tumor formation”.

Dr. Daniel Buchanan and his team have identified three types of bacteria in the gut that produce chemicals that can damage DNA and lead to cancer. One strain in particular — a variant of E. coli that causes stomach infections — was more likely to occur in patients with early-onset colorectal cancer.

“This is the first time a non-genetic biomarker for the cause of colorectal cancer has been identified – now we can link the cause of cancer to this bacteria,” says Dr. Buchanan.

The researchers suggested that early exposure to this variant of E. coli, when our gut microbiome is still developing, could make a person more prone to the early onset of tumors.

Advanced age of the mother at birth

Social changes could also be driving this growth. More women are having children later in life, which appears to affect their children's risk of developing childhood cancers (although it is unclear whether this risk persists into adulthood).

Compared to children born to mothers between the ages of 20 and 24, those born to mothers in older age groups had a 13-36% higher risk of pediatric cancer, the American Journal of Epidemiology reported in 2017 The same study found that the father's age may also increase the risk.

Other researchers have suggested that the “environment” in the wombs of older mothers can affect the genes that are turned on or off in their offspring, making them more likely to develop cancers later in life.

The same time cancer can behave differently depending on age

If younger patients are experiencing problems specific to their age, they may also require an age-specific approach, as the same type of cancer can behave differently depending on age.

“Studies have shown that when some tumors appear earlier in life, they actually have different molecular properties. Cells in these early-onset tumors may mutate faster and be more aggressive, although no one knows exactly why.” say the specialists.

There is also good news. Early-onset cancers respond equally well to chemotherapy, according to Dr. Andrew Beggs, and “young and fit people cope better with chemotherapy and can receive higher doses without suffering permanent damage. If higher doses of chemotherapy can be tolerated, the tumor may respond better,” he says.