Millennials – people born between 1981 and 1995 – are the first generation at greater risk of developing tumours than their parents, writes Lydia Begoña Horndler Gil in The Conversation.
Between 1990 and 2019, cases of early-onset cancer among people under 50 increased by a staggering 79% worldwide, and mortality by 28%, she writes.
The truth is that around 80% of cancers are “sporadic”, meaning they are not caused by hereditary mutations but by external factors that damage DNA over time. This includes what we eat and breathe, as well as our level of physical activity, rest, stress and exposure to harmful substances.
In other words, the things that make the biggest difference are lifestyle factors surrounding us every day, and not the genetics we inherit. And we know that our parents’ and grandparents’ lifestyles differed greatly from our own.
Diet’s effect on the body
One of the main factors behind this “new epidemic” is diet. Childhood obesity began to skyrocket in the 1980s. In 2022, more than 390m children and adolescents aged five to 19 were overweight – 160m of these were obese.
This condition is not just a question of aesthetics: it is associated with insulin resistance, low-grade chronic inflammation, and hormonal changes that increase the risk of developing colorectal, breast, or endometrial cancer.
Most importantly, the effects of childhood obesity do not disappear with age. According to the Colon Cancer Foundation, a meta-analysis involving more than 4.7m people showed that those with a high body mass index (BMI) in early life are at greater risk of colorectal cancer in adulthood: 39% higher in men and 19% higher in women compared to those who had a healthy BMI in childhood.
Changes in diet have also altered our gut microbiota. It has been shown that diets rich in ultra-processed foods reduce bacterial diversity, and increase the proportion of strains that produce pro-inflammatory metabolites.
This contributes to gastrointestinal diseases like irritable bowel syndrome or SIBO, which often seem to be endemic among millennials.
Alcohol’s invisible effects
The second major culprit is alcohol, as millennial gatherings often revolve around a table laden with food and drink. For years it was thought that a glass of wine was could “protect” you in some way, but today we know that there is no safe level of alcohol consumption: the International Agency for Research on Cancer classifies it as a Group 1 carcinogen, on the same level as tobacco.
This is because the body converts ethanol into acetaldehyde, a compound that damages DNA.
Furthermore, consumption patterns differ between generations. While baby boomers (born between 1946 and 1964) drink more on a daily basis, millennials tend to drink less frequently but engage in more binge drinking, which carries significant risks.
This is confirmed by the Spanish Ministry of Health’s 2024 EDADES survey, which explores the different levels of risk associated with different behaviours across generations.
And, as if that weren’t enough, a recent study by Environmental Science & Technology found that many beers contain perfluoroalkyl substances (PFAS). These “forever chemicals” are linked to higher rates of testicular and kidney cancer.
Not enough sleep
We sleep less and worse than previous generations. Recent surveys show that millennials and generation Z get an average of 30-45 minutes less sleep per night than baby boomers, largely due to night-time exposure to screens and social media. This artificial light disrupts the release of melatonin, an antioxidant hormone that regulates the cell cycle.
Chronic lack of sleep not only impairs DNA repair, but also reduces melatonin’s protective effects against cancer. Reduced levels of this hormone have been linked to a reduced ability to counteract oxidative DNA damage and increased cell proliferation.
Furthermore, disrupted circadian rhythms interfere with the expression of genes that are key to repairing DNA. This means mutations accumulate over time, increasing the risk of tumour-forming processes.
The weight of stress
Millennials are probably the generation with the highest cortisol levels. When this “stress hormone” remains elevated for a long time, it not only promotes insulin resistance and hypertension, but also weakens the immune system.
Research reveals that chronic stress increases inflammation, hinders the body’s defences from eliminating abnormal cells, and can even “awaken” dormant tumour cells. In fact, studies in the general population have found that people with higher stress levels are up to twice as likely to die from cancer as those who manage stress better.
The risks of self-medicating
Last, younger generations also resort to self-medication more than previous ones. This poses new short and long-term risks.
Frequent use of paracetamol is linked to increased liver damage and a possible increase in liver cancer. Oral contraceptives, used for very long periods, slightly increase the risk of breast and cervical cancer, although they do protect against ovarian and endometrial cancer.
In addition, prolonged use of antacids and antibiotics has been linked to an increased risk of digestive cancer through indirect mechanisms such as carcinogenic compounds or intestinal dysbiosis (an imbalance in the gut microbiota).
What does the future hold for millennials?
The projections are worrying. It is expected that cancer cases could rise from around 20m in 2022 to nearly 35m in 2050 – an overall increase of almost 77%. The trend is particularly marked in digestive and gynaecological tumours, which are becoming more and more common in young adults.
We are the generation of immediacy, anxiety and quick-fix pills, but all is not lost, as we can take control of many of the factors that make us ill, starting today.
Adopting healthier habits can reduce risks, and improve our quality of life in a future that is not as distant as we might like to believe.
Lydia Begoña Horndler Gil – Profesor en inmunología y biología del cáncer, Universidad San Jorge, Spain.
The Conversation article – Why are so many millennials getting cancer? (Creative Commons Licence)
See more from MedicalBrief archives:
Increase in several cancers among adults of all ages – global study
Steep climb in under-50 cancer cases, global study finds
Millennials and Gen Xers have higher risk of 17 cancers – US study