The Global Surge in Early-Onset Cancer
The number of people under 50 diagnosed with cancer has risen by nearly 80 per cent in three decades, with global cases increasing from 1.82 million in 1990 to 3.26 million in 2019, according to research published in BMJ Oncology. Deaths from the disease among those in their 40s, 30s or younger rose by 27.7 per cent over the same period. Projections suggest a further 31 per cent increase in incidence and a 21 per cent rise in deaths by 2030. More than one million under-50s now die from cancer each year, making the identification of causes a global health priority.
Early-onset breast, tracheal, bronchus and lung, stomach, and colorectal cancers accounted for the highest mortality and burden in 2019, while the incidence rates of nasopharyngeal and prostate cancers have shown the fastest increasing trend. The disease disproportionately affects the 40–49 age group, which is projected to represent a significant share of cases and deaths in the coming decade. Women under 50 carry a heavier cancer burden than men of the same age: in 2021 the incidence rate for young women was 82 per cent higher than for young men. Geographically, North America, Australasia and Western Europe have the highest rates, but low- to middle-income countries are also significantly affected, with high death rates recorded in Oceania, Eastern Europe and Central Asia. Established risk factors include dietary patterns high in red meat and sodium and low in fruit and milk, as well as alcohol consumption, tobacco use, obesity, physical inactivity and high body mass index.
Sleep Disruption Emerges as a Potential Factor
Two large studies led by the MD Anderson Cancer Center in Houston, Texas — one of the world’s leading cancer research organisations — have added a new dimension to the search for answers: poor sleep. The studies, presented at the American Society of Clinical Oncology’s annual meeting in Chicago, analysed health data from more than 18 million adults in the United States aged between 18 and 50. Researchers found that people with disrupted sleep patterns were more likely to develop early-onset bowel, breast, uterine or ovarian cancer. In some cases, under-50s diagnosed with insomnia were up to three times more likely to develop cancer within five years. For example, those with poor sleep had triple the risk of being diagnosed with breast cancer within five years of an insomnia diagnosis and were nearly twice as likely to develop uterine cancer.
The link between sleep disruption and cancer extends beyond insomnia. Obstructive sleep apnoea (OSA) has shown a particularly strong association with increased cancer risk, more aggressive cancers and higher mortality among cancer patients — believed to be due to reduced oxygen availability to cells during sleep. Night shift work, which disrupts natural circadian rhythms, has been linked to a higher risk of several cancers including breast, colorectal, gastrointestinal, skin and lung cancers. Women working long-term night shifts showed a 19 per cent higher overall risk of cancer, with specific risks even higher. The International Agency for Research on Cancer has classified shift work involving circadian rhythm disruption as a “possible human carcinogen”. Even sleep duration matters: both insufficient sleep (six hours or fewer) and prolonged sleep (nine hours or more) have been linked to increased cancer risk, though research results are mixed. Short sleep may raise risks for breast, colorectal, lung and prostate cancers, while long sleep may be associated with colorectal and lung cancer.
One possible mechanism is the immune system. Chronic sleep problems may weaken the body’s ability to detect and prevent cancer, whereas quality sleep strengthens immune defences. Researchers are also mindful of a “chicken or egg” problem: cancer itself, or its treatment, can disrupt sleep, and some evidence suggests sleep disturbances can be early symptoms of tumours. Despite these complexities, the MD Anderson team said: “These findings suggest that sleep disruption may represent a clinically relevant, potentially modifiable risk factor in early-onset cancer risk stratification and warrants further investigation.”
Expert Reactions and Practical Advice
Experts not involved in the studies welcomed the findings but stressed the need for caution. Dr David Garley, a GP and director of the Better Sleep Clinic in Bristol, said the impact of insomnia on health conditions including cancer was of “growing interest”, but emphasised that the studies had identified an association rather than proof that sleep disruption causes cancer. “There are possible causes from the physiology that arises from poor sleep, but also the fact that when sleep-deprived it’s difficult to live a healthy life – there is more drinking, more obesity, less exercise, more smoking etc – and these may be what causes any possible increased risk,” he said. He added that sleep plays a role in restoring the immune system, and that understanding of the role of infective agents in cancer development is advancing. “So if your immune system takes a bit of a hit, then I suppose it would make sense that your risk of some cancers may increase. But it also might be the other way around. It could be that if you have cancer, and it’s not yet clinically obvious, it could be causing some change in how you sleep.”
Claire Coughlan, clinical lead at Bowel Cancer UK, noted that bowel cancer remains more common in over-50s but that a growing body of evidence shows cases are increasing in younger people. In the UK, approximately one in 20 bowel cancer cases now occur in individuals under 50, and rates in this age group have risen by 22 per cent between the early 1990s and 2018. Symptoms in younger patients can be mistaken for benign conditions such as irritable bowel syndrome or haemorrhoids, leading to delayed diagnosis. “We don’t know exactly why this is yet, but researchers currently believe it may be due to genetics and lifestyle factors,” Coughlan said. “This study’s conclusion that insomnia may be a potential risk factor in early-onset colorectal cancer could go some way to helping us understand the reasons behind this increase. The findings of this study are worth exploring further.” Bowel Cancer UK’s “Never Too Young” campaign aims to raise awareness and improve diagnosis and care for younger patients.
Megan Winter, a health information manager at Cancer Research UK, said: “These studies explore whether there could be a link between insomnia and some types of cancer in people under 50, but more research is needed, particularly looking at people over longer periods of time, before we can draw any conclusions.” In the meantime, she added, people could reduce their cancer risk by not smoking, maintaining a healthy weight, and staying safe in the sun. Researchers are also investigating broader environmental factors — the “exposome” of diet, pollution, psychosocial stress and disruptions to the gut microbiome — and a possible “birth cohort effect” in which lifestyle changes since the mid-20th century have disproportionately affected recent generations. The MD Anderson studies, presented at the world’s largest cancer conference, underscore that sleep disruption is emerging as a clinically relevant, potentially modifiable target for understanding and possibly curbing the rise of early-onset cancer.