Most commonly occurring cancers are diagnosed in people over age 50. Over the past several decades, however, rates of many types of cancer have been rising in adults under 50. Reports suggest that these include breast, colorectal, endometrial, esophageal, bile duct, gallbladder, head and neck, kidney, liver, pancreatic, prostate, stomach, and thyroid cancers as well as multiple myeloma.
Why are more people under 50 being diagnosed with cancer?
Some of the increase in earlier cancer diagnosis is occurring because more people are being screened for cancer at earlier ages, causing more cancers to be detected. Much of it, though, seems to reflect a genuine rise in the incidence of early-onset cancers — those diagnosed in people younger than 50.
Research studies suggest that, from an early age, more people are being exposed to factors that increase the chances of developing cancer while relatively young. These include changes in diet, lifestyle, rising obesity rates, environmental toxins, and shifts in the types of microorganisms in the digestive tract and elsewhere in the body. How these factors might affect different people, and how they might interact with those individuals’ genomes to raise cancer risk, however, is unclear.
In a recent paper in the journal Nature Reviews Clinical Oncology, researchers reviewed some of the trends potentially fueling the surge in early-onset cancers and the impact these trends are likely to have in the decades ahead. Among their findings:
- Per capita consumption of alcohol among people of any age increased from the 1960s to early 2010s in many countries. Research has established a link between alcohol use and the development of cancer, including liver, breast, and colorectal cancers.
- The global prevalence of obesity increased from 3.2% to 10.8% in men and from 6.4% to 14.9% in women from 1975 to 2014. In children and adolescents ages 5-19, it increased from 0.7% to 5.6% in girls and from 0.9% to 7.8% in boys from 1975 to 2016. Obesity has been linked to 13 types of cancer, including breast, esophageal, and endometrial cancers.
- While the prevalence of tobacco smoking has declined in many countries, it increased in successive generations of men in urban areas of China from the 1920s to 1950s and later. Tobacco smoke is the number one risk factor for lung cancer. Tobacco smoking among young people, which peaked in the 1990s and has been declining since, may be affecting current lung cancer rates. The effects of secondhand smoke in early life (from before birth to adolescence) remain uncertain.
- Diets that are high in saturated fats, red meat, sugar, and processed foods but low in fruits, vegetables, whole grains, and fiber have spread worldwide in all age groups over the past 50 years. Studies have found links between such diets and colorectal cancer.
- Physical activity has generally decreased among children and adolescents. Exercise can reduce the risk not only of developing cancer but having a recurrence following treatment.
“These observations suggest that changes in exposures, lifestyle, and screening are having an impact on the increasing rates of early-onset cancer,” says Timothy Rebbeck, PhD, of Dana-Farber and the Harvard T.H. Chan School of Public Health. “In response to these apparent trends, screening guidelines have changed to include younger populations. Younger individuals should follow these recommendations to reduce their risk of some cancers.”
Quick tips for lowering your cancer risk
The steps that young people can take to lower their cancer risk are the same as those for individuals of any age:
- Avoid tobacco in any form. The Centers for Disease Control and Prevention recommend the START method for quitting smoking or chewing tobacco.
- Stay physically fit and maintain a healthy weight for you. Experts recommend tailoring your fitness routine to your own abilities.
- Eat a healthy, balanced diet consisting of 50% fruits and vegetables, 25% lean proteins, and 25% whole grains.
- Avoid excessive sunlight exposure, particularly if you freckle or burn easily.
- Get vaccinated and practice safe sex to mitigate risk of infections that contribute to cancer, including hepatitis viruses, HIV, and the human papillomavirus (HPV). Get vaccinated against HPV and HBV (the hepatitis B virus). All these viruses can be transmitted by unprotected sex or needle sharing.
- If you drink alcohol, limit yourself to an average of one drink a day.