, according to a recent review.
While the rising incidence of early-onset colorectal cancer (CRC) is a well-documented problem, the trend appears to extend far beyond CRC. The authors traced patterns of early-onset cancer diagnoses across 14 different cancer types, including breast, prostate, and thyroid, over the past 3 decades and found increases in many countries.
Among the 14 cancers explored, eight relate to the digestive system, which highlights the potential role diet and the oral and gut microbiome may play in cancer risk, the authors noted.
And many of the factors that appear to influence cancer risk – such as diet, exercise, sleep, and vaccination against HPV and other cancer-causing microorganisms – are modifiable.
“[Our] immediate goals should be to raise awareness of the early-onset cancer epidemic and reduce exposure to [these] risk factors,” authors Tomotaka Ugai, MD, PhD, and Shuji Ogino, MD, PhD, with Harvard School of Public Health, Boston, noted in a joint email.
The paper was published in Nature Reviews Clinical Oncology.
While the rise in cancer screenings has contributed to earlier detection of cancers, a genuine increase in the incidence of some early-onset cancers also appears to be happening.
In the current review, Dr. Ugai, Dr. Ogino, and colleagues reviewed the literature and mapped trends in the incidence of 14 cancer types among 20- to 49-year-old adults in 44 countries between 2002 and 2012.
The authors found that, since the 1990s, the incidence of early-onset cancers in the breast, colorectum, endometrium, esophagus, extrahepatic bile duct, gallbladder, head/neck, kidney, liver, bone marrow, pancreas, prostate, stomach, and thyroid, has increased around the world. Looking at the United States, for instance, the average annual percent changes for kidney cancer was 3.6% in women and 4.1% in men and for multiple myeloma was 2% in women and 3% in men for 2002 to 2012.
This overall trend could reflect increased exposures to risk factors in early life and young adulthood, although “specific effects of individual exposures remain largely unknown,” the authors acknowledged.
Since the mid-20th century, substantial changes have occurred in diet, sleep, smoking, obesity, type 2 diabetes, and environmental exposures – all of which may influence the gut microbiome or interact with our genes to increase the incidence of early-onset cancers, the authors explained. For instance, obesity, smoking, and alcohol are all established risk factors for pancreatic cancer and have been linked with early-onset disease risk as well.
“Cancer is a multifactorial disease, and we are aware of the importance of genetics as a risk factor and screening for early detection, but this paper importantly brings to light the importance of correctable lifestyle habits that may slow the rise of early onset cancers,” oncologist Marleen Meyers, MD, director of the survivorship program at NYU Langone Perlmutter Cancer Center, who wasn’t involved in the review, said in an interview.
Although modifiable factors such as diet and exercise may ease the burden of these cancers, such changes are often difficult to implement, Dr. Meyers added. In addition, understanding the impact that certain factors, such as alcohol, obesity, physical activity, and delayed reproduction play in cancer risk requires more research to tease out, but “there is enough reason at this point to address these risk factors for both personal and public health benefits,” Dr. Meyers said.
Support for this research was provided in part by the U.S. National Institutes of Health, Cancer Research UK, Prevent Cancer Foundation, Japan Society for the Promotion of Science, and the Mishima Kaiun Memorial Foundation. Dr. Ugai, Dr. Ogino, and Dr. Meyers have disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.