Higher risk of cancer among people under 50? Here's what study found out, potential causes

Over the past few decades, cancer has become more common in those under the age of 50. Researchers from Brigham and Women's Hospital found that early-onset malignancies, or those diagnosed before the age of 50, have significantly increased globally since 1990. These cancers include those of the breast, colon, oesophagus, kidney, liver, and pancreas.

In attempt to understand why so many younger people are being diagnosed with cancer, scientists conducted in-depth analyses of the readily available data in the literature and online, including information on early life exposures that may have contributed to this trend. The research's findings were published in Nature Reviews Clinical Oncology.

Professor and physician-scientist Shuji Ogino, MD, PhD, of the Brigham's Department of Pathology stated that researchers found from the data that the phenomenon is known as the birth cohort effect. This result indicates that people who were born later in time (by a decade or more) have a higher risk of developing cancer in later life, most likely as a result of risk factors they were exposed to when they were younger.

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"We discovered that the risk is growing with each passing generation. For instance, the chance of developing cancer before the age of 50 was higher for those born in 1960 than in 1950, and we expect that this risk will rise with time," Ogina further explained.

Tomotaka Ugai, MD, PhD, the study's senior author and an associate professor in the Department of Pathology, and his colleagues first examined global data on the incidence of 14 distinct cancer types in persons under the age of 50 between 2000 and 2012.

The team then looked for studies that focused at general population trends for potential risk factors, such as early life exposures. Finally, the team looked at the literature describing the differences between early-onset cancers diagnosed before the age of 50 and later-onset cancers in terms of clinical and biological tumour characteristics.

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The scientists conducted a thorough assessment and discovered that the early life exposome, which includes one's nutrition, lifestyle, weight, exposure to the environment, and microbiome, has altered significantly over the past few decades. They therefore put out the theory that the westernised food and lifestyle may be a factor in the rising rate of early-onset cancer.

The authors noted that early detection through cancer screening measures is partially to blame for this rise in the incidence of some cancer types. They were unable to quantify the exact percentage of this rising prevalence that could be simply due to screening and early identification. However, they pointed out that it is doubtful that an increase in the incidence of many of the 14 cancer types is the result of improved screening by itself.

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What are the potential causes?

Alcohol intake, sleep deprivation, smoking, obesity, and consuming highly processed foods were all potential risk factors for early-onset cancer. Surprisingly, researchers discovered that youngsters are getting far less sleep now than they did decades ago, despite the fact that adult sleep length hasn't changed significantly over the years.

Since the 1950s, risk factors have considerably increased, including highly processed meals, sugary drinks, obesity, type 2 diabetes, unhealthy lifestyles, and alcohol usage, which experts believe has been accompanied by changing microbiome.

Ugai explained  noted that among the 14 cancer types on the rise that we evaluated, eight were related to the digestive system. The microbes in our stomach are nourished by the food we eat. The microbiome's makeup is directly impacted by diet, and over time, these changes may have an impact on illness risk and prognosis.

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The lack of sufficient data from low- and middle-income nations to track trends in cancer incidence throughout the years is one of the study's limitations. Ogino and Ugai intend to carry on this research in the future by gathering more information and working with other international research institutions to better track global trends.

Additionally, they discussed the significance of undertaking long-term cohort studies with parental approval to include young children who may be monitored for decades. "Without such studies, it`s difficult to identify what someone having cancer now did decades ago or when one was a child," explained Ugai. 

(With inputs from ANI)