Researchers have published a new study that takes a comprehensive look at the United States’ cancer rates. They aimed to measure and compare incidence rates of cancer diagnosis and mortality in different generations over time. The study concluded that the incidence rates of Gen X and Millennials were 2 to 3 times higher than those born in 1955. They are also more likely to develop 17 types of cancer. The researchers noted that the major contributing factors for this increase included environmental toxins, diet, and obesity. [1] However, more research is required to uncover the other factors involved in the rise in cancer rates. 

The Rise of Cancer Rates in Gen X and Millennials

The same researchers conducted a similar study in 2019, finding an increase in eight cancer types in more recent generations. However, until now, no study has taken both cancer incidence and mortality by birth year into account. The purpose of this new study was to bridge the huge gap in applicable data. [2] The researchers explained that exposure to carcinogenic factors early in life affected the incidence of cancer in those aged 50 or younger. [3] More people will develop cancer in the future as these young groups carry their increased risk into their senior years.

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The 17 Types of Cancer 

The study investigated the data of 23,654,000 individuals diagnosed with 34 different types of cancer. It also included data from 7,348,137 deaths from 25 cancers. The data from this sample group was from individuals who were diagnosed and died between 2000 and 2019. What they discovered was an increase in 17 of the 34 cancers in Gen X and Millennials:

• small intestine
• cardia gastric
• ovary
• estrogen receptor-positive breast
• non-HPV-associated oral and pharynx (in females)
• liver and intrahepatic bile duct (in females)
• Kaposi sarcoma (in males)
• anus (in males)
• colorectal cancer
• endometrial cancer
• gallbladder and other biliary
• pancreas
• kidney and renal pelvis
• myeloma
• non-cardia gastric
• Leukemia

Increase in Incidence and Mortality in Gen X and Millennials

The cancer incidence increase was especially pronounced in cancers of the pancreas, kidneys, renal pelvis, thyroid, and small intestine. Additionally, they noted that mortality rates increased in five types of cancer: liver, endometrial, gallbladder, testicular, and colorectal cancers. These findings are concerning because they show that the higher cancer risk in Gen X and Millennials isn’t just because we’re detecting and diagnosing cancer more regularly nowadays. Instead, it reveals a genuine and concerning rise in cancer risk at the population level. The number of new cases is growing so rapidly that it outweighs improvements in treatment.

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The Cause of the Increase of Cancer Incidence

The study aimed to collect new data on cancer incidence, yet it does not reveal the causes. However, the researchers are already aware of some of these factors. Obesity was one of the major factors noted, as it is associated with 10 of the 17 cancers the study had highlighted. The problem of obesity has generally increased in all age groups since the 1970s. However, the most rapid rise has been in individuals aged between 2 and 19 years. Other factors included environmental pollutants, altered sleep patterns, and a sedentary lifestyle.

Gut Microbiome and Dietary Factors

The increase in cancer incidence has also been linked to the modern diet favored in the West. [4] These foods are typically heavily processed and are high in sugar, saturated fats, and refined grains. Not only are heavily processed foods linked to weight gain, though. They have also been directly linked to an increased risk of developing colorectal and breast cancers. Since cancers that affect digestive systems are not linked to obesity, researchers believe gut microbiome changes could be a factor. They suggest that gut microbiomes are heavily impacted by both Western diets and the use of antibiotics. 

It’s Not All Bad News

Overall, the study showed a noticeable incidence increase of 17 cancers in Gen X and Millennials. However, it’s not all bad news, as the study also revealed that certain forms of cancer incidence are declining. Women born around 1990 are now less likely to develop cervical cancer. This is because HPV vaccinations were first approved in the U.S. when these girls were turning 16 years old. The drop in smoking rates has also resulted in a decline in esophagus, larynx, and lung cancers. While incidence rates overall have increased in Gen X and millennials, early detection has resulted in a mortality rate decline. 

The Bottom Line

Our understanding of cancer and its causes grows every day, along with advances in cancer treatment. However, many health issues we experience in our later years can result from factors that affect us in our youth. The study noted an increase in 17 types of cancer in Gen X and millennials, bringing to question the modern factors that afflict younger generations. Not all hope is lost, though. Despite this overall increase in cancer incidence, certain lifestyle changes have resulted in a decline in some cancers.