The rising incidence of cancer in the young: What it means and why it is happening
The recent announcement that Her Royal Highness, Duchess of Cambridge Catherine “Kate” Middleton, who is destined to be Queen of England, is undergoing treatment for cancer was a shocking revelation to many. Middleton, 42, has three small children: George (10), Charlotte (8) and Louis (5). Her diagnosis was the latest blow to a British royal family rocked by the recent deaths of both Prince Phillip (2021) and Queen Elizabeth II (2022), scandalous revelations about Prince Andrew, bitter conflict between the future King William and his brother Prince Harry, and another recent diagnosis of an undisclosed type of cancer in King Charles.
Middleton’s diagnosis is an unfortunate reflection of a worldwide trend: The rising incidence of cancer in persons under the age of 50.
In the United States, this trend has been reflected primarily via a rising incidence of gastrointestinal (GI) malignancies. Actor Chadwick Boseman’s 2020 death at age 43 from metastatic colorectal cancer, the most common GI malignancy, was shocking to many. Still, Boseman’s diagnosis reflected a trend that the medical community has noted for well over a decade — and it extends to other GI cancers as well, with a rising incidence of cancers of the stomach, pancreas, esophagus, bile ducts and appendix, among others.
The global impact of cancer on human health is obvious. Cancer is the second-leading cause of death overall in the U.S. and the leading cause in persons under the age of 85. Since 2007, U.S. cancer rates have fallen for adults over 50. Cancer survival has also improved in that population, thanks to advances in both early detection and treatment.
Over the same time span, however, there has been a steady rise in the incidence of malignancies in the young. A 2023 study using the National Cancer Institute’s SEER database between 2010 and 2019 showed an overall increase in early-onset cancer (under age 50) of 0.74% during the study period, as compared to a 0.87% decrease in cancer incidence among individuals over 50. Gastrointestinal cancers had the greatest increase in the younger cohort, at 14.8%, followed by endocrine cancers (8.69%) and breast cancer (7.7%).
The most dramatic increases in cancer incidence occurred in persons between 30 and 40 years of age.
Similar findings are being seen worldwide. A British Medical Journal study looking at early-onset cancers (less than 50 years of age) throughout the world from 1990-2019 showed a shocking 79.1% increase since 1990. However, cancer mortality during that time only increased by 27.7%, primarily due to improved treatments (five-year survival rates for all cancers have increased from 49% in the 1970s to ~69% in 2019).
Once again, although early-onset breast cancer was the most common malignancy in this age range, the greatest increases were seen in the GI malignancies, a finding replicated in North America, Europe, Australia, and Asia. A recent study from Canada showed that individuals born after 1980 were 2 to 2.5 times more likely to be diagnosed with colon cancer than previous generations of the same age. A recent systematic review of early-onset colorectal cancer of 40 studies crossing 12 countries over five continents showed a worldwide 30% increase in early-onset colorectal cancer over the past 20 years. This sort of finding is what led the U.S. Preventive Health Services Task Force to recommend lowering the age for routine colorectal cancer screening to age 45 from 50 in 2021.
Like Kate Middleton’s experience, more of the early-onset cancer burden is being borne by young women rather than by men, partly based on the rising incidence of breast, endometrial and ovarian cancers in the female population, even though the lifetime probability of being diagnosed with invasive cancer is slightly higher for men (41.6%) than for women (39.6%).
Cancer is always an earth-shattering diagnosis to make. When a cancer diagnosis is made on someone who is young and in the prime of life, it is even more terrifying. My wife Daphne is an early-onset cancer survivor, having been diagnosed with lymphoma at age 28 and breast cancer at age 42. In my clinical practice, I commonly diagnose early-onset GI malignancies, including an otherwise healthy 32-year-old I found to have stomach cancer earlier this year.
So why is this happening?
Clearly, environmental concerns play a role. Diet is certainly a factor. The previously cited British Medical Journal article concludes, “Dietary risk factors (a diet high in red meat, low in fruits, high in sodium and low in milk, etc.), alcohol consumption and tobacco use are the main risk factors underlying early-onset cancers” ( ). A 2022 review article examining dietary influences on early cancer incidence implicated a Western-style diet (low in fiber, higher in fat, with more processed foods and sugars and more red meat) as a proinflammatory influence which may lead to an increased early cancer incidence. Chemicals present in our environment can also lead to cancer. Over 87,000 chemicals have been approved for use in humans, but less than 1,000 have been tested for carcinogenicity. Formaldehyde, perfluorinated chemicals (PFCs) used in nonstick surfaces, and certain components of polyvinyl chloride (PVC) have been shown to be carcinogenic — and this is just the tip of the chemical iceberg).
Other studies have linked drinking sugary drinks, obesity, and the ingestion of microplastics (abbreviated MPs) as possible causes. Most of these are felt to exert their effects through alterations in the gut microbiome, which has been recognized as having a profound and increasingly significant effect on individual human health. Gut dysbiosis is an alteration of gut microbiota in response to environmental or host-related changes associated with the manifestation, detection, or therapy of the disease.
It is increasingly appreciated that gut dysbiosis influences various conditions such as inflammatory bowel disease (IBD), neurodegenerative disease (e.g., Parkinson’s and Alzheimer’s), diabetes mellitus, autoimmune diseases such as lupus and rheumatoid arthritis, and cancer. Alterations in gut flora increase the risk of gastrointestinal malignancy by inducing chronic inflammation, producing mutagenic metabolites, modifying stem cell dynamics, and stimulating cell proliferation. Chronic inflammation by Helicobacter pylori has been associated with the genesis of both adenocarcinoma of the stomach and gastric lymphoma, and very specific alterations in gut microflora composition (i.e., increased numbers of oral cavity bacterial species such as Fusobacteria) have been associated with the development of colorectal cancer.
The idea of microplastics as a contributor to early-onset cancer is particularly intriguing. Plastic products have been used worldwide since the early 1900s but have been much more prevalent since ~1945. Plastics in the environment are broken down into microscopic particles (MPs), which are ingested by humans throughout their lifetimes, interacting with the lining of the digestive tract. It has been shown that MP ingestion can disrupt the GI tract’s protective mucus layer, particularly in the colon and rectum, influencing the composition of the protective gut microflora and potentially leading to enhanced exposure to carcinogens in the digestive system. The temporal correlation between the advent of microplastic exposure and the rise in early-onset cancer certainly raises concern, although no direct cause-and-effect relationship has been established.
The rising incidence of early-onset cancers is an unequivocal product of environmental influences. This is most likely the result of multiple disparate variables. The typical Western diet of ultra-processed foods with a relatively high animal fat content and a low proportion of fruits, vegetables, and whole grains plays a role. Ingested toxins and food additives, alterations in gut flora because of these and other influences, and the proliferation of ingested microplastics are also part of the equation. Scientists will need to focus research efforts on all these potential contributors as we try to mitigate cancer risk in generations to come.
This article originally appeared on Savannah Morning News: Mark Murphy: Why are more young people being diagnosed with cancers?
