Appendix Cancer Is Tripling in Millennials — And No One Knows Exactly Why

Most people have never given their appendix much thought. Fewer still have heard of appendiceal cancer. But new research suggests this rare disease is becoming far less rare among younger generations—and scientists are still trying to understand why.

Actor Adan Canto was 42 years old when he died of appendiceal cancer in January 2024. His diagnosis – made public only after his death – came as a shock partly because he was young, but also because so few people had ever heard of the disease that killed him. Appendiceal cancer, a rare cancer affecting young people with growing frequency, doesn’t come with the household name recognition of breast or colon cancer. It doesn’t have a ribbon. It doesn’t have a screening program. And according to new research out of Vanderbilt University, it’s quietly tripling and quadrupling in generations who were never supposed to be at risk.

The appendix is a small, finger-shaped pouch attached to the large intestine in the lower right abdomen. For most of medical history, it was treated as a biological footnote – an organ you only thought about when it became infected. Appendiceal cancer was rarer still, so infrequently diagnosed that most oncologists might see only a handful of cases in their careers. That picture is changing fast, and the shift is falling squarely on people in their 30s and 40s.

Researchers can describe the trend in precise detail. They can tell you which birth years are most affected, how survival rates split across racial groups, and how many people are likely to be diagnosed this year. What they cannot yet tell you is what’s driving it – or how to catch it before it becomes catastrophic.

A Rare Cancer Climbing Through the Generations

An analysis of a National Cancer Institute database found that compared with older generations, rates of appendix cancer have tripled among Gen X and quadrupled among millennials, according to a report published in the Annals of Internal Medicine. The lead researcher behind these findings, Andreana Holowatyj, an assistant professor of hematology and oncology at Vanderbilt University Medical Center, has been tracking this trend for years. She describes “a disproportionate burden of appendix cancer among young individuals,” pointing to earlier work she led that was “the first to show that 1 in every 3 appendix cancers is diagnosed among adults younger than age 50.”

Cases of appendiceal cancer tripled for Americans born between 1976 and 1984 and quadrupled for those born between 1981 and 1989, according to the study published in the Annals of Internal Medicine. Holowatyj’s earlier research, published in 2020 in the journal Gastroenterology, documented just how sharp that climb had already become, drawing on the National Cancer Institute’s own SEER database to confirm the scope of the generational shift. A separate government analysis found that overall malignant appendiceal cancer incidence increased 232% between 2000 and 2016 in the United States alone.

Cancer of the appendix is rare, affecting only about one or two people per million each year in the U.S. But rarity doesn’t equal safety, especially when the incidence trajectory keeps climbing. One subtype is climbing even faster. Research published in PLOS ONE found that appendiceal neuroendocrine tumors, a specific category of growths affecting hormone-producing cells in the appendix, saw their annual incidence rise from 0.03 to 0.90 per 100,000 person-years between 2000 and 2017 – a nearly 30-fold increase in under two decades.

Why Appendix Cancer Is So Hard to Catch

The appendix is a small pouch on the lower right side of the belly, connected to the large intestine, and appendix cancer often causes no symptoms until it ruptures – when signs can include abdominal or pelvic pain, bloating, nausea, and vomiting. Those symptoms overlap almost exactly with appendicitis. That overlap is part of what makes early detection so elusive.

Among modifiable risk factors for early-onset gastrointestinal cancers, dietary patterns have emerged as key contributors to broader increases. For appendiceal cancer specifically, the trail goes cold quickly. Little is known about why this is happening, and with no confirmed risk factors and no guidance on prevention, more research is needed to identify the factors driving this trend.

As Holowatyj has noted, “There are no standardized screening techniques for appendiceal cancers. Many of them are incidentally found after presentation of something like acute appendicitis.” According to Moffitt Cancer Center, no standardized appendix cancer screening tests reliably detect the disease, and colonoscopy isn’t a reliable solution because appendiceal tumors don’t typically invade the interior of the colon where a scope can find them.

When Chris Williams started feeling sharp stomach pain one night in 2021, he went straight to the emergency room. The next morning, he had surgery to remove his appendix. A few days later, doctors found a tumor on his appendix. Tests showed it was cancer – and it had already reached stage 3. “Had it stayed in me for a while longer, it would have been stage 4,” Williams told CNN. He was 48. His case, though fortunate in its accidental discovery, illustrates a broader pattern: about 95% of appendix cancers aren’t spotted until after a person has appendicitis and the appendix is removed and examined by pathologists.

As Holowatyj has explained, “This is a disease where, if not caught before the appendix ruptures, tumor cells disperse throughout the abdominal cavity often. That’s why up to 1 in every 2 patients are diagnosed with metastatic disease.” Metastatic means the cancer has spread beyond its point of origin – in this case, into the abdomen – which drastically limits treatment options and survival odds.

Vanderbilt researchers who published an action plan for appendiceal cancer have documented the survival consequences: five-year survival rates span between 10% and 63%, depending on cancer type and stage at diagnosis. That’s an extraordinarily wide range, reflecting how differently localized and metastatic cases behave. A patient whose tumor is caught before it spreads has a genuinely reasonable outlook. A patient diagnosed after abdominal dispersal faces some of the worst odds in oncology.

Treatment is further complicated by the biology of the disease. Research from the Holowatyj Lab at Vanderbilt has established that appendiceal tumors harbor different molecular features from colorectal cancers and respond differently to chemotherapy. That distinction matters enormously because, in the absence of appendix-specific clinical trials, oncologists have historically treated the disease using protocols designed for colon cancer. As Holowatyj has noted, the National Comprehensive Cancer Network guidelines recommend treating appendiceal cancer “as a right-sided colon tumor” – a practice driven by the absence of robust appendix-specific data, with treatment regimens extrapolated from colon cancer studies.

The Suspects: Diet, Environment, and Chemicals

Researchers don’t have a confirmed cause, but several suspects keep appearing in the literature. Holowatyj has noted that “we’re seeing some of these generational effects for cancers of the colon, the rectum, the stomach,” suggesting shared and distinct risk factors may contribute to cancer development across younger generations.

The broader picture of rare cancer in young people fits this pattern. A 2025 study published in ESMO Open found that global incidence of early-onset cancer rose by 79.1% between 1990 and 2019, with gastrointestinal cancers among the fastest-climbing types. The acceleration tracks closely with lifestyle changes that took hold in the 1980s and 1990s – the formative decades for Gen X and older millennials.

Environmental exposures are increasingly being examined. Experts suspect “environmental causes, which include exposures to food, water and microplastics or lifestyle or dietary changes” as likely contributors. Microplastics, forever chemicals such as PFOA and PFOS that contaminate drinking water, and the explosion of ultra-processed foods in the Western diet have all been implicated in rising gastrointestinal cancer rates among younger adults.

Rates of several cancers are rising in young adults beyond the gastrointestinal tract, including breast and myeloma. Interestingly, rates of atherosclerosis – hardening of the arteries – are also rising in younger adults, compared to decreasing rates in older people. That convergence points toward something systemic rather than organ-specific, though the precise mechanisms remain under investigation.

You can read more about how diet and lifestyle may be fueling gastrointestinal cancers in younger generations in this breakdown of rising colon cancer rates in young adults.

Who Is Most at Risk, and Who Bears the Greatest Burden

Appendiceal cancer doesn’t distribute its harm equally. A study by Andreana Holowatyj and colleagues – the first of its kind to examine appendiceal cancer patterns and survival by race and ethnicity among patients younger than 50 in the U.S. – found poorer disease outcomes among non-Hispanic Blacks compared with non-Hispanic whites. Among 1,652 cases of appendiceal cancer diagnosed in people aged 20 to 49 from 2000 to 2011, five-year cancer-specific survival was 77% for non-Hispanic whites, 64.5% for non-Hispanic Blacks, and 79.2% for Hispanics. The study, published in the journal Gastroenterology, found that socioeconomic status was similar for young non-Hispanic Blacks and Hispanics diagnosed with early-onset appendiceal cancer, suggesting that although socioeconomic factors may impact survival rates, they do not completely explain the survival gap between racial groups.

That gap in outcomes for non-Hispanic Black patients remains unexplained. In ongoing studies, the team aims to determine how health behaviors, environmental exposures, genetics, and gene-environment interactions contribute to differences in disease susceptibility and survival. Until those answers arrive, the disparity persists without a clinical remedy.

Appendix cancer, once considered extremely rare, is not so rare anymore – specifically among Generation X and millennials. Adan Canto’s death at 42 brought a moment of public attention to the disease. Decades earlier, Audrey Hepburn battled a rare appendiceal cancer called pseudomyxoma peritonei (PMP), which is in the same family of cancers as colon cancer – she died from it at age 63 in 1993. Today, doctors are seeing patients who are even younger.

What to Do Now

No blood test, no imaging protocol, and no routine scan currently exists that reliably catches appendiceal cancer before it spreads. Persistent abdominal pain, recurring bloating, and unexplained changes in bowel habits that don’t resolve on their own deserve a prompt conversation with a doctor rather than a wait-and-see approach. Experts say it’s important for patients and their doctors to be more aware of subtle symptoms – changes in energy level, a new persistent pain, or unexplained weight loss in a young person shouldn’t be ignored. These symptoms frequently get attributed to irritable bowel syndrome or dietary sensitivities in younger patients, and that misattribution is part of what delays diagnosis.

For anyone with a first-degree relative who has had appendiceal cancer, that family history is worth raising explicitly with a physician. Vanderbilt research has established inherited risk factors for appendiceal cancer, and while no formal screening protocol exists, a doctor who knows your family history may be more alert to early warning signs. When the large proportion of patients diagnosed between ages 18 and 49 is combined with the generational rise in Gen X and millennials, the trend “further confirms a trend toward younger and younger patients from recent generations being hit with gastrointestinal cancers,” according to Dr. Andrea Cercek, co-director of the Center for Early Onset Colorectal and GI Cancers at Memorial Sloan Kettering Cancer Center. Treating abdominal symptoms in your 30s and 40s as automatically benign is no longer medically sound. If a symptom is new, persistent, and unexplained, it’s worth investigating – not because alarm is warranted, but because catching this disease early is the single biggest factor in determining what happens next.

Disclaimer: This information is not intended to be a substitute for professional medical advice, diagnosis, or treatment and is for information only. Always seek the advice of your physician or another qualified health provider with any questions about your medical condition and/or current medication. Do not disregard professional medical advice or delay seeking advice or treatment because of something you have read here.

AI Disclaimer: This article was created with the assistance of AI tools and reviewed by a human editor.

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