When “X-Men” actor Adan Canto died at just 42 from a tumor in his appendix, it cast a spotlight on a cancer so rare that many physicians have never encountered it.
His death in January 2024 drew attention to a troubling trend that researchers are only beginning to understand: Rates of appendiceal cancer are rising sharply among Gen X and millennials.
While the absolute numbers remain small—affecting roughly 3,000 Americans annually—this steep increase has prompted epidemiologists to track an emerging pattern that oncologists say they’re increasingly seeing in younger patients.
The Rising Risk
The appendix, a small, finger-like pouch attached to the large intestine, was once considered medically useless. However, some researchers believe it serves a role in gut health. On the flip side, it can also harbor several kinds of cancer.Researchers analyzed national cancer registry data from 1975 to 2019 and identified 4,858 cases of appendix cancer in adults aged 20 and older. They found a clear generational picture: People born around 1980 were more than three times as likely to be diagnosed with appendix cancer as those born in 1945, while those born around 1985 faced more than four times the risk.
Although still rare—affecting one to two people per million—the incidence of appendix cancer has risen steadily. Case rates increased by an average of 3.7 percent per year, higher than the typical 1 percent to 2 percent annual increase seen in most cancers.
The pattern held across all age groups, but older millennials are seeing the fastest rise, suggesting a “birth cohort effect”—a phenomenon in which people born around the same time may share long-term environmental or behavioral exposures that shape disease risk decades later.
Rates rose across all major types of appendix tumors, including mucinous, nonmucinous, and goblet cell adenocarcinomas. Goblet cell tumors, which occur almost exclusively in the appendix, were nearly five times more common in people born in 1980 than in those born in 1945. Mucinous and nonmucinous tumors more than doubled in the same time frame.
“It’s not just age, and it’s not just that we’re finding more because we’re looking harder,” Holowatyj said. “We don’t fully understand the causes yet—but that’s exactly why we need more research and awareness.”
There are no established screening tools or prevention guidelines for appendix cancer. Nearly half of all patients are diagnosed only after the cancer has already spread to other organs.
Holowatyj and others say it’s unlikely the rising numbers are due to better detection. Colonoscopies rarely detect tumors in the appendix, and imaging may miss them altogether—especially if the appendix isn’t clearly visible or the cancer presents in unusual ways.
Hidden and Hard to Diagnose
Appendix cancer symptoms often mimic common digestive problems, leading to delayed diagnosis. Holowatyj’s team surveyed 352 patients and found that 77 percent had symptoms before diagnosis, with more than half suffering for three months or longer.- Persistent abdominal pain
- Bloating
- Pelvic pain
- Abdominal masses.
“As a millennial myself, I say this to my peers: If something feels off, say something,” Holowatyj said. “It’s better to check and be wrong than to wait and be diagnosed late.”
With no clear diagnostic tools, most appendix tumors are discovered incidentally after an appendectomy—the surgical removal of the appendix, typically performed for appendicitis. Previously, appendix cancers were sometimes misclassified as colon cancers because of their close anatomical location. However, new research has shown these tumors are biologically distinct, the study noted.
Another complicating factor: Younger patients, who are now at the greatest risk, may also be less likely to have their appendix removed at all. A growing number of appendicitis cases are treated with antibiotics instead of surgery.
“Antibiotics won’t resolve tumor cells if they’re present,” Holowatyj said. “If a tumor is there, managing appendicitis nonsurgically may delay a diagnosis that’s already difficult to make.”
Taken together, the findings point to a broader shift in cancer patterns—one that may not be limited to the appendix but could reflect emerging risks to gastrointestinal health overall.
The trend mirrors increases in other early-onset gastrointestinal cancers, including colorectal and stomach cancers, which have also risen among younger adults. These trends may be linked to changes in diet, the microbiome, inflammation, early-life exposures, or yet-unidentified environmental factors.
What Comes Next
International collaborations, including the Appendiceal Cancer Consortium, are also underway to identify shared environmental and lifestyle risk factors—from early-life exposures to diet and inflammation—that might eventually help guide prevention.“This is still a rare disease,” Holowatyj said. “But the numbers are going up, and we need both providers and the public to have it on their radar—especially when symptoms persist.”
