Although they are very rare, cancers of the appendix are on the rise, a new study finds.
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 the report, published Monday in the Annals of Internal Medicine.
“There is a disproportionate burden of appendix cancer among young individuals,” said the study’s lead author, Andreana Holowatyj, an assistant professor of hematology and oncology at the Vanderbilt University Medical Center and Vanderbilt Ingram Cancer Center.
Holowatyj’s earlier research was “the first to show that 1 in every 3 appendix cancers is diagnosed among adults younger than age 50,” she said in a phone interview. “That’s compared to 1 in every 8 colorectal cancers diagnosed among adults younger than age 50.”
Still, appendix cancers are extremely rare: According to the National Cancer Institute, they occur at a rate of 1 to 2 per million people in the United States a year.
To see whether rates of the cancer had changed over time, Holowatyj turned to the Surveillance, Epidemiology and End Results program, which includes data from nationally representative cancer registries that cover about 45.9% of the U.S. population.
Overall, there were 4,858 cases of appendix cancer from 1975 through 2019.
When the large proportion of patients diagnosed between ages 18 and 49 is combined with the new finding of a generational rise in Gen X and millennials, it’s “important that we find the causes underpinning these statistics in order to reverse this trend and reduce the disease burden,” Holowatyj said.
The new study further confirms that there is a trend toward younger and younger patients from recent generations being hit with gastrointestinal cancers, said Dr. Andrea Cercek, a medical oncologist and a co-director of the Center for Early Onset Colorectal and GI Cancers at Memorial Sloan Kettering Cancer Center in New York City.
In particular, rates of colorectal cancer in younger adults have been rising for several decades. The cause for the rise in such GI cancers needs more research.
“It’s likely that there are environmental causes, which include exposures to food, water and micro plastics or lifestyle or dietary changes,” said Cercek, who wasn’t involved with the new research. “You can’t really pin it down to one thing or another. It’s likely multiple factors causing this rise after 1945.”
The appendix is a small pouch that hangs off the large intestine on the lower right side of the abdomen. A blockage can lead to infection and inflammation, called appendicitis, which needs emergency treatment.
Unlike other cancers of the GI tract, appendix cancers aren’t easily found because they’re not as easy to see on abdominal scans and won’t be picked up by colonoscopies, said Dr. Deborah Doroshow, an associate professor of medicine at the Tisch Cancer Institute at the Icahn School of Medicine at Mount Sinai in New York City. “So it’s not easy to detect or screen for them.”
In fact, Holowatyj said, about 95% of appendix cancers aren’t spotted until after a person has appendicitis and the appendix is removed and examined by pathologists. As a result, the cancers tend to be at a late stage with poorer long-term prognoses, she added.
Doroshow, who wasn’t involved with the new study, said it’s important for patients and their doctors to be more aware of subtle symptoms. Symptoms such as changes in energy level, a new persistent pain or unexplained weight loss in a young person shouldn’t be ignored, she said.
“If a person is feeling that something is not right it’s always best to get an opinion,” Doroshow said. “We’ve diagnosed young people with cancer whom other health care providers had not taken seriously because they were young.”
Women and people of color may find they need to advocate for themselves, she added.
Doroshow said people shouldn’t be worrying about every single abdominal pain. Rather, it’s persistent pain that would be a concern.