Appendix cancer cases are rising among Generation X and millennials — a trend that researchers say warrants increased awareness about the rare cancer.
A study published in the journal Annals of Internal Medicine found appendix cancer cases have tripled among people born between 1976 and 1984, and quadrupled for people born from 1981 to 1989, when compared to older generations. The study used data from appendix cancer diagnoses from 1941 to 1949 as a baseline.
The appendix is a finger-shaped pouch connected to the colon on the right side of the abdomen. It has long been believed to have little function, a leftover from when humans primarily eat leaves. It's best known for its potential to become inflamed and prompt emergency surgery, but it sometimes becomes cancerous.
Appendix cancer is still extremely rare — about 3,000 cases are diagnosed in the U.S. each year. By contrast, colorectal cancer — which also is rising among younger adults — results in 150,000 new cases each year. But 1 in 3 appendiceal cancer patients are diagnosed before age 50, whereas for colorectal cancer, that ratio is only 1 in 8.
The study's findings suggest medical professionals and the public need to give appendix cancer greater attention, researchers said. Recognizing symptoms such as abdominal pain, bloating, changes in bowel habits and the loss of appetite may lead to an early diagnosis, when cancer generally is more treatable.
Some appendix cancers are curable; the 5-year survival rate for low-grade appendix cancers ranges between 67% to 97%, according to the Cleveland Clinic. But appendix cancer lacks standardized screening guidelines, risk factors and tumor classifications, which contributes to nearly 1 in 2 appendix cancer patients being diagnosed after it has spread to distant organs, according to Vanderbilt University Medical Center, whose researchers led the study. In those cases, the five-year survival rate is 10% to 63%.
"Albiet cancer of the appendix is rare, it is important for individuals who have these symptoms to see a health care professional," lead study author Andreana Holowatyj, an assistant professor of medicine at Vanderbilt University Medical Center, said in a press release.
The study's research highlights the "birth cohort" effect — when a disease's incidence rate increases among successive generations, the New York Times reported. Dr. Andrea Cercek, a medical oncologist at Memorial Sloan Kettering Cancer Center in New York, who was not involved in the study, told the newspaper the effect supports the idea that increased exposure to certain risk factors make younger generations more susceptible than their predecessors.
Dr. Andrew T. Chan, a gastroenterologist at Massachusetts General Hospital, who was not involved in the study, told the Times that colorectal and gastric cancer may share some of the risk factors as appendix cancer, noting diet changes as a possibility. Consumption of ultraprocessed foods, including sugary beverages and processed meats, has risen over the years, has been linked to a higher risk of colon cancer.
Holowatyj said better diagnosis might play a role in the increased rates, too
The study concludes that "there are strong yet distinct birth cohort effects for (appendix cancer) across histologic subtypes that remain unexplained — particularly among persons born after 1945. Given these patterns, there is a timely need for etiologic research as well as increased (appendix cancer) awareness among providers and the public. Similar trends have been reported for other gastrointestinal cancers, suggestive of potential shared cause contributing to this increasing cancer burden across generations."
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