Appendix Cancer Rates Rising in Younger Adults: Birth Cohort Effects in Appendiceal Adenocarcinoma Incidence Across the United States

Andreana N. Holowatyj, PhD, MSCI, Mary K. Washington, MD, PhD, Richard M. Goldberg, MD, Caitlin C. Murphy, PhD, MPH

Annals of Internal Medicine

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This recent study partly funded by The ACPMP Research Foundation looked at appendiceal adenocarcinoma (AA) and found that it's becoming more common in the United States.

Researchers used National Cancer Institute data to compare appendix cancer rates across generations. They found that people born in the 1980s were three to four times more likely to be diagnosed with this cancer than those born in the 1940s.

This rise was seen across different types of appendix cancer. Although it's still a rare disease, the trend is concerning and not yet well understood. The study highlights the urgent need to better understand what might be causing these increases — such as environmental, lifestyle, or other risk factors — and to raise awareness among both doctors and the public.

Similar patterns are being seen in other digestive system cancers, which suggests there might be shared causes that deserve more attention.

In light of this evidence of younger adults being diagnosed, this study underscores the importance of early detection and early referral to specialized care.

A summary of the findings are provided below. Read the full article here.

Organs in the Peritoneal Cavity

Background

Appendiceal cancer is a rare type of cancer that spreads to the abdominal lining in some patients. Incidence rates of appendiceal adenocarcinoma (AA) are increasing across all age groups in the United States. Birth cohort patterns of AA can provide new, etiologic clues into increasing rates but have not been examined.

Who Participated

This was a retrospective cohort study of 4,858 persons aged 20 years or older when diagnosed with appendiceal adenocarcinoma (nonmucinous, mucinous, goblet cell, or signet ring cell carcinoma) between 1975 and 2019.

Key Findings

Rates of appendiceal adenocarcinoma more than tripled among patients born between 1976 and 1984 (1980 birth cohort) and quadrupled among those born between 1981 and 1989 (1985 birth cohort) compared with the 1945 birth cohort. Age-specific incidence rates of appendiceal adenocarcinoma increased across successive birth cohorts after 1945 — although to varying degrees — for all subtypes of appendix cancer.

Conclusion

There are strong yet distinct birth cohort implications for appendiceal adenocarcinoma that remain unexplained - particularly for young adult populations. Given these patterns, there is a timely need for research and increased awareness of appendix cancers 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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