Cancer of the appendix, the small pouch-like organ attached to the large intestine that supports the immune system, affects 1 or 2 people for every million people in the U.S., according to the research.
Archived version: https://archive.is/newest/https://www.independent.co.uk/news/health/appendix-cancer-gen-x-millennials-increase-b2770460.html
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Appendixes have been known medical problems for a long time. You can read books talking about it from the 1800s. One of the few things doctors could treat back then better than doing nothing (back before antibiodics and handwashing doctors were often worse than nothing)
there were many other things that could get you bacv then so overall apendix issues were not the most common causes of death.