The Statement "Meat causes cancer" is a bit of an overly simplified statement, that upon closer evaluation is correct on it's own, but there are other factors that seems to effect it such as smoking, lack of exercise, and how much fiber is in the diet. Like most topics to do with the human body, it's complicated. But plenty of research has been done to sufficiently make the link that eating processed meat increases the risk of cancer and tumors in the Colon.
WHO report says eating processed meat is carcinogenic
Source: Harvard School of Public Health
https://www.hsph.harvard.edu/nutritionsource/2015/11/03/report-says-eating-processed-meat-is-carcinogenic-understanding-the-findings/
" The World Health Organization has classified processed meats – including ham, salami, bacon and frankfurts – as a Group 1 carcinogen which means that there is strong evidence that processed meats cause cancer. Red meat, such as beef, lamb and pork has been classified as a ‘probable’ cause of cancer. These classifications do not indicate the risk of getting cancer, rather how certain we are that these things are likely to cause cancer."
Source: https://www.cancercouncil.com.au/cancer-prevention/diet-exercise/nutrition-and-diet/making-healthy-food-choices/meat-and-cancer/
There are several factors to how specifically eating meat can cause cancer and tumors, but it get a little more complicated than you need to get into.
If you really want to get into some of the details to how it causes cancer, you can watch this 8 minute video below by Mic the Vegan called: 5 Ways Meat CAUSES Cancer (w/ Science):
Our stomach acid and intestines are different from animals that evolved to eat meat. Carnivores and omnivores have short intestines, and herbivores and humans have long intestines. Plants don't cause colon and intestinal problems, so herbivores like Humans have a long small intestines to give more time to absorb nutrients, while carnivores like dogs have short intestines.
Ultimately my goal is to help people discover the many benefits of a plant based diet as I have. I don't miss meat and all the issues it brings to the Earth with it's atrocities and disease. In fact I enjoy a plant based diet much more than an animal product based one, as the food feels better in my stomach and the cooking experience is an art that includes awareness. Once you learn a few things it taste better than meat based meals. Plus it's much healthier and less likely to cause disease and sickness.
In conclusion there is enough scientific evidence that processed meat is classified as a group 1 carcinogen and red meat is a Group 2A. From all the research done on this you can conclude that Processed Meat is Directly Linked to Colo-rectal Cancer.
