Adding @frongt@lemmy.zip's comment with some good context here:
each 50 gram portion of processed meat eaten daily increases the risk of colorectal cancer by 18%
And processed meat is defined as:
meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavour or improve preservation. Most processed meats contain pork or beef, but processed meats may also contain other red meats, poultry, offal, or meat by-products such as blood. Examples of processed meat include hot dogs (frankfurters), ham, sausages, corned beef, and biltong or beef jerky as well as canned meat and meat-based preparations and sauces.
And if you want a visual for 50g of processed meat: https://www.cbc.ca/news/canada/saskatoon/five-meats-by-the-slice-see-how-little-50-grams-actually-is-1.3289822
So that’s a reasonable amount for a regular meat-eating person to consume through meat dishes day to day.
I wonder how fast the risk changes with a change of diet. If I eat sandwiches and hot dogs one year and then veggies and beans the next does it drop to 0 in the second year?
No, you have a base risk from genetics and environmental factors. And a nonzero risk from those other foods. Processed meat is just 18% higher.